Pasquotank River Local Watershed Functional Rehabilitation Model Report

Transcription

1 Pasquotank River Local Watershed Functional Rehabilitation Model Report Prepared by Decision Support Professionals, Inc. For The North Carolina Wetlands Restoration Program December 2003

2 Pasquotank River Local Watershed Functional Rehabilitation Model Report Prepared by Decision Support Professionals, Inc. For The North Carolina Wetlands Restoration Program December 2003

3 Pasquotank River Local Watershed Functional Rehabilitation Model Report Table of Contents Executive Summary Introduction and Overview Objectives of the Functional Rehabilitation Model Development of the Functional Rehabilitation Model Functional Rehabilitation Model Framework Inventory and Description of Watershed Functions Creation of a Conceptual Model Site Selection NC-CREWS Functional Ranking Issue Identification Impact Identification Restoration and Rehabilitation Practices Functional Improvement Indicators Data Development Process Stakeholder Participation and Issues Identification Site Restoration and Rehabilitation Potential CommunityViz Background Introduction to the CommunityViz Software Framework CommunityViz Hardware and Software Requirements Data Requirements for Scenario Constructor Components of the Pasquotank River Local Watershed Functional Rehabilitation Model CommunityViz Scenario Constructor Framework Pasquotank River Scenario Framework Pasquotank River Scenario Indicators Pasquotank River Scenario Assumptions Pasquotank River Scenario Constraints Pasquotank River Scenario Auto Data References...24

4 Figure 1. Pasquotank River Local Watershed Functional Rehabilitation Model Management Plan Tables 1. Watershed Functions and Subfunctions Identified in NC-CREWS 2. Watershed Management and Screening Criteria 3. Effectiveness of Functional Restoration and Rehabilitation Practices for Control of Runoff In Wetlands and Riparian Areas 4. Estimating Percentage of Impervious Cover Appendix A. Pasquotank River Local Watershed Functional Rehabilitation Model - User Guide B. Pasquotank Watershed Issues/Potential Impacts and Restoration/Rehabilitation Practices C. Pasquotank River Local Watershed Functional Rehabilitation Model - Data Dictionary

5 PASQUOTANK RIVER LOCAL WATERSHED FUNCTIONAL REHABILITATION MODEL REPORT Executive Summary The Pasquotank River Local Watershed Functional Rehabilitation Model (Model) incorporates the data contained in the Revised Pasquotank River Local Watershed Characterization Report (PRLWCR), North Carolina Division of Coastal Management, NC Coastal Region Evaluation of Wetland Significance (NC-CREWS) model, Stakeholder Issue Book and Ranking Results, and other State and Federal data sources. The Model allows a user to; review the current state of and functions provided by the watershed, determine the potential impacts of landuse activities, and review alternative management strategies. In addition, the Model was designed to be used as a template for Watershed Functional Restoration Plans for other watersheds in the Coastal Plain. This report is accompanied by a disk that is a functioning model and can be used to screen, analyze, and identify specific project sites. The Model and the Pasquotank River Scenario, was developed in CommunityViz-Scenario Constructor module, a software program that is an extension to the ESRI ArcView platform. A complete list of hardware and software requirements can be found in Section 7.0 of this report. The User Guide and instructions for the Model and Pasquotank River Scenario can be found in Appendix A Introduction and Overview Watershed management can be an economical and environmentally sound way of improving water quality, preventing flood damage, protecting sensitive riparian and wetland ecosystems, enhancing habitat for fish and wildlife, and reducing impacts of landuse change over geographically large areas. Due to the size of a watershed like the Pasquotank River Local Watershed Planning Area and the many jurisdictional entities within it, meeting specific watershed improvement goals through a coordinated management effort is often difficult to achieve, particularly when downstream communities are affected by upstream activities. Wetland and riparian areas within a watershed provide water storage, aquifer recharge, wildlife habitat, forestry, and agricultural values. Sound farming, timber management, and construction practices can reduce runoff and nonpoint source pollution. A river fed by marshes, wet meadows, and riparian woodlands tends to flow steadily because of the gradual release of stormwater inputs, rather than the release of large quantity pulses all at once. These large quantity stormwater inputs can exacerbate degradation issues within areas where stormwater storage functions have been degraded or removed. Management practices in areas adjacent to a stream should seek to protect, enhance, restore, and rehabilitate those natural functions of stormwater retention, assimilation of nutrients and pesticides, and creation of food and cover for wildlife. Part of a watershed management plan should include recommendations to restore and rehabilitate areas that have been adversely affected by landuse activities and to provide guidelines for protection and enhancement of areas that continue to provide valuable ecological functions within a watershed. This report presents a model to identify, analyze, and refine potential restoration and/or

6 rehabilitation practices that will be the basis for and a part of the Pasquotank River Local Watershed Functional Restoration Plan. The Model is a systematic approach to the planning and decision making process that provides information, analysis tools, and expertise to the jurisdictions and stakeholders within the watershed. The Model considers the array of water quality, hydrological, and habitat functions that are provided by natural wetland and riparian areas and builds these functions into a set of recommendations that can be used by local decision makers, developers, and homeowners to avoid or minimize adverse effects of new development, agricultural and forestry practices, roadway and other infrastructure improvements. The Model was created in a GIS environment that allows the user to visualize, as well as measure, the effects of alternative management scenarios Objectives of the Functional Rehabilitation Model The role of the Functional Rehabilitation Model (Model) in watershed management focuses on three main objectives, which include (1) an overview of the basic functions provided by the natural wetland and riparian areas within a watershed, (2) a review of alternative restoration and rehabilitation practices that may be considered for the reduction or mitigation of potentially adverse effects of landuse activities in the watershed, and (3) development of a GIS-based model that provides a visualization of different management strategies to restore or rehabilitate sites at various locations in the watershed or subcatchments. The initial objective was to develop a systematic approach to characterize and assess the role wetlands and riparian areas play in maintaining watershed functions. Restoration of the functions of these wetlands, streams, and riparian resources would then play a critical role in the mitigation of adverse effects of urban development, agricultural practices, logging, construction of infrastructure, and other issues identified in a stakeholder process. Understanding wetland and riparian area functions would therefore lead to a greater degree of success in applying restoration and rehabilitation practices, including locating sites for wetland, stream, and riparian area restoration, enhancement, creation, and preservation within the watershed. These practices, along with others, will restore and rehabilitate the functions of the watershed: water quality, hydrology, and habitat. Streams are identified by the Model from data layers produced by the United States Geological Survey (USGS) as blue line or perennial streams. Segments of these streams can be analyzed to determine if alterations such as channelization have occurred by observations of long straight lines on the maps. However, many of the streams within the Pasquotank River Local Watershed Planning Area are swamp water streams and may not appear on the USGS maps. Further compounding the difficulty of analyzing these streams is the lack of watershed functional standards for swamp water streams. Monitoring data to determine stream conditions is difficult to obtain because of gradual slope and structure unique to braided streams and frequent reversing flows. The Model addresses these issues by identifying channelized streams where possible and relies on refinement of the data from field visual assessments. In order to understand the condition of watershed functions within the study region, the watershed and associated subcatchments would need to be characterized by functions they currently provide and by functions that would need to be restored and/or rehabilitated on a project-by-project basis. Watershed functions would also need to be identified and assessed at various watershed scales for individual subcatchments and the watershed. Functions should also have a spatial component so that they can be quantified; incorporated in empirical models, simulations, and visualization tools such as geographical information systems (GIS); and meaningful at an individual project site. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 2

7 Therefore, the goal of the Model was to identify and assess watershed and subcatchment functions and provide multiple strategies to address the threats to those functions. The development of the Model from the perspective of replacing watershed functions is important for watershed rehabilitation because wetland, stream and riparian restoration and rehabilitation projects alone cannot provide the level of functional improvement needed within a watershed. The strategies identified in the Model include not only wetlands, stream and riparian buffer restoration/rehabilitation projects, but also strategies that may be initiated through collaboration with other local, State and Federal programs, as well as private sector initiatives, to enhance the success of any single strategy. The second objective included an evaluation and comparison of alternative restoration and rehabilitation practices based on an analysis of all factors contributing to a naturally functioning watershed. This analysis was aided by the North Carolina Coastal Region Evaluation of Wetland Significance (NC-CREWS) 1 functional assessment model. The selection of NC-CREWS was based on a quantitative and qualitative approach to measuring and assessing the level of water quality, hydrologic, and wildlife habitat functions of wetlands and riparian areas. NC-CREWS was also created in a GIS environment, which enabled functions to be located and measured both spatially and visually. While NC-CREWS provided a set of criteria to assess wetland functions, assumptions were also made and incorporated into the Model regarding streams, riparian, and habitat areas in close proximity to identified wetland areas and the watershed functions that they provide. Restoration/rehabilitation of watershed functions is also dependent on local landuse policies and practices. In addition to using NC-CREWS data, the Model uses input provided by local stakeholders. Stakeholders will have the ultimate responsibility for local landuse decisions that could affect both the individual project sites, as well as the entire watershed. Addressing the issues expressed by these individuals and organizations played an important role in the development of the Model. The use of NC-CREWS and commercially available geographical information system (GIS) technologies, along with stakeholder input, enhanced the fulfillment of the third objective: the development of a Watershed Functional Rehabilitation Model using a GIS-based planning and decision support toolset called CommunityViz. Section 7.0 outlines the capabilities of CommunityViz and how it was utilized for determining potential restoration/rehabilitation practices to restore, enhance, and/or create watershed functions within the planning area Development of the Functional Rehabilitation Model The goal of the Functional Rehabilitation Model was to create a toolset that compiles and analyzes information about the Pasquotank River Local Watershed Planning Area and its individual subcatchments in order to meet restoration and rehabilitation objectives that will result in measurable improvements in water quality, hydrology, and habitat values. The use of a modeling approach and the selection of an appropriate decision support toolset provides both quantitative and visual analyses of existing and potential changes in watershed function. The 1 North Carolina Department of Environment and Natural Resources, North Carolina Coastal Region Evaluation of Wetland Significance (NC-CREWS), Strategic Plan for Improving Coastal Management in North Carolina. Division of Coastal Management. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 3

8 Model is designed to support nonpoint and point source water quality, hydrological, and ecological (habitat quality) investigations, assess present watershed conditions relative to locally identified issues, and simulate responses of wetlands and riparian areas within the watershed to various measures that could restore and/or rehabilitate natural functions. The focus of the Model is on the natural ability of wetlands and riparian areas to interrupt overland stormwater flows and protect streams by acting as filters for sediment and nutrient (nitrogen and phosphorus compounds) pollution that could lead to eutrophication of surface waters. For the purpose of this plan, wetlands are defined by the U.S. Environmental Protection Agency 2 as: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. Riparian areas are defined as: Vegetated ecosystems along a waterbody through which energy, materials, and water pass. Riparian areas characteristically have a high water table and are subject to periodic flooding and influence from the adjacent waterbody. These systems encompass wetlands, uplands, or some combination of these two land forms. They will not in all cases have all of the characteristics necessary for them to be classified as wetlands. The Restoration and Rehabilitation (R&R) practices incorporated in the Model were derived from best management practices (BMPs) developed by the U.S. Environmental Protection Agency (EPA) for wetland and riparian systems and from guidance derived from the study, Neuse River Basin: Model Stormwater Program for Nitrogen Control, for total nitrogen removal (NC Division of Water Quality, 1999). The Model does not consider BMPs created for non-wetland/riparian areas, nor does it consider such practices as source reduction, application of runoff control practices that account for daily or seasonal variations or fluctuations, preservation, or education. These options are considered during the site assessment process based on information provided by the Model and derived from stakeholder identified goals and management strategies in the Revised PRLWCR. 3.0 Functional Rehabilitation Model Framework Natural wetland functions, as defined by the North Carolina Division of Coastal Management (NCDCM), focus on the ability of a wetland to remove nonpoint source pollution from runoff and protect and improve the quality of surface water bodies. An assessment of how an individual wetland or riparian area provides these functions is, in turn, based on the fundamental principles of wetland ecology. According to Mitsch and Gosselink (1986), wetlands are valuable as sources, sinks, and transformers of a multitude of chemical, biological, and genetic materials. A naturally functioning wetland helps to cleanse polluted waters, prevent floods, protect shorelines, and recharge groundwater aquifers. Wetlands also play major roles in the landscape by providing unique habitats for a wide variety of flora and fauna. 2 Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters ( Accessed in Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 4

9 The Model uses the functional assessment procedure outlined in the North Carolina Coastal Region Evaluation of Wetland Significance (NC-CREWS) functional assessment model. NC- CREWS was developed for the coastal region and includes the types of wetlands and watershed habitats encountered in the Pasquotank River Local Watershed Planning Area. The NC-CREWS model rates wetlands and riparian areas by four main functions: water quality, hydrology, wildlife habitat and risk to watershed integrity if wetlands are lost. These functions were transformed from hard data into spatial data to allow for data manipulation and visualization using GIS. By combining an evaluation of the entire set of wetland functions measured using NC- CREWS criteria, the assumption that wetland functions can also be associated with stream and riparian areas, and input provided by local stakeholders, a better overall description of watershed functions could be developed. The process of converting NC-CREWS guidelines into the Functional Rehabilitation Model consisted of three component steps: 1. Inventory and description of watershed functions based on NC-CREWS. 2. Development of a conceptual model, which outlines the design used for the Model and Pasquotank River Scenario. 3. Creation of a Watershed Functional Rehabilitation Model and Pasquotank River Scenario in CommunityViz. Each of these components is described in the following sections of this report. 3.1 Inventory and Description of Watershed Functions There are six steps which create the Functional Rehabilitation Model. In step 1, a matrix (see Table 1 at the end of this report) was created for each of the functions and subfunctions identified in NC-CREWS: water quality, hydrological, habitat, and risk of loss. The table was created in MS Excel so that parameters (i.e., data and information resources used in an empirical model) outlined in the matrix could be automated in CommunityViz using GIS data entry protocols. Table 1 referenced at the end of the document, includes a number of other factors used in the Functional Rehabilitation Model that are used in developing and building the CommunityViz application. These factors (which correspond to terminology used in CommunityViz) include: Objectives. An objective indicates a desired outcome of restoration and/or rehabilitation of a watershed function (for example, removing accumulated sediment in a wetland to enhance its value for runoff interruption or flood retention). Indicators. The matrix includes a set of indicators of change for each of the individual functions and subfunctions. For example, an indicator of runoff might be proximity to source. Attributes. These are guidelines or metrics identified in NC-CREWS that give instruction to the user regarding how individual functions and subfunctions would be measured to determine the level of function present or needing to be restored and/or rehabilitated. Constraints. Constraints are factors (physical, chemical, biological, social, economic, regulatory, etc.) that must be considered when evaluating resources to be managed or for management actions. Constraints also serve as alerts to particular aspects of an area that has low functions according to NC-CREWS. These alerts display the functions that could Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 5

10 be improved by a potential project. Explanations. These are used to provide descriptive information, references to scientific studies or regulatory requirements, to interpret the conditions and values of individual subfunctions performed by a watershed under study, along with contextual information to interpret procedures used to assess Restoration and Rehabilitation (R&R) practices. The first column (in Table 1) provides an explanation of functions and subfunctions provided by watershed areas. The second column provides an explanation of various constraints associated with proposed restoration or rehabilitation measures. Data Requirements. Data that needed to be collected in order for the Functional Rehabilitation Model to characterize indicators, attributes, or constraints; calculate and measure change; and evaluate how close objectives are being met. The Model is used to create a representation of a functional assessment of an individual study area by converting data described in the PRLWCR into variables used in making these calculations. 3.2 Creation of a Conceptual Model The second step in the development of a Functional Rehabilitation Model is the creation of a conceptual model, which is shown in Figure 1. In systems theory, a conceptual model is a model of a model. A conceptual model starts with a systems diagram that provides a visualization of the components of any mathematical or empirical model and the interconnections among various parts of the model. The linkages/interconnections represent inputs for mathematical processes that occur within each component. The conceptual model of the Functional Rehabilitation Model is used to map out the functions of the actual model, so that there is a direct link between project requirements (objectives, assumptions, metrics, and data) and the parts of a Pasquotank River Scenario created using the CommunityViz-Scenario Constructor application that receives data from the GIS interface, measures changes based on user inputs, and displays results in a visual form. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 6

11 The conceptual model shown in Figure 1 was created as a flow diagram that describes six component parts of the Model that assesses wetland and watershed functions, assesses impacts of landuse changes in the watershed, and offers measures or management practices to restore or rehabilitate functions. The conceptual model also uses NC-CREWS for its underlying set of assumptions. The component parts of the conceptual model include: 1. Selection of potential project sites for restoration or rehabilitation using a weighted screening process. 2. Ranking of watershed functional values or performance regarding water quality, hydrology, or habitat as defined by NC-CREWS. 3. Identification of watershed issues, concerns, or problems within a specific subcatchment. 4. Evaluation of primary impacts related to selected watershed issues. 5. Development of restoration/rehabilitation practices or ecosystem management practices to mitigate impacts. 6. Predictions of potential results from restoration/rehabilitation practices and an evaluation of indicators of functional improvements to the watershed if such measures are taken. Each of these conceptual model components is described in greater detail below Site Selection The first component of the conceptual model depicted in Figure 1 is a characterization of functions provided within the watershed at existing locations. This information can also be used Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 7

12 as a first step in the Functional Rehabilitation Model as an initial screening process to identify areas that are presently providing watershed functions within the Pasquotank River planning area. The conceptual model identifies areas within the watershed in their present state that provide High, Moderate, and Low functionality. The characterization of High, Moderate, or Low functionality is based on measuring criteria and attributes used in NC-CREWS (e.g., distance to streams, proximity to floodplains or agricultural lands, soil types, and so on) using geospatial databases for the watershed converted to GIS thematic layers and ranked proportionally to obtain an overall ranking. These criteria were identified in Table 1 at the end of this report. NC-CREWS identifies 39 individual criteria that have a geospatial component, and each of these is systematically evaluated in the conceptual model. The logic followed by the conceptual model is that higher-value watershed areas are relatively undisturbed and thus provide the most functions (e.g., reduction of nutrients, stormwater retention, wildlife habitat) and would require relatively fewer restoration/rehabilitation practices. Project areas with moderate functional values could either be enhanced or restored depending on the level of disturbance and functions that would require more intensive restoration/rehabilitation practices. Project areas providing low functional value would require significant restoration/rehabilitation practices up to and including replacement or creation if there were no watershed functions present. The scale of the analysis uses a grid cell size of 400 X 400 meters (this grid scale can be varied depending upon whether the entire watershed, individual subcatchments, or site-specific projects are being evaluated). Areas within each grid cell were then ranked according to High, Moderate, and Low functionality and weighted using a proportional scale as depicted in Table 2. An area with High functionality was given a 0.6 weight; Moderate was given a 0.3 weight, and Low was given a 0.1 weight. While the scale is relatively coarse, the resultant GIS data layer is extremely graphic in its depiction of areas that are heavily influenced by local landuse practices. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 8

13 Table 2: Watershed Management and Screening Criteria Wetland Functional Category Indicator Metrics Weighting/ Theme Layer Ranking I. Water Quality Functions Runoff - Source > 20% perimeter agriculture and developed 0.60 Land use/cover Non-Point Source Pollution > 20% perimeter agriculture, developed, pine plantation 0.30 </= 20% perimeter agriculture, developed, pine plantation 0.10 Runoff Proximity to Water W/in 300 ft. of permanent surface water 0.60 Surface water Body W/in 300 ft. of intermittent surface water 0.30 > 300 ft. of permanent/intermittent surface water 0.10 Runoff Watershed Position Intermittent, first-order stream 0.60 Stream hydrography Second or third-order stream 0.30 Higher than third-order stream 0.10 Runoff Wetland Type Bottomland hardwood, swamp forest, headwater swamp 0.60 DCM wetlands Freshwater marsh, pine flat, hardwood flat, pocosin, maritime forest 0.30 Pine plantation, altered sites 0.10 Runoff - Soils Histosol or freq. flooded mineral soil w/ high clay or mineral content 0.60 NRCS soils I. Water Quality Functions Floodwater Cleansing Infrequently flooded mineral soil w/ high clay or organic matter 0.30 Infrequently flooded mineral soil w/ low clay or organic matter 0.10 Flooding Water Source > 20% of stream length in HU bordered by ag. or developed land 0.60 Land use/cover 5-20% of stream length in HU bordered by ag. or developed land 0.30 < 20% of stream length in HU bordered by ag. or developed land 0.10 Flooding Duration of Flooding Wetland is flooded long to very long periods 0.60 Floodplain Wetland is flooded brief periods 0.30 Wetland is flooded very brief periods or not at all 0.10 Flooding Wetland Type Bottomland hardwood, swamp forest 0.60 DCM wetlands Other wetland types 0.10 Flooding Soils Histosol or freq. flooded mineral soil w/ high clay or mineral content 0.60 NRCS Soils Infrequently flooded mineral soil w/ high clay or organic matter 0.30 Infrequently flooded mineral soil w/ low clay or organic matter 0.10 Flooding Width > 100 ft Floodplain ft II. Hydrology Functions Surface Runoff Storage < 50 ft Runoff Watershed Position Intermittent, first-order stream 0.60 Hydrography Second or third-order stream 0.30 Higher than third-order stream 0.10 Runoff Wetland Size Wetland > 0.54% of total HU area 0.60 Hydrography Wetland % of total HU area 0.30 Wetland < 0.05% of total HU area 0.10 Runoff Wetland Type Bottomland hardwood, swamp forest, headwater swamp 0.60 DCM Wetlands Freshwater marsh, pine flat, hardwood flat, pocosin, maritime forest 0.30 Pine plantation, altered sites 0.10 Runoff Soil Infiltration Soil hydrologic group A, B, or A/D 0.60 NRCS Soils Soil hydrologic group C or B/D 0.30 Soil hydrologic group D 0.10 II. Hydrology Functions Floodwater Storage Flooding - Duration Wetland is flooded long to very long periods 0.60 Hydrography Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 9

14 Wetland is flooded brief periods 0.30 Wetland is flooded very brief periods or not at all 0.10 Flooding Wetland Size Wetland > 0.54% of total HU area 0.60 Land use/cover Wetland % of total HU area 0.30 Wetland < 0.05% of total HU area 0.10 Flooding Watershed Position Higher than third-order stream 0.60 Hydrography Second or third-order stream 0.30 Intermittent, first-order stream 0.10 Flooding - Width > 100 ft Floodplain ft < 50 ft II. Hydrology Functions Shoreline Stabilization Erosion Proximity to Water Body < 50 ft. from shoreline of second or higher order stream or of estuary or 0.60 Surface water lake shoreline < 50 ft. from shoreline of first order stream or ft. from estuary 0.30 shoreline >/= 50 ft. from any stream or lake or >300 ft. from estuary shoreline 0.10 Erosion - Exposure > 500 ft. of wetland perimeter borders open water 0.60 Surface water ft. of wetland perimeter borders open water 0.30 < 100 ft. of wetland perimeter borders open water 0.10 Erosion Land Use >/= 1% developed or >20% developed + agriculture 0.60 Land use/cover < 1% developed or <20% developed + agriculture 0.10 III. Habitat Functions Endangered Species/Significant Natural Areas III. Habitat Functions Terrestrial Wildlife Habitat Occurrence 1.00 TBD (Internal) Habitat Size > 74 acres 0.60 Land use/cover 0-74 acres 0.30 No interior habitat 0.10 (Internal) Habitat Surface Water Adjacent to permanent surface water 0.60 Land use/cover Adjacent to intermittent stream 0.30 Not adjacent to surface water 0.10 (Internal) Habitat - Heterogeneity > 8 vegetative types within complex 0.60 Land use/cover 5-8 vegetative types within complex 0.30 > 5 vegetative types within complex 0.10 (Internal) Habitat Wetland Type Bottomland hardwood, freshwater marsh, hardwood flat, swamp forest 0.60 DCM Wetlands Headwater swamp, pine flat, pocosin, maritime forest 0.30 Pine plantation, altered sites 0.10 (Internal) Habitat landscape > 50% bordered by other wetlands 0.60 Land use/cover < 50% bordered by other wetlands 0.30 Isolated from other wetlands 0.10 (Internal) Habitat Surrounding > 50% land cover w/in 1/2 mile natural vegetation 0.60 Land use/cover > 50% land cover w/in 1/2 mile buffer combination of natural vegetation, 0.30 pine plantations, agriculture > 20% land cover w/in 1/2 mile developed or < 10% natural vegetation 0.10 Movement Corridors Corridor > 600 ft. wide connected to contiguous natural vegetation 0.60 Land use/cover Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 10

15 Corridor < 600 ft. wide connected to contiguous natural vegetation 0.30 Isolated from other natural vegetation 0.10 Island Isolated wetland > 5 acres w/in 1/2 mile of same 0.60 Land use/cover Isolated wetland < 5 acres w/in 1/2 mile of same 0.30 Wetland < 1 acre or > 1/2 mile of nearest wetland 0.10 III. Habitat Functions Aquatic Life Habitat Habitat Anadromous Fish Adjacent to river or tributary harboring anadromous fish; annual flooding; 0.60 TBD not channelized Adjacent to river or tributary harboring anadromous fish; stream 0.30 channelized Not adjacent to river or tributary harboring anadromous fish 0.10 Habitat Other Fish Species Adjacent to > third order stream w/ annual flooding 0.60 Hydrography Adjacent to first to third order stream w/ annual flooding or channelized 0.30 stream > third order Not adjacent to stream or stream has infrequent or nonexistent flooding 0.10 Habitat Wetland Type Bottomland hardwood, freshwater marsh, headwater swamp, swamp forest 0.60 DCM Wetlands Hardwood flat, pocosin, maritime forest 0.30 Pine plantation, pine flat, altered sites 0.10 Habitat Surrounding > 50% land cover w/in 1/2 mile natural vegetation 0.60 Land use/cover > 50% land cover w/in 1/2 mile buffer combination of natural vegetation, 0.30 pine plantations, agriculture > 20% land cover w/in 1/2 mile developed or < 10% natural vegetation NC-CREWS Functional Ranking The second component of the conceptual model provides a functional ranking of an individual site, which could include a single wetland, a wetland complex, a riparian area, an area containing mixed landuse, and so on. The conceptual model will also rank areas that were former wetlands converted to other uses. The conceptual model must be able to allow the user to locate study areas through the GIS user interface. A number of different restoration/rehabilitation scenarios might be considered based on the cumulative scores derived from the 39 NC-CREWS functional criteria. This component of the Functional Rehabilitation Model uses the Wetland Analysis Protocol 3 to determine the thresholds for different management strategies. An example of a management threshold might be a percent reduction of a nutrient or treatment of a specific number of acres. The second component of the conceptual model is also used to identify specific functions by project site that would need to be restored or rehabilitated. Essentially, this component is a GIS version of the NC-CREWS functional assessment protocol. As shown in Table 1, NC-CREWS is used in the conceptual model to provide a detailed description of any degraded or missing functions and provide the user with an overview of likely management options. In the conceptual model, this analysis is done automatically and provided to the user as a descriptive text message. 3 North Carolina Division of Coastal Management, Wetland Analysis Protocol for Restoration and Enhancement. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 11

16 3.2.3 Issue Identification The third component of the conceptual model provides the ability to (1) identify issues or concerns regarding ongoing or proposed landuse actions that could potentially affect a watershed, and (2) select issues that are pertinent to a specific subcatchment or project site. Issues can be identified through an assessment of potential impacts from an ongoing or proposed landuse activity, public policies, regulations, engineering design specifications, or stakeholder input. In the case of the conceptual model, issues have been identified through stakeholder participation. A list of these issues is shown in Appendix M of the Revised PRLWCR. The issue identification process resulted in a ranking of local concerns by subcatchment and by watershed Impact Identification The fourth component of the conceptual model provides a unique list of primary impacts that potentially result from the stakeholder issues (e.g., runoff, flooding, erosion, sedimentation, introduction of nutrients, loss of habitat, and so on). As shown in Figure 1, the majority of issues are relatively generic, such as residential development, streambed stability, logging practices, or invasive species. Other issues are more specific such as drop inlets or heat pump drainage. In most cases, however, identified issues are primarily the result of nonpoint-source pollution (increases in sediment and nutrients), hydrologic changes like flood retention, or eutrophication or loss of habitat. Identified issues can be broken down into primary impacts (e.g., direct introduction of sediment to a water body during construction of a project) and secondary impacts (e.g., cumulative impacts from all construction activities within a subcatchment). This process is shown in Appendix B of this report. A conceptual combination of components two, three, and four is basically an impact assessment process that describes how the conceptual model is able to assess a potential restoration site by functions to rehabilitate to address identified issues within the watershed and subcatchments. This process allows users of the conceptual model to see how potential impacts from nonpoint source pollution and other changes occurring in the watershed can be mitigated using a variety of restoration/rehabilitation practices at specific project sites Restoration and Rehabilitation Practices The fifth component in the conceptual model describes how restoration and/or rehabilitation practices are integrated into the conceptual model. The conceptual model simulates a typical decision process made after evaluation of a site in the field, but provides the project manager with a series of alternative restoration/rehabilitation practices. Appendix B shows how the conceptual model makes the assumption that restoration and/or rehabilitation practices could be based on best management practices (BMPs) for nonpoint-source pollution. The list of BMPs (Appendix B, column 4) was derived from the U.S. Environmental Protection Agency s Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters ( The conceptual model also used specific guidance derived from the study, Neuse River Basin: Model Stormwater Program for Nitrogen Control, for total nitrogen removal (NC Division of Water Quality, 1999). Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 12

17 The following assumptions were made: Wet detention ponds 25% removal Constructed wetlands 40% removal Riparian buffers 30% removal Vegetated filter strips 20% reduction The Neuse River guidelines indicate that the removal rate of more than one BMP installed in series should be determined through serial rather than additive calculations. Serial calculations take into account that the amount of reduction from implementing more than one BMP or restoration/rehabilitation practice will not equal the addition of the above removal efficiencies, but will represent a more realistic removal rate. In other words, a 25% removal rate for nitrogen of a wet detention pond means that 75% would not be removed. If the wet detention pond discharged into a constructed wetland, 40% of the remaining nitrogen would be removed. Thus, expected cumulative rate of removal of the two methods [25% + (75% x.4)] would be approximately 55%. This assumption was used in the Model. This evaluation led to a subset of restoration/rehabilitation practices for wetland and riparian projects as appropriate for the project area, particularly those that were developed for North Carolina coastal conditions. After a literature review, a final list of applicable restoration/rehabilitation practices (R&R practices) was developed and tested in CommunityViz. This list includes: wet/dry detention ponds (including bioretention practices), constructed wetlands, riparian buffers, vegetative filter strips, and revegetation. These restoration/rehabilitation practices were then incorporated in the Model. The R&R practices and corresponding removal efficiencies can be found in Table 3. The five restoration/rehabilitation practices correspond with stakeholder issues and are consistent with NC-CREWS functional rehabilitation goals, and are recognized as appropriate BMPs for reduction of nonpoint-source pollution. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 13

18 Table 3: Effectiveness of Functional Restoration and Rehabilitation Practices for Control of Runoff In Wetlands and Riparian Areas Restoration or Rehabilitation Practice R&R 1 Constructed Wetland R&R 2 Vegetated Filter Strip R&R 3 Wet/Dry Detention Pond R&R 4 Forested Riparian Buffer (30m) R&R 5 Revegetation of Former Wetland Removal Efficiency (%) Total Suspended Solids Total Nitrogen Total Phosphorus Range Average Range Average Range Average References Wotzka and Oberts, 1988; Oberts et al., 1989; Rhodes et al., 1985; Barten, 1987; Rushton and Dye, 1990; Glick, et al.; 1991; Reed, 1991; Schiffer, Barten, 1987; Hartigen et al., 1989; EPA, 1983; Casman, 1990; Glick, et al., 1991; Dilaha et al., Schueler, 1987; Scheuler, et al., 1992; Martin, 1988; MWCOG, 1983; Wotzka and Oberts, 1988; Holler, Phillips, 1989; Correll and Weller, 1989; Cooper, et al., 1987; Lowrence, et al., 1983, 1984; Jacobs and Gilliam, 1985; Cooper and Gilliam, Wotzka and Oberts, 1988; Oberts et al., 1989; Rhodes et al., 1985; Barten, 1987; Rushton and Dye, 1990; Hay and Barrett, 1991; Glick, et al., 1991; Schiffer, 1990 Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 14

19 A description of the selected restoration/rehabilitation practices is as follows: Constructed Wetland. Engineered systems designed to simulate natural wetlands to exploit the water purification functional value for human use and benefits. Constructed wetlands consist of former upland environments that have been modified to create poorly drained soils and wetlands flora and fauna for the primary purpose of contaminant or pollutant removal from wastewaters or runoff. Constructed wetlands are essentially stormwater treatment systems and are designed and operated as such though many systems do support other functional values (Hammer, 1992). Vegetated Filter Strip. Created areas of vegetation designed to remove sediment and other pollutants from surface water runoff by filtration, deposition, infiltration, adsorption, absorption, decomposition, and volatilization. A vegetated filter strip is an area that maintains soil aeration as opposed to a wetland that, at times, exhibits anaerobic soil conditions (Dillaha et al., 1989a). Detention Pond. Constructed or converted wet or dry detention ponds for surface water runoff management that provides both peak volume control and water quality and habitat benefits. This practice includes small bioretention structures (rain gardens). The design of these detention ponds can be modified to include decreasing the size of the outlet to increase the detention of the dry pond. A dry pond's outlet may also be modified to detain a permanent pool of water and thus create a wet pond or extended detention wet pond. Aquatic vegetation can be planted along the perimeter of constructed wet ponds or other open water systems to enhance sediment control and provide some biological pollutant uptake (USEPA, 2003). Vegetated Buffers. Vegetated buffer strips are strips of vegetation separating a waterbody from a landuse to prevent nonpoint pollution source inputs. Vegetated buffers are variable in width and can range in function from a vegetated filter strip to a wetland or riparian area. For purposes of the functional rehabilitation plan, the term vegetated buffer refers to natural riparian areas that are either set aside or restored to filter pollutants from runoff and to maintain the ecological integrity of the waterbody and the land adjacent to it (Nieswand et al., 1989). Revegetation. Constructed strips of vegetation used in various settings will remove pollutants in runoff from a developed site (Nieswand et al., 1989). These areas are reconstructed to provide a rough surface containing a heterogeneous mix of ground cover, including herbaceous and woody species of vegetation (Stewardship Incentive Program, 1991; Swift, 1986). This mix of vegetation allows the buffer to function more like a wetland or riparian area (USEPA, 2003). Design criteria for the restoration/rehabilitation practices are discussed in the next section Functional Improvement Indicators The sixth component of the conceptual model introduces indicators of change that are measured and compared electronically in order to predict the relative effectiveness of potential restoration/rehabilitation practices. To develop this capability, the R&R practices were evaluated relative to the NC-CREWS functional assessment protocol. R&R practices that indirectly pertain to watershed functions (i.e., R&Rs pertaining to source reduction, timing of various landuse Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 15

20 practices (e.g., crop rotation), education or behavioral change, etc.) were not considered. Indicators used in the conceptual model focus primarily on percent reduction in sediment and nutrients (total nitrates and phosphates) as these are the primary nonpoint source pollutants measured on site and regulated by state water quality rules and are addressed by specific R&Rs. By using a metric like percent reduction, two objectives of the conceptual model can be met. First, opportunities for functional improvement in the watershed can be compared using known targets for reductions in pollutants. Secondly, a range of target reductions can be incorporated so that a user of the conceptual model can vary strategies for restoration/rehabilitation practices for different target results or mix and match restoration and/or rehabilitation practices to achieve a desired outcome. Various design assumptions were used to develop indicators for the restoration/rehabilitation practices identified in section Because wetland and riparian areas should be considered as part of a continuum of filters along rivers, streams, and coastal waters that together serve an important nonpoint source abatement function, the following assumptions were made: 1. A wet and/or extended detention pond should be designed to accommodate runoff from a 2- year, 24-hour storm event. Satisfactory pollutant removal performance can be achieved if ponds are sized at least 2 percent of the contributing drainage area, with an average depth of 6 feet (Wu, 1989). To achieve maximum efficiency, the total drainage area should be a minimum of 25 acres (Scheuler and Holland, 2000; Scheuler, et al., 1992; Holler, 1989; Martin, 1988; Wotzka and Oberts, 1988; Schueler, 1987; MWCOG, 1983). Many local communities require detention ponds that accommodate a 100-year storm event. The size (volume) is calculated by multiplying the predicted precipitation in acre-feet times the number of acres in a study area. A detention pond should be considered pretreatment only. 2. A constructed wetland should be designed to accommodate runoff from a 2-year, 24-hour storm event. Drainage area minimum is 25 acres and the size of the wetland should provide no less than 0.1 watershed-inch stormwater storage (Glick, et al., 1991; Reed, 1991; Rushton and Dye, 1990; Schiffer, 1990; Oberts et al., 1989; Wotzka and Oberts, 1988; Barten, 1987; Rhodes et al., 1985). A constructed wetland should be designed to provide a variety of water quality, hydrological, and habitat values. At a minimum, it must provide stormwater retention, comparable to a detention pond. There is also some evidence that the pollutant removal performance of wetlands in general declines over time, particularly for total phosphorus. 3. A forested riparian buffer should be no less than 30 meters (100 feet) wide between the upland and surface water bodies for each parcel. However, the consideration of a 50-foot wide buffer may be easier to recruit and support. In some areas, the entire 100-year floodplain should be a buffer (Phillips, 1989; Correll and Weller, 1989; Cooper et al., 1987; Cooper and Gilliam, 1987; Jacobs and Gilliam, 1985; Lowrence, et al., 1983,1984). This could be a revegetation or setting aside existing riparian forest. The R&R practice makes no distinction as long as an appropriate vegetative species composition is used. Application of this R&R practice is considered most practical at the parcel level. It is more likely that a single landowner would preserve existing vegetation rather than a group of landowners. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 16

21 4. A vegetated filter strip (including grassed swales and bioretention filters) should be no less than 30 meters (100 ft) wide between the upland and surface water bodies. It should be as long as the width of the adjacent contributing area or each parcel of land, whichever is longer (Glick, et al., 1991; Casman, 1990; Dilaha, et al., 1989; Hartigen, et al., 1989; Barten, 1987; EPA, 1983). Notes: A filter strip should not be located in an area with greater than a 5 percent slope. A filter strip should be considered pretreatment only. Drainage area maximum is 5 acres as sheet flow generally cannot be maintained over large distances (150 feet for pervious areas; 75 feet for impervious areas). 5. Revegetation of a former wetland should be designed to accommodate runoff from a 2-year, 24-hour storm event and should contain a buffer between the upland and surface water (Glick, et. al., 1991; Hay and Barrett, 1991; Rushton and Dye, 1990; Schiffer, 1990; Oberts, et al., 1998; Wotzka and Oberts, 1988; Barten, 1987; Rhodes, et al., 1985). This is a special case when a former wetland is identified. The DCM wetland classification data set includes information about prior converted farmland that formerly functioned as a wetland from the National Wetlands Inventory maps (NWI). A map depicting areas that were formerly performing watershed functions as various types of wetlands can be found in the PRLWCR (Figure 9). Many of the assumptions used in the Model to develop indicators for each of the restoration and /or rehabilitation practices, as well as the projected effectiveness of the R&Rs, are based on calculating or estimating the percentage of impervious cover and the volume of runoff generated per unit area. The metric for estimating impervious cover for different landuse types within the Pasquotank River Local Watershed Planning Area was based on guidelines developed by Cappiella and Brown (2001). These guidelines are shown in Table 4. The calculation for estimating the volume of runoff generated per unit area was developed from Scheuler and Holland (2000). Table 4. Estimating Percentage of Impervious Cover. Landuse/Impervious Cover Relationships (From Cappiella and Brown, 2001) Landuse Category Impervious Cover (%) Forest 0.0 Agriculture Acre Lot Residential Acre Lot Residential /2 Acre Lot Residential /4 Acre Lot Residential /8 Acre Lot Residential 32.6 Townhome Residential 40.9 Multifamily Residential 44.4 Light Industrial 53.4 Commercial 72.2 Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 17

22 4.0 Data Development Process Data collection, compilation, and refinement can be an expensive, time-consuming task in the development of a GIS-based information system and process model. The focus of the data identification and collection process was to obtain only data necessary to measure and analyze indicators of change that were derived from NC-CREWS functions (water quality, hydrology, habitat, and risk of loss) to address stakeholder issues, and to meet requirements outlined under best management practice guidelines to be used in developing appropriate restoration and rehabilitation practices. The indicators, attributes, and constraints as defined in the conceptual model to be measured in the Functional Rehabilitation Model are in Table 1 at the end of this report. Since original data collection was beyond the scope of the project, the majority of the databases used in the model were obtained from state and federal data archives. Data requirements were established after review of North Carolina Division of Coastal Management (NCDCM) and Division of Water Quality (DWQ) reports including NC-CREWS, the Wetland Analysis Protocol, and the Neuse River/Tar-Pamlico Basin studies, results from the stakeholder meetings, and United States Environmental Protection Agency (USEPA) best management practices for nonpoint-source pollution in coastal regions. The process of impact assessment also provided guidance for the data collection effort as well as the development of the Model. General categories of data used in the Model included current landuse and land (vegetative) cover, Division of Coastal Management (DCM) wetland maps, digital soil inventories, location of sensitive and protected habitat areas including known populations of endangered or threatened species, surface hydrology (wetlands and riparian areas), geographical and legal boundary data and other line files (local and county jurisdictions, highways, utility infrastructure, etc.), slope, aerial photographs, and other data sets that can be used to compare alternative scenarios. Compilation of the database was tracked using a data dictionary. The data dictionary provides a reference of data obtained, where the data originated, and how the data would be used in the Watershed Characterization Report, the Model, the water quality models (AVGWLF and BASINS), and so on. Each database was reviewed to determine areas of coverage, scale, and accuracy in order to identify any data gaps. The current version of the data dictionary is provided in Appendix C. 5.0 Stakeholder Participation and Issues Identification Public involvement in an assessment process creates an environment for understanding, acceptance, and support for the recommended strategies. The Stakeholders were introduced to the concepts of functional replacement for impacted watershed functions. The basis for this understanding was derived from the NC-CREWS model. The project team worked with the stakeholders in a modified Delphi process to rank issues identified by the stakeholders across the watershed and subcatchments. The Stakeholder Issue Book and Rankings, which included issue ranking, was used in the preparation and development of the Pasquotank River Watershed Goals and Management Strategies and the Subcatchment Management Strategies found in the PRLWCR. This information is used in conjunction with the Model to identify management strategies for the watershed and subcatchments. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 18

23 6.0 Site Restoration and Rehabilitation Potential The Model will be used to help analyze potential project areas, which will address watershed and subcatchment nutrient/sediment reduction goals for the watershed and individual subcatchments. This information combined with the Stakeholder Issue Book and Ranking establishes the watershed functional rehabilitation goals, which are outlined in Section 11 of the PRLWCR. This report also assists Stakeholders in identifying potential restoration/rehabilitation (R&R) practices for project areas that are on a scale which will provide for measurable watershed improvements. Each site identified can be analyzed by the Model, and this information will be confirmed and supplemented by an onsite visual assessment protocol, which completes the data set necessary to decide if the project sites are feasible and will address the watershed functional rehabilitation goals. The onsite visual assessment will also test the veracity of the Model and allow for adjustments. In some cases, an onsite visual assessment is difficult to achieve due to the location of the opportunity area and lack of authorization from property owners to enter the property. In these cases, the information obtained from the Model only is utilized to determine functional assets and deficits and corresponding potential restoration/rehabilitation practices that could be implemented to restore, enhance, and/or create watershed functions. This information provides an initial understanding of opportunity potential until a more in-depth onsite visit is obtainable. 7.0 CommunityViz Background The Model was developed in the CommunityViz software framework, which was developed by the Orton Family Foundation and is a commercial, off-the-shelf Geographic Information System (GIS) based planning and decision support application. The software uses the data handling and visualization capabilities of GIS to enhance decision maker insight and create scenario-driven analyses that evaluate the implications and opportunities of alternative strategies for economic development, land-use and transportation planning, facilities management, environmental risk assessment, remediation and protection, energy forecast, water allocation, and resource control. Driven by user-defined algorithms and assumptions, these systems provide high decision quality, focused investigation of issues at hand, and consistent comparison among alternative planning strategies. The Scenario Analysis Tool provides the underlying framework for the powerful alternative-comparison capabilities of CommunityViz. It also provides a rich set of quantitative impact analysis capabilities, offering the functionality of a spatial spreadsheet that can perform numerical computations on geographic data in real time. 7.1 Introduction to the CommunityViz Software Framework The CommunityViz software is an ArcView extension and contains a suite of three modules; Scenario Constructor, SiteBuilder3D, and Policy Simulator. The Pasquotank River Watershed Functional Rehabilitation Model was developed specifically utilizing the CommunityViz Scenario Constructor module. Scenario Constructor is the core module of CommunityViz and provides impact analysis capabilities featuring the functionality of a spatial spreadsheet that can perform numerical computations on geographic data in real time. Scenario Constructor allows users to create maps, charts, and reports showing alternative scenarios based upon information contained within the GIS enterprise system and other assumptions (CommunityViz Course Training Manual). Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 19

24 Pricing information for Scenario Constructor Module (stand-alone), along with the three-module suite can be found at or by contacting the sales department. 7.2 CommunityViz Hardware and Software Requirements The following is a generalized list of hardware requirements and options needed to run CommunityViz; MHz Intel compatible, Pentium II or higher CPU 256 MB RAM High-end graphics card (Minimum 32 MB RAM) supporting OpenGL 400 MB free disk space for installation 2 GB for data 3-button mouse (preferred) Windows NT 4.0 service pack or higher or Windows 2000 The following is a generalized list of software requirements and options needed to use CommunityViz; Application Software ArcView 3.2 ArcView Spatial Analyst 2.0 ArcView 3D Analyst (optional to support TINs for use in SiteBuilder3D) CommunityViz Operating Systems Windows NT (Service Pack 4) Windows Data Requirements for Scenario Constructor Scenario Constructor utilizes typical GIS layers, such as; Roads Rivers Parcels Zoning Imagery User Created data layers Note: Scenario Constructor, like most GIS applications, is data-centric. Thus, as in any GIS application, the usefulness of Scenario Constructor is dependant on the depth and condition of the GIS database. Implementing Scenario Constructor will require certain basic data layers to be present, as well as basic tabular data fields, but you can also create and edit your own GIS data while using Scenario Constructor (CommunityViz Training Manual). Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 20

25 8.0 Components of the Pasquotank River Local Watershed Functional Rehabilitation Model 8.1 CommunityViz Scenario Constructor Framework The Scenario Constructor module of CommunityViz adds a decision framework to ArcView GIS to assist in framing many landuse decisions by using basic decision elements, such as determining goals and objectives, defining the problem and potential causes, identifying and evaluating alternative solutions, implementing the best alternative and finally re-evaluating the results. There are two basic users of Scenario Constructor; Scenario Exploration Users, which simply explore decision alternatives, based on existing scenarios, and Scenario Setup Users, who create and/or modify existing scenarios and would need to be more experienced in manipulating ArcView views, themes, and tables along with some familiarity with ArcView Field Calculator or Avenue scripting. A Scenario is a View (like in ArcView) with additional information elements attached that implement a decision framework. A Scenario is made up of fundamental data sets and definitions and formulas, which define the objectives, assumptions, and constraints of a particular decision. There are four key components of CommunityViz Scenario Constructor: indicators, assumptions, constraints, and auto data. These components are defined below and described in more detail in Sections through Indicators are measurable or computed values that represent specific scenario goals. Indicators can be set up into categories, such as infrastructure, landuse, etc. and indicators can be graphed. Indicators are scenario-based computations and are set up in the Scenario View Properties under the View dropdown menu. Assumptions/Variables - are values for the indicators that can be challenged or changed. Assumptions are based on literature and best professional judgment. Assumptions are also found in the View dropdown menu under Scenario View Properties. Constraints Scenario specific set of rules and regulations established due to physical, biological, chemical, legal, or other impediments. Constraints are found under the Theme dropdown menu. Auto Data the core information for the Scenario and applies to automated themes, which are themes that are created for analysis and can be edited or modified. 8.2 Pasquotank River Scenario Framework The Pasquotank River Scenario within the Model is a turbo-charged View with additional information elements attached, which allow a user to view, manipulate and analyze potential restoration and/or rehabilitation practices to improve the overall watershed functions within the Pasquotank River Local Watershed Planning Area. A copy of the User Guide can be found in Appendix A Pasquotank River Scenario Indicators The indicators in the Pasquotank River Scenario are total nitrogen, total phosphorous, and sediment and are watershed characteristics that can be measured and monitored. These indicators are measurable components of the watershed functions (water quality, hydrology, and habitat). Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 21

26 The indicators can be graphed on bar scales to show potential watershed changes from new projects as a result of implemented restoration and rehabilitation practices. Therefore, the indicators show how a new watershed project could improve the overall functional quality of the watershed. These indicator(s) are organized under specific functional categories, the units to be measured (minimum and maximum values), target values (goals) and target labels. An example of an indicator is Nitrogen Compound. The indicator for Nitrogen Compounds has the description Nitrogen compounds delivered in pounds per acre per year from the proposed restoration or enhancement site to the subcatchment, (Revised Pasquotank River Local Watershed Characterization Plan, 2003). The units are lbs/acre/yr. The minimum value is set at 0 and the maximum is set at 7 as an arbitrary scale from least to most. The target levels are set at 6.1 and the label is Current Baseline. The assignments of these numbers are derived from information contained in the PRLWCR. After the necessary information for each indicator is compiled, each indicator can be graphed to visually show the anticipated results associated with a new project. Each indicator can be charted separately or cumulative indicators can be charted. The chart(s) can be created for the watershed, subcatchment, or a portion of the subcatchment Pasquotank River Scenario Assumptions The assumptions (also known as variables) in the Pasquotank River Scenario are based on watershed objectives and are created through literature, best professional judgment, and stakeholder input. For example, one assumption says that a restoration/rehabilitation practice that reduces sedimentation will result in an increase in water quality. The assumptions in this scenario are all percent reductions for the restoration and rehabilitation practices (revegetation, constructed wetlands, vegetative filter strips, wet detention ponds, and riparian buffers which include shoreline stabilization measures), which are derived from the North Carolina Division of Water Quality (NCDWQ) document for the Tar-Pamlico and Neuse River Nutrient Reduction Goals and the Environmental Protection Agency (EPA) document, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters. These assumptions require a description, a category, a value, units, and minimum and maximum values, which is similar to the indicators. For example one assumption/variable is Constructed Wetlands Sediments. Its description is percent reduction of sediment by constructed wetlands. Average percentage based on literature reviewed (Table 18 in Revised PRLWCR for removal efficiencies). The value is set at 60% reduction within the range of 0 for the minimum value and 80 for the maximum. Because these assumptions are based on literature, best professional judgment, and stakeholder input, they can be challenged. CommunityViz allows the user to change the assumptions within the minimum and maximum range for enhanced alternative analysis. For example, if the user does not agree that a constructed wetland reduces sediment by 60%, the user can change the assumptions to another reduction percentage within the minimum/maximum range and review the effects of that change on the indicator charts. Changing the assumptions allows the user to compare alternatives Pasquotank River Scenario Constraints The constraints in the Pasquotank River Scenario are factors (physical, chemical, biological, social, economic, regulatory, etc.) that must be considered when evaluating resources to be managed or for management actions. The constraints also serve as alerts to particular aspects of an area that has low functions according to NC-CREWS. These alerts display the functions that Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 22

27 could be improved by a potential project. Constraints require a description, a category, and a formula, which is in the form of If the value of some data is X, then display this constraint violation. The formulas for constraints and auto data can be created using an Edit Wizard, which is provided by CommunityViz Scenario Constructor. Constraints also require the user to determine if the constraint is to be displayed or hidden in the menu, and determines what message is to be displayed. For example, one constraint in the Pasquotank River Scenario is for Runoff Storage. The description says, Display an alert message if Wetland Size (A2) RANK =.3 OR Wetland Size (A2) RANK =.1, which describes the minimum and maximum size of the wetland area. The constraint is recognized and the alert message reads, Proposed restoration or enhancement site does not contain sufficient wetland area to decrease peak floodwater discharge. There are similar constraints for other watershed functions and other minimums and maximums associated with those functions and are based on NC-CREWS data Pasquotank River Scenario Auto Data The auto data in CommunityViz is essentially the core of all information the Model operates from and is utilized in the Pasquotank River Scenario. The auto data are manually entered in the Scenario Theme Properties and only apply to automated themes (themes that are created for analysis). For example, in the Pasquotank River Scenario the automated theme New Watershed Project one of the auto data that is created for that theme is wetland size. Each auto data has a description, a category, a formula, units, and a visibility option. The wetland size auto data has the description, Area of the proposed restoration or enhancement site, under the general category, with the formula [Shape].ReturnArea * #Acres per Sq Meter#, and acres as the units. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 23

28 9.0 References ABAG Treatment of Stormwater Runoff by a Marsh/Flood Basin: Interim Report. Association of Bay Area Governments, in association with Metcalf & Eddy, Inc. and Ramlit Associates, Berkeley, CA. Barten, J.M Stormwater Runoff Treatment in a Wetland Filter: Effects on the Water Quality of Clear Lake. Lake and Reservoir Management, 2: Cappiella, K. and K. Brown, Land Use and Impervious Cover in the Chesapeake Region, Watershed Protection Techniques 3(4): Casman, E Selected BMP Efficiencies Wrenched from Empirical Studies. Interstate Commission on Potomac River Basin. Cooper, J.R., J.W. Gilliam, R.B. Daniels, and W.P. Robarge Riparian Areas as Filters for Agriculture Sediment. Soil Science Society of America Journal, 51(6): Cooper, J.R., and J.W. Gilliam Phosphorus Redistribution from Cultivated Fields into Riparian Areas. Soil Science Society of America Journal, 51(6): Cooper, J. R., J. W. Gilliam, and T. C. Jacobs Riparian Areas as a Control of Nonpoint Pollutants. In Watershed Research Perspectives, ed. D. Correll, Smithsonian Institution Press, Washington, DC. Correll, D.L., and D.E. Weller Factors Limiting Processes in Freshwater: An Agricultural Primary Stream Riparian Forest. In Freshwater Wetlands and Wildlife, ed. R.R. Sharitz and J.W. Gibbons, pp U.S. Department of Energy, Office of Science and Technology, Oak Ridge, Tennessee. DOE Symposium Series #61. Dillaha, T.A., J.H. Sherrard, and D. Lee Long Term Effectiveness of Vegetative Filter Strips. Water Environment and Technology, 1: Dillaha, T.A., R.B. Renear, S. Mostaghimi, and D. Lee. 1989a. Vegetative Filter Strips for Agricultural Nonpoint Source Pollution Control. Transactions of the American Society of Agricultural Engineers, 32(2): Glick, R., M.L. Wolfe, and T.L. Thurow Urban Runoff Quality as Affected by Native Vegetation. Presented at the 1991 International Summer Meeting sponsored by American Society of Engineers, Albuquerque, NM. ASAE Paper No Hammer, D.A Designing Constructed Wetlands Systems to Treat Agricultural Nonpoint Source Pollution. Ecological Engineering, 1(1992): Harper, H.H., M.P. Wanielista, B.M. Fries, and D.M. Baker Stormwater Treatment by Natural Systems. STAR project # Final Report. Florida Department of Environmental Regulation, Tallahassee. Hartigen, J.P., T.S. George, T.F. Quasebarth, and M.E. Dorman Retention, Detention, and Overland Flow for Pollutant Removal from Highway Stormwater Runoff. Vol. II Design Guidelines. Federal Highway Administration. Report No. FHWA/RD-89/203. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 24

29 Hey, D.L., and K.R. Barrett Hydrologic, Water Quality, and Meteorologic Studies. In The Des Plaines River Wetlands Demonstration Project, Final Draft Report to the Illinois Department of Energy and Natural Resources. Wetlands Research, Inc., Chicago, IL. Hickok, E.A., M.C. Hannaman, and N.C. Wenck Urban Runoff Treatment Methods: Volume I - Non-Structural Wetland Treatment. U.S. Environmental Protection Agency, Office of Research and Development, Municipal Environmental Research Laboratory, Cincinnati, OH. EPA-600/ Holler, S Buffer Strips in Watershed Management. In Watershed Management Strategies for New Jersey, Cook College Department of Environmental Resources and New Jersey Agricultural Experiment Station, Rutgers University, New Brunswick, NJ, pp Jacobs, T.C., and J.W. Gilliam Riparian Losses of Nitrate from Agricultural Drainage Waters. Journal of Environmental Quality, 14(4): Lowrance, R., R. Leonard, and J. Sheridan Managing Riparian Ecosystems to Control Nonpoint Pollution. Journal of Soil and Water Conservation, 40(1): Lowrance, R.R., R.L. Todd, and L.E. Assmussen Nutrient Cycling in an Agricultural Watershed: Phreatic Movement. Journal of Environmental Quality, 13(1): Lowrance, R.R., R.L. Todd, and L.E. Asmussen Waterborne Nutrient Budgets for the Riparian Zone of an Agricultural Watershed. Agriculture, Ecosystems and Environment, 10: Martin, E.H Effectiveness of an Urban Runoff Detention Pond-Wetlands System. Journal of Environmental Engineering, 114(4): Mitsch, W.J. and J.G. Gosselink Wetlands, Van Nostrand Reinbold, New York. MWCOG Urban Runoff in the Washington Metropolitan Area: Final Report Washington, D.C. Area Urban Runoff Project. Prepared for U.S. Environmental Protection Agency, Nationwide Urban Runoff Program, Washington, DC. Nieswand, G.H., B.B. Chavooshian, R.M. Hordon, T. Shelton, S. Blarr, and B. Brodeur Buffer Strips to Protect Water Supply Reservoirs and Surface Water Intakes: A Model and Recommendations. Cook College Department of Environmental Resources for the New Jersey Department of Environmental Protection. North Carolina Department of Environment and Natural Resources, North Carolina Coastal Region Evaluation of Wetland Significance (NC-CREWS), Strategic Plan for Improving Coastal Management in North Carolina. Division of Coastal Management. North Carolina Department of Transportation NCDOT Erosion and Sediment Control Manual - New Standards. North Carolina Division of Coastal Management, Wetland Analysis Protocol for Restoration and Enhancement. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 25

30 North Carolina Division of Water Quality. 1999, Neuse River Basin: Model Stormwater Program for Nitrogen Control. North Carolina State University Evaluation of the North Carolina Erosion and Sedimentation Control Program. North Carolina Sedimentation Control Commission, Raleigh. pp. V6-V13. Oberts, G., P.J. Wotzka, and J.A. Hartsoe The Water Quality Performance of Select Urban Runoff Treatment Systems: Part One of a Report to the Legislative Commission on Minnesota Resources. Metropolitan Council of the Twin Cities Area, St. Paul, MN. Pub. No a. Phillips, J.D Nonpoint Source Pollution Control Effectiveness of Riparian Forests Along a Coastal Plain River. Journal of Hydrology, 110 (1989): Peterjohn, W.T., and D.L. Correll Nutrient Dynamics in an Agricultural Watershed: Observations on the Role of a Riparian Forest. Ecology, 65: Reed, S.C Constructed Wetlands for Wastewater Treatment. BioCycle: Journal of Waste Recycling. Rushton, B.T., and C. Dye Hydrologic and Water Quality Characteristics of a Wet Detention Pond. In The Science of Water Resources: 1990 and Beyond, November 4-9, 1990, ed. M. Jennings. American Water Resources Association, Betesda, MD. Schiffer, D. 1990a. Wetlands for Stormwater Treatment. U.S. Geological Survey and the Florida Department of Transportation, Tallahassee. Schiffer, D. 1990b. Impact of Stormwater Management Practices on Groundwater. U.S. Geological Survey and the Florida Department of Transportation, Tallahassee. Schueler, T.R Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs. Metropolitan Washington Council of Governments, Washington, DC. Schueler, T.R., J. Galli, L. Herson, P. Kumble, and D. Shepp Developing Effective BMP Strategies for Urban Watersheds. In Nonpoint Source Watershed Workshop, September 1, 1991, Seminar Publication, pp U.S. Environmental Protection Agency, Washington, DC. EPA/625/4-91/027. Schueler, T.R., P.A. Kumble, and M.A. Heraty A Current Assessment of Urban Best Management Practices: Techniques for Reducing Non-Point Source Pollution in the Coastal Zone. Department of Environmental Programs, Metropolitan Washington Council of Governments, Washington, DC. Scheuler, T.R. and H.K. Holland, The Practice of Watershed Protection. Center for Watershed Protection, Ellicott City. Maryland. Schueler, T.R., and J. Lugbill Performance of Current Sediment Control Measures at Maryland Construction Sites. Metropolitan Washington Council of Governments, Washington, DC. Schueler, T Controlling Urban Runoff: A Practical Manual for Planning and Designing Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 26

31 Urban BMPs. Metropolitan Washington Council of Governments, Washington, DC. Stewardship Incentive Program Riparian Forest Buffer, pp and Swift, L.W., Jr Filter Strip Widths for Forest Roads in the Southern Appalachians. Southern Journal of Applied Forestry, 10(1): USEPA, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters ( Accessed in July USEPA Final Report of the Nationwide Urban Runoff Program. U.S. Environmental Protection Agency, Water Planning Division, Washington, DC. Welinski and Stack, Baltimore Department of Public Works Detention Basin Retrofit Project and Monitoring Study Results. Water Quality Management Office, Baltimore, MD. Wotzka, P., and G. Oberts The Water Quality Performance of a Detention Basin-Wetland Treatment System in an Urban Area. In Nonpoint Pollution: Policy, Economy, Management, and Appropriate Technology, pp American Water Resources Association, Bethesda, MD. Pasquotank River Local Watershed Functional Rehabilitation Model Report December 2003 DSPro Project No.: DSP Page 27

32 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts I. WATER QUALITY IA. Nonpoint Source Function - Prevention or removal of particulates, nutrients, or toxins from surface water runoff. Runoff - Proximity to Source (A1) Prevention Proximity to sources considers the likelihood of H - >20% perimeter agriculture + developed; M - Runoff Prevention polluted runoff entering the >20% perimeter agriculture wetland based on + developed + pine predominant adjacent land plantation; L - </= 20% uses. The more of the perimeter of the wetland surrounded by nonpointsource-producing perimeter agriculture + developed + pine plantation. land uses, the higher the rating. Proposed restoration or enhancement site is not located in areas where land use activities can be modified to reduce sources of NPS pollution. Proximity of surrounding land uses Runoff - Proximity to Water Body (A2) Retention Proximity to surface water body is an indicator of the likelihood that polluted H - Within 300 ft. of permanent surface water; M - Within 300 ft. of Runoff Retention runoff entering the wetland intermittent surface water; L would otherwise enter surface water. Wetlands close to permanent - > 300 ft. from permanent or intermittent surface water. surface water are rated High; those close to intermittent streams are rated Moderate; and those not close to any surface water are rated Low. Proposed restoration or Water body: enhancement site is not permanent and located within 300 ft. of a intermittent surface permanent or intermittent water surface water body. Retention of runoff function will not be achieved. Runoff - Proximity to Headwaters; stream order (A3) Runoff - Site Conditions, Wetland Type (A4a) Removal Removal The "higher" in its H - Intermittent or first order watershed a wetland lies. stream; M - Second or third The greater is the potential order stream; L - Higher effect of NPS removal on than third order stream. overall watershed quality. Site conditions are determined by the biotic and physical structure typical of the wetland type and by the properties of the predominant underlying soil. Wetland type (4a) breakdowns are based on field data on indicators of wetland capacity for nutrient transformation and processing and removal of sediment and dissolved materials. H - Bottomland hardwood, swamp forest, headwater swamp; M - Freshwater marsh, pine flat, hardwood flat, pocosins, maritime forest; L - Pine plantations, altered sites Runoff Removal Runoff Removal Proposed restoration or enhancement site does not contain wetlands that will enhance water quality by acting as traps for nutrients and sediments in polluted runoff. Proposed restoration or enhancement site does not contain a wetland capacity for nutrient transformation and processing and removal of sediment and dissolved materials. Stream order classification Wetland Type Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

33 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Runoff - Site Conditions, Soil (A4b) Removal The finer the texture and the higher the organic matter content of the soil, the higher its cation H - Histosol or frequently flooded mineral soil with high clay and organic matter; M - Infrequently Runoff Removal exchange capacity and the flooded mineral soil with more effective it is in retaining transforming nutrients. high clay and organic matter; L - Infrequently flooded mineral soil with low clay and organic matter. Proposed restoration or Soils: Histosols, enhancement site is not frequently flooded located in an area where with high clay and organic matter content of organic matter the soil and its cation exchange capacity would be effective in retaining or transforming nutrients. IB. Floodwater Cleansing Function Flooding - Water Source (B1a) Removal of Water source and sediments, nutrients, proximity to sources toxins that have indicates whether already entered pollutants are likely to be surface water. present in a stream. H - In floodplain of Pollutant removal Piedmont-draining stream or upstream HU > 50% agricultural + developed; M - In floodplain of coastal plain draining stream w/ upstream HU < 50% agricultural + developed; L - Not in floodplain. Proposed restoration or Location of stream in enhancement site is not HU; Surrounding located adjacent to land use degraded streams (arising in Piedmont) and would not have the capacity to intercept and cleanse sediments, nutrients, and toxins in surface waters that enter a wetland through overbank flow. Flooding - Water Source (B1b) Removal of Water source and sediments, nutrients, proximity to sources toxins that have indicates whether already entered pollutants are likely to be surface water. present in a stream. H - > 25% of stream length in HU bordered by agricultural or developed land; M % of stream length bordered by agricultural or developed land; L - < 5% of stream length bordered by agricultural or developed land. Pollutant removal Proposed restoration or Location of stream in enhancement site is not HU; Surrounding located adjacent to land use degraded streams (from local upstream sources) and would not have the capacity to intercept and cleanse sediments, nutrients, and toxins in surface waters that enter a wetland through overbank flow. Flooding - Duration (B2) Removal The longer floodwater remains in a wetland, the greater is the level of pollutant removal that occurs. H - Wetland is flooded 'long to very long' periods; M - Wetland is flooded 'brief' periods; L - Wetland is flooded 'very brief' periods or not at all. Pollutant removal Same Floodplain boundaries Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

34 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Site Conditions - Wetland Type and Soil (B3a) Removal Wetland type breakdowns H - Bottomland hardwood, are based on field data of swamp forest; L - Other indicators of capacity for wetland types. nutrient transformation and processing, removal of dissolved materials, organic carbon transport, and retention of woody materials to provide onsite energy sources for microbial activity. Pollutant removal Same Wetland type Site Conditions - Wetland Type and Soil (B3b) Removal The finer the texture and the higher the organic matter content of the soil, the higher is its cation H - Histosol or frequently flooded mineral soil with high clay and organic matter; M - Infrequently Pollutant removal exchange capacity and the flooded mineral soil with more effective it is in high clay and organic retaining and transforming matter; L - Infrequently nutrients and toxins. flooded mineral soil with low clay and organic matter. Proposed restoration or Soils: Histosols, enhancement site is not frequently flooded located in an area where with high clay and organic matter content of organic matter the soil and its cation exchange capacity would be effective in retaining or transforming nutrients. Width of Wetland Perpendicular to Stream (B4) Removal The wider a wetland is along a stream, the more area there is available for water retention and pollutant removal. H - > 100 ft.; M ft.; L < 50 ft. Pollutant removal Proposed restoration or Wetland size enhancement site is not located adjacent to degraded streams (from local upstream sources) and would not have the capacity to intercept and cleanse sediments, nutrients, and toxins in surface waters that enter a wetland through overbank flow. Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

35 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts II. HYDROLOGY IIA. Surface Runoff Storage Watershed Position (A1) Storage Wetlands along headwater H - Intermittent or first order streams receive stream; M - second or third proportionately more order stream; L - > third overland runoff than order stream. downstream wetlands, and their position high in the watershed results in their water storage capacity having greater impact on overall watershed hydrology. Runoff Storage Proposed restoration or Wetland location enhancement site is not adjacent to a permanent or intermittent surface water body. Storage of runoff function will not be achieved. Wetland Size (A2) Storage Based on hydrologic modeling, the water storage capacity of a wetland equal in size to H - Wetland is >.54% of total HU area; M - Wetland is % of HU area; L - Wetland is <.05% of HU Runoff Storage.54% of total wetland area area. will result in a decrease in peak discharge of 1%. Water storage in a wetland less than.05% of the watershed area will result in a decrease in peak discharge of less than.1% Site Condition, Wetland Type (A3a) Storage Wetland type breakdown are based on field data on such indicators of surface water storage capacity as microtopographic complexity, evidence of soil reduction, and evidence of standing water. H - Bottomland hardwood, Runoff Storage swamp forest, headwater swamp, freshwater marsh; M - Hardwood flat, pocosin, maritime forest; L - Pine flat, pine plantation, altered site. Proposed restoration or enhancement site does not contain sufficient wetland area to decrease peak floodwater discharge. Proposed restoration or enhancement site does not contain a wetland with sufficient storage capacity for nutrient transformation and processing and removal of sediment and dissolved materials. Wetland size Wetland type Site Condition, Soil Infiltration (A3b) Storage The infiltration capacity of H - Soil Hydrologic group A, Runoff Storage the underlying soil B, or A/D; M - Soil determines the amount of Hydrologic group C, or B/D; water the soil can receive L - Soil Hydrologic group D. and store before additional water will run off. Hydrologic groups are used in soil surveys to indicate a soil's capacity for water intake when the soils are wet and receive precipitation from longduration storms. Proposed restoration or enhancement site does not have soils with sufficient storage capacity for nutrient transformation and processing and removal of sediment and dissolved materials. Soils: hydrologic group Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

36 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts IIB. Floodwater Storage Duration of Flooding (B1) Storage Duration of flooding is a measure of the length of time the soil surface is covered by flowing water from flowing streams. The longer the time during which the wetland holds flood water, the greater its significance in performing this subfunction. H - Wetland is flooded 'long to very long' periods; M - Wetland is flooded 'brief' periods; L - Wetland is flooded 'very brief' periods or not at all. Floodwater Storage Proposed restoration or Floodplain enhancement site does boundaries not store flood waters for sufficient time to alleviate downstream flooding. Wetland Size (B2) Storage Even if a wetland is relatively narrow along a stream, if it is of considerable length and H - Wetland is >.54% of total HU area; M - Wetland is % of HU area; L - Wetland is <.05% of HU Floodwater Storage thus large size, it can store area. significant amounts of water. Watershed Position (B3) Width of Wetland Subject to Flooding (B4) Storage Storage Wetlands along large streams further downstream in a watershed are the most significant in receiving and holding in-stream flood waters. The wider a wetland is along a stream, the more area is available over which flood waters can spread. H - > third order stream; M - second or third order stream; L - intermittent or first order stream. H - > 100 ft.; M ft.; L < 50 ft. Floodwater Storage Floodwater Storage Proposed restoration or enhancement site does not contain sufficient wetland area to store peak flood water. Wetland size Proposed restoration or Wetland location enhancement site does not store flood waters for sufficient time to alleviate downstream flooding. Proposed restoration or Wetland size enhancement site does not store flood waters for sufficient time to alleviate downstream flooding. IIC. Shoreline Stabilization Function Proximity to Water Body (C1) Erosion If a wetland occupies a shoreline, the larger the stream or the greater the fetch of open water, the more erosive force is likely to be present. H - < 50 ft. from shoreline of Erosion Control a second or higher order stream or of an estuary or lake shoreline; M - < 50 ft. from an estuary shoreline; L - >/= 50 ft. from any stream or > 300 ft. from an estuary shoreline. Proposed restoration or enhancement site is not located on a shoreline and cannot reduce the energy of water movement in the watershed. Wetland location and classification Length of Wetland Border Exposed to Open Water (C2) Erosion The longer the length of shoreline that the wetland occupies, the more significant is this function in relation to other wetland functions. H - > 500 ft. of wetland perimeter borders open water; M ft. of perimeter borders open water; L - < 100 ft. of perimeter borders open water. Erosion Control Proposed restoration or enhancement site does not border on open water. Wetland location and classification Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

37 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts III. HABITAT IIIA. Endangered Species/Significant Natural Areas Watershed Land Use (C3) Exceptional Habitat Functions (A) Erosion Habitat Function The flow rate and erosive force of a stream are increased by more rapid runoff of storm water from cleared and developed land than from forested land. H - >/= 1% developed or > 20% developed + agriculture; L - < 1% developed or < 20% developed + agriculture. Erosion Control If threatened or H - Presence of threatened Protected Species and endangered species on either federal or state lists or endangered species on either federal or state lists Habitats are verified as present or if or area is identified as the area is identified as exemplary or unique natural ecosystem or exemplary or unique natural ecosystem or special wildlife habitat. special wildlife habitat by the State Natural Heritage Program, the wetland as a whole is rated as having Exceptional functional significance. Proposed restoration or enhancement site is not located near developed or agricultural land. Proposed restoration or enhancement site contains the potential presence of threatened or endangered species, exemplary or unique natural ecosystem. or special wildlife habitat. Wetland location and classification Federal and State lists of threatened and endangered species; NC Natural Heritage database Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

38 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts IIIB. Terrestrial Wildlife Habitat Internal Habitat (B1a) Habitat Function For interior dwelling species, as opposed to 'edge' species, the larger the area of unbroken habitat the better. H - > 74 acres; M acres; L - No interior habitat. Habitat Function Proposed restoration or Interior habitat is enhancement site limited calculated as the or no interior habitat. area remaining after the total size of the habitat complex is reduced inward 100 meters from its boundaries to compensate for edge effects. Association with surface water (B1b) Habitat Function Availability of surface water is important to many species and limiting to some. Even if species live elsewhere and visit the wetland to drink, the presence of water results in the area being more heavily used and having high habitat significance. H - Adjacent to permanent surface water; M - Adjacent to intermittent streams; L - Not adjacent to surface water. Habitat Function Proposed restoration or enhancement site is not adjacent to permanent surface water or intermittent stream. Wetland location Internal Heterogeneity of Habitat Complex (B1c) Habitat Function Areas with higher internal H - > 8 vegetation types Habitat Function heterogeneity generally within complex; M provide suitable habitat for vegetation types within more species and often complex; L vegetation better habitat for individual types within entire complex. species due to greater food sources, nesting sites and cover. Internal heterogeneity is measured by the number of vegetation types present in the habitat complex. Proposed restoration or enhancement site does not provide sufficient internal heterogeneity. Vegetation type Wetland Type (B1d) Habitat Function 1d. The wetland type breakdown is based on analysis of field data for food and cover values typical of different wetland environments and on available literature on the habitat value of different wetland types. H - Bottomland hardwood, freshwater marsh, hardwood flat, swamp forest; M - Headwater swamp, pocosin, pine flat, maritime forest; L - Pine plantation, altered site. Habitat Function Proposed restoration or enhancement site provides relatively little natural habitat value. Wetland type Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

39 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Landscape Habitat, Wetland Juxtaposition (B2a) Habitat Function Compatible adjacent habitats provide animals access to additional food and cover, safer dispersal into other areas, and refuge from temporarily adverse in the wetland. H - > 50% of wetland Habitat Connectivity bordered by other wetlands; M - < 50% of wetland bordered by other wetlands; L - Isolated from other wetlands. Proposed restoration or Wetland and enhancement site does vegetative cover not provide habitat type. through connections with a wetland complex. Landscape Habitat, Surrounding Habitat (B2b) Habitat Function Same. H - > 50% of land cover w/in Habitat Connectivity 1/2 mile composed of natural vegetation; M - of land cover w/in 1/2 mile buffer composed of combination of natural vegetation, pine plantation, and agriculture; L - > 20% of land w/in 1/2 mile developed or < 10% natural vegetation. Proposed restoration or enhancement site does not have compatible habitat within 1/2 mile. Wetland and vegetative cover type. Movement System Value, Corridor Value (B3a) Movement System Value, Wetland Island Function (B3b) Habitat Function Habitat Function A wildlife corridor is a potential movement pathway through areas of unsuitable habitat such as agricultural or developed land. The corridor can include natural upland vegetation as well as wetland. Non-continuous islands of habitat can also provide movement pathways for wildlife, provided that these islands are of sufficient size and within reasonable travel distance of one another. H - Corridor > 600 ft. wide connected to contiguous natural vegetation; M - Corridor < 600 ft. wide connected to contiguous natural vegetation; L - Isolated from other natural vegetation. Wildlife Movement H - Isolated wetland > 5 Wildlife Movement acres in size w/in 1/2 mile of the same; M - Isolated wetland > 5 acres in size w/in 1/2 mile of the same; L - Wetland < 1 acre or > 1/2 mile from nearest wetland. Proposed restoration or enhancement site is isolated from other wetlands or contiguous natural vegetation. Proposed restoration or enhancement site is isolated from other wetlands or contiguous natural vegetation. Wetland and vegetative cover type. Wetland and vegetative cover type. Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

40 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts IIIC. Aquatic Life Habitat Anadromous Fish (C1) Aquatic Habitat Function Wetlands along streams H - Adjacent to a river or Habitat Function harboring anadromous fish tributary of a river harboring can provide breeding anadromous fish; annual habitat for these important flooding; not channelized; M species. Anadromous species often move far up - Adjacent to a river or tributary of a river harboring tributary streams to breed. anadromous fish; stream is Floodwater must enter the channelized; L - Not wetland, however, to provide access and adjacent to a river or tributary of a river harboring habitat, and channelization anadromous fish. inhibits this process. Streams that are not channelized, diked, or impounded or otherwise artificially altered are assumed to flood annually. Proposed restoration or enhancement site is not adjacent to a river or tributary of a river harboring anadromous fish. Aquatic species inventories; stream types and geometry Other Fish Species (C2) Aquatic Habitat Function Many stream dwelling fish H - Adjacent to > third order Habitat Function species utilize flooded stream w? annual flooding; wetlands for food, cover, M - Adjacent to a first to and breeding. The larger third order stream w? the stream, the more annual flooding or a significant is this function channelized stream of > due to the greater third order; L - Not adjacent numbers of fish and longer to a stream or stream has periods of flooding. infrequent or nonexistent flooding. Proposed restoration or enhancement site is not adjacent to a stream or stream has infrequent or nonexistent flooding. Aquatic species inventories; stream types and geometry Amphibians and Vertebrates, Wetland Type (C3a) Aquatic Habitat Function Best habitat for amphibians and aquatic invertebrates exists in areas that provide water for egg-laying and larval development yet exclude predatory fish. This occurs in wetlands where isolated vernal pools persist long enough to allow larval development to maturity. Optimum habitat must also include adjacent nonaquatic areas for adult stages. H - Bottomland hardwood, swamp forest, headwater swamp, freshwater marsh; M - Hardwood flat, pocosin, maritime forest; L - Pine flat, pine plantation, altered site. Habitat Function Proposed restoration or Wetland type, enhancement site does vegetative cover, not provide water for egglaying and larval inventories aquatic species development for amphibians and aquatic invertebrates. Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

41 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Amphibians and Vertebrates, Surrounding Habitat (C3b) Aquatic Habitat Function Same H - > 50% of land cover w/in Habitat Function 1/2 mile composed of natural vegetation; M - of land cover w/in 1/2 mile buffer composed of combination of natural vegetation, pine plantation, and agriculture; L - > 20% of land w/in 1/2 mile developed or < 10% natural vegetation. Proposed restoration or enhancement site is not adjacent to non-aquatic areas for adult stages of amphibians and aquatic invertebrates. Wetland type, percent vegetative cover by type Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

42 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts IV. POTENTIAL Landscape Character (IVA) Wetland Extent and Management Wetland Risk Rarity - Percent RISK OF Wetlands (A1a) WETLAND LOSS Wetland extent and rarity H - < 20%; M %; L - measures how common > 50%. wetlands are in the landscape. The higher the proportion of a watershed's land area that is occupied by wetlands, the less vital to the watershed's integrity is one particular wetland. Values are based on conditions in the NC coastal area, where wetlands often comprise 50% or more of the land area. Values would be different for other landscapes with fewer wetlands. Proposed restoration or Percent land use enhancement site in a cover by category HU with wetland area > 20%. Restoration or enhancement of wetland function, particularly in areas where the percent of HU is < 20%. Wetland Extent and Rarity - Percent Wetlands (A1b) Management This is a rating of this type H - < 10%; M %; L - of wetland in the larger > 25%. landscape. In terms of its contributions to landscape diversity, the rarer the wetland type, the greater is its significance. Wetland Risk Proposed restoration or enhancement site is Percent land use cover by category Land Use in Hydrographic Unit, Percent of Land in Agricultural Use (A2a) Management Agricultural land is a H - > 40%; M %; L - significant source of < 10%. nonpoint source pollution. The more agricultural land in the landscape, the more significant are the wetlands in removing pollutants before they enter surface waters. Wetland Extent Proposed restoration or enhancement site is located in agricultural areas. Percent land use cover by category Land Use in Management Hydrographic Unit, Percent of Land in Pine Plantations (A2b) Pine plantations are the most common form of intensive forest management. During the harvest and the regeneration stages of the management cycle, they can be significant sources of nonpoint source pollution. H - > 30%; M %; L - < 10%. Wetland Extent Proposed restoration or enhancement site is located in areas containing extensive pine plantations. Percent land use cover by category Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

43 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Watershed Water Quality Characteristics (IVB) Land Use in Hydrographic Unit, Percent of Land in Urban/Developed Use (A2c) Classification of Major Water Body in Watershed (B1) Use Support of Water Bodies in Watershed (B2) Management Management Management Land development increases surface runoff, increases pollutant loadings, and destroys wildlife habitat. As development increases, all the functions of remaining wetlands become more significant. Since this is the most intensive land use with the most adverse impacts, only a small proportion of the landscape needs to be developed to give wetlands a High rating Maintaining the quality of water bodies with high water quality classification is an important consideration. Water bodies that are subject to high nutrient concentrations or have been identified as impaired where uses can be restored, prevention of pollutant additions are significant to maintaining wetland functions. H - >1%; M %; L - < 0.1%. H - SA, ORW, HQW, WS-I, WS-II, NSW, URW; M - B, WS-III, SB; L - C, CS. Wetland Extent Water Quality Use support designations indicate water quality impairment in relation to use classification. The H - > 25% of stream miles or water body area in watershed less than fully supporting; M % of Water Quality more impaired waters exist stream miles or water body in a watershed, the more significant wetland functions in maintaining water quality. area in watershed less than fully supporting; L - < 10% of stream miles or water body area in watershed less than fully supporting. Proposed restoration or enhancement site is located in areas with intensive urban and other development types. Proposed restoration or enhancement site is subject to high nutrient concentrations or has been identified as impaired. Proposed restoration or enhancement site is characterized as to indicate water quality impairment in relation to use classification. Percent land use cover by category Water quality classification, on-site data collection Water quality classification, on-site data collection Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

44 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Replacement Difficulty for Wetland Functions (IVC) Classification of Water Body Receiving Watershed output (B3) Wetland Type (C1) Management Replacement, Revegetation If the water body receiving H - SA, ORW, HQW, WS-I, the output from the WS-II, NSW, URW; M - B, watershed is classified WS-III, SB; L - C, CS. such that prevention of additional pollutant loading is highly significant, then wetlands in the watershed are of greater significance in maintaining water quality. Wetland types in the H - Pocosin, maritime lowest group are relatively forest; M - Bottomland easy to restore. Those in hardwood, swamp forest, the middle group are more headwater swamp, difficult to restore hardwood or pine flat; L - hydrologically, and their Freshwater marsh, pine vegetation takes a long plantation. time to mature. Wetlands in the highest group are very difficult to restore due to the peculiar nature of their hydrology and the unique site requirements of their vegetation. Water Quality Functional Enhancement or Replacement Proposed restoration or Water quality enhancement site classification, on-site receiving the output from data collection the watershed is classified such that prevention of additional pollutant loading is highly significant. Wetlands in the highest Wetland Type group are very difficult to restore due to the peculiar nature of their hydrology and the unique site requirements of their vegetation. Replacement Site Availability (C2) Replacement If degraded wetland of the same type exists in the watershed, it would be relatively simple to restore it to replace this wetland's functions. Restoring a sire that has been completely converted but is otherwise suitable is more difficult, but still possible. If there is no suitable restoration site in the watershed, replacing this wetland's functions is essentially impossible. Potential restoration sites are located and classified by DCM's restoration site mapping which is done in conjunction with mapping existing wetlands. H - No replacement site Functional Enhancement There is no suitable identified in watershed; M - Non-wetland restoration site available in watershed; L - Degraded wetland site of same types identified in watershed. or Replacement restoration site in the watershed, replacing this wetland's functions is essentially impossible. Wetland: Site Availability Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

45 Table 1: Watershed Functions and Subfunctions Identified in NC-CREWS Functions Subfunctions Indicators Objective Explanation Attributes Constraints Explanation Data Req'ts Enhancement Potential of Site (IVD) Enhancement If a wetland has low functional significance because it is degraded due to drainage or other disturbance, it may still have the potential to be restored to higher levels of function to replace functions lost elsewhere. The closer the wetland is to its fully functioning state, i.e., the less it has been disturbed, the more practical is its restoration and the higher is its significance as a potential restoration site. H - Drained or partially drained wetland w/ natural vegetation intact; M - Drained or partially drained and converted to pine plantation or other intensively managed forest type; L - wetland intact but low functional significance. Functional Enhancement or Replacement Proposed restoration or Wetland field enhancement site has a evaluation high potential to replace functions lost elsewhere. Pasquotank River Local Watershed Functional Rehabilitation Model Report DSPro Project #: DSP December 2003 Table 1

46 Decision Support Professionals, Inc. PO Box 3368 Kill Devil Hills, North Carolina (252) Fax: (252)

47 APPENDIX A Pasquotank River Local Watershed Functional Rehabilitation Model - User Guide

48 User Guide for the Pasquotank River Local Watershed Functional Rehabilitation Model 1.0 Background to Local Watershed Restoration Planning The North Carolina Wetlands Restoration Program (NCWRP) is a non-regulatory, statewide program established to promote the restoration, enhancement, creation, and preservation of wetlands, streams, and riparian areas through watershed planning. The NCWRP has targeted the Pasquotank River Local Watershed for a Local Watershed Planning process. The targeted hydrologic units for the Pasquotank River Local Watershed Restoration Plan are , , and , and are located in Pasquotank, Camden, and Gates Counties within the Pasquotank River Basin (including Elizabeth City). Figure 1 shows an overview of the Pasquotank River Local Watershed Planning Area. Figure 1: General Overview of the Pasquotank River Local Watershed Boundary The NCWRP is currently in the process of refocusing Local Watershed Restoration Plan (LWRP) development to reflect ecological enhancement based on watershed functional needs and opportunities. The LWRP identifies all factors contributing to the degradation of watershed functions within subcatchments and provides multiple strategies to address the threats to those functions. The development of the LWRP from this perspective is important for watershed rehabilitation because wetland and riparian restoration projects alone cannot provide the level of functional improvement needed within a watershed. The strategies identified in the LWRP include not only wetlands, stream, and riparian buffer restoration projects, but also strategies that

49 may be initiated through collaboration with other local, state, and federal programs as well as the private sector initiatives to enhance the success of any single strategy. The Pasquotank River Local Watershed Restoration Plan (PRLWRP) utilizes the functional assessment approach to achieve measurable strategies for the improvement and protection of watershed functions including water quality, flood control and wildlife and fisheries habitat. Four key components make up the PRLWRP and include: Characterizing the watershed based on existing conditions Incorporating watershed condition into a computer-based model to view, evaluate and analyze the watershed functions Evaluate subcatchment functions and review potential project locations to determine which ones will provide the most functional improvements Identify appropriate restoration and/or rehabilitation practices and projects, which address stakeholder priorities and provide measurable improvements to watershed function. The Pasquotank River Local Watershed Functional Rehabilitation Model (Model) is an integral part of the Pasquotank River Local Watershed Restoration Plan (PRLWRP). The Model creates a finer degree of resolution to analyze and evaluate watershed condition and restoration/rehabilitation strategies. The Model incorporates data from the Revised Pasquotank River Local Watershed Characterization Report (PRLWCR), the NC Division of Coastal Management North Carolina Coastal Region Evaluation of Wetland Significance (NC-CREWS), and other data into the CommunityViz software framework. The Model was developed in the CommunityViz software framework, which was developed by the Orton Family Foundation and is a commercial, off-the-shelf Geographic Information System (GIS) based planning and decision support application. The software uses the data handling and visualization capabilities of GIS to enhance decision maker insight and create scenario-driven analyses that evaluate the implications and opportunities of alternative strategies for economic development, land-use and transportation planning, facilities management, environmental risk assessment, remediation and protection, energy forecast, water allocation, and resource control. Driven by user-defined algorithms and assumptions, these systems provide high decision quality, focused investigation of issues at hand, and consistent comparison among alternative planning strategies. The Scenario Analysis Tool provides the underlying framework for the powerful alternative-comparison capabilities of CommunityViz. It also provides a rich set of quantitative impact analysis capabilities, offering the functionality of a spatial spreadsheet that can perform numerical computations on geographic data in real time. 2.0 Introduction to the CommunityViz Software Framework The CommunityViz software is an ArcView extension and contains a suite of three modules; Scenario Constructor, SiteBuilder3D, and Policy Simulator. The Pasquotank River Local Watershed Functional Rehabilitation Model was developed specifically utilizing the CommunityViz Scenario Constructor module. Scenario Constructor is the core module of CommunityViz and provides impact analysis capabilities featuring the functionality of a spatial spreadsheet that can perform numerical Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 2

50 computations on geographic data in real time. Scenario Constructor allows users to create maps, charts, and reports showing alternative scenarios based upon information contained within the GIS enterprise system and other assumptions (CommunityViz Course Training Manual). Pricing information for Scenario Constructor Module (stand-alone), along with the three-module suite can be found at or by contacting the sales department at (866) CommunityViz Hardware and Software Requirements The following is a generalized list of hardware requirements and options needed to run CommunityViz; MHz Intel compatible, Pentium II or higher CPU 256 MB RAM High-end graphics card (Minimum 32 MB RAM) supporting OpenGL 400 MB free disk space for installation 2 GB for data 3-button mouse (preferred) Windows NT 4.0 service pack or higher or Windows 2000 The following is a generalized list of software requirements and options needed to use CommunityViz; Application Software ArcView 3.2 ArcView Spatial Analyst 2.0 ArcView 3D Analyst (optional to support TINs for use in SiteBuilder3D) CommunityViz Operating Systems Windows NT (Service Pack 4) Windows Data Requirements for Scenario Constructor Scenario Constructor utilizes typical GIS layers, such as; Roads Rivers Parcels Zoning Imagery User Created data layers Note: Scenario Constructor, like most GIS applications, is data-centric. Thus, as in any GIS application, the usefulness of Scenario Constructor is dependant on the depth and condition of the GIS database. Implementing Scenario Constructor will require certain basic data layers to be present, as well as basic tabular data fields, but you can also create and edit your own GIS data while using Scenario Constructor (CommunityViz Training Manual). Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 3

51 3.0 Components of the Pasquotank River Local Watershed Functional Rehabilitation Model 3.1 CommunityViz Scenario Constructor Framework The Scenario Constructor module of CommunityViz adds a decision framework to ArcView GIS to assist in framing many land use decisions by using basic decision elements, such as determining goals and objectives, defining the problem and potential causes, identifying and evaluating alternative solutions, implementing the best alternative and finally re-evaluating the results. There are two basic users of Scenario Constructor; Scenario Exploration Users, which simply explore decision alternatives, based on existing scenarios, and Scenario Setup Users, who create and/or modify existing scenarios and would need to be more experienced in manipulating ArcView views, themes, and tables along with some familiarity with ArcView Field Calculator or Avenue scripting. A Scenario is a View (like in ArcView) with additional information elements attached that implement a decision framework. A Scenario is made up of fundamental data sets and definitions and formulas, which define the objectives, assumptions, and constraints of a particular decision. There are four key components of CommunityViz Scenario Constructor: indicators, assumptions, constraints, and auto data. These components are defined below and described in more detail in Sections through Indicators are measurable or computed values that represent specific scenario goals. Indicators can be set up into categories, such as infrastructure, landuse, etc. and indicators can be graphed. Indicators are scenario-based computations and are set up in the Scenario View Properties under the View dropdown menu. Assumptions/Variables - are values for the indicators that can be challenged or changed. Assumptions are based on literature and best professional judgment. Assumptions are also found in the View dropdown menu under Scenario View Properties. Constraints Scenario specific set of rules and regulations established due to physical, biological, chemical, legal, or other impediments. Constraints are found under the Theme dropdown menu. Auto Data the core information for the Scenario and apply to automated themes, which are themes that are created for analysis and can be edited or modified. 3.2 Pasquotank River Scenario Framework The Pasquotank River Local Watershed Functional Rehabilitation Model was developed in CommunityViz Scenario Constructor and incorporates GIS data layers for the watershed area (parcels, soils, imagery, etc.), data from the Revised PRLWCR, NC-CREWS data, and other data needed for the decision support model. The Pasquotank River Scenario is a turbo-charged View with additional information elements attached, which allow a user to view, manipulate and analyze potential restoration and/or rehabilitation practices to improve the overall watershed functions within the Pasquotank River Local Watershed Planning Area. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 4

52 3.2.1 Pasquotank River Scenario Indicators The indicators in the Pasquotank River Scenario are total nitrogen, total phosphorous, and sediment and are watershed characteristics that can be measured and monitored. These indicators are measurable components of the watershed functions (water quality, hydrology, and habitat). The indicators can be graphed on bar scales to show potential watershed changes from new projects as a result of implemented restoration and rehabilitation practices. Therefore, the indicators show how a new watershed project could improve the overall functional quality of the watershed. These indicator(s) are organized under specific functional categories, the units to be measured (minimum and maximum values), target values (goals) and target labels. An example of an indicator is Nitrogen Compound. The indicator for Nitrogen Compounds has the description Nitrogen compounds delivered in pounds per acre per year from the proposed restoration or enhancement site to the subcatchment, (Revised Pasquotank River Local Watershed Characterization Plan, 2003). The units are lbs/acre/yr. The minimum value is set at 0 and the maximum is set at 7 as an arbitrary scale from least to most. The target levels are set at 6.1 and the label is Current Baseline. The assignments of these numbers are derived from information contained in the PRLWCR. After the necessary information for each indicator is compiled, each indicator can be graphed to visually show the anticipated results associated with a new project. Each indicator can be charted separately or cumulative indicators can be charted. The chart(s) can be created for the watershed, subcatchment, or a portion of the subcatchment Pasquotank River Scenario Assumptions The assumptions (also known as variables) in the Pasquotank River Scenario are based on watershed objectives and are created through literature, best professional judgment, and stakeholder input. For example, one assumption says that a restoration/rehabilitation practice that reduces sedimentation will result in an increase in water quality. The assumptions in this scenario are all percent reductions for the restoration and rehabilitation practices (revegetation, constructed wetlands, vegetative filter strips, wet detention ponds, and riparian buffers which include shoreline stabilization measures), which are derived from the North Carolina Division of Water Quality (NCDWQ) document for the Tar-Pamlico and Neuse River Nutrient Reduction Goals and the Environmental Protection Agency (EPA) document, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters. These assumptions require a description, a category, a value, units, and minimum and maximum values, which is similar to the indicators. For example one assumption/variable is Constructed Wetlands Sediments. Its description is percent reduction of sediment by constructed wetlands. Average percentage based on literature reviewed (Table 18 in Revised PRLWCR for removal efficiencies). The value is set at 60% reduction within the range of 0 for the minimum value and 80 for the maximum. Because these assumptions are based on literature, best professional judgment, and stakeholder input, they can be challenged. CommunityViz allows the user to change the assumptions within the minimum and maximum range for enhanced alternative analysis. For example, if the user does not agree that a constructed wetland reduces sediment by 60%, the user can change the assumptions to another reduction percentage within the minimum/maximum range and review the effects of that change on the indicator charts. Changing the assumptions allows the user to compare alternatives. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 5

53 3.2.3 Pasquotank River Scenario Constraints The constraints in the Pasquotank River Scenario are factors (physical, chemical, biological, social, economic, regulatory, etc.) that must be considered when evaluating resources to be managed or for management actions. The constraints also serve as alerts to particular aspects of an area that has low functions according to NC-CREWS. These alerts display the functions that could be improved by a potential project. Constraints require a description, a category, and a formula, which is in the form of If the value of some data is X, then display this constraint violation. The formulas for constraints and auto data can be created using an Edit Wizard, which is provided by CommunityViz Scenario Constructor. Constraints also require the user to determine if the constraint is to be displayed or hidden in the menu, and determines what message is to be displayed. For example, one constraint in the Pasquotank River Scenario is for Runoff Storage. The description says, Display an alert message if Wetland Size (A2) RANK =.3 OR Wetland Size (A2) RANK =.1, which describes the minimum and maximum size of the wetland area. The constraint is recognized and the alert message reads, Proposed restoration or enhancement site does not contain sufficient wetland area to decrease peak floodwater discharge. There are similar constraints for other watershed functions and other minimums and maximums associated with those functions and are based on NC-CREWS data Pasquotank River Scenario Auto Data The auto data in CommunityViz is essentially the core of all information the Model operates from and is utilized in the Pasquotank River Scenario. The auto data are manually entered in the Scenario Theme Properties and only apply to automated themes (themes that are created for analysis). For example, in the Pasquotank River Scenario the automated theme New Watershed Project one of the auto data that is created for that theme is wetland size. Each auto data has a description, a category, a formula, units, and a visibility option. The wetland size auto data has the description, Area of the proposed restoration or enhancement site, under the general category, with the formula [Shape].ReturnArea * #Acres per Sq Meter#, and acres as the units. 4.0 Pasquotank River Scenario Instructions The Pasquotank River Local Watershed Functional Rehabilitation Model (Model) is set up in a step-by-step process that allows the user to evaluate several different alternatives with new potential project sites. The data sets, formulas, and calculations have all been implemented into the Model and the Pasquotank River Scenario has been established in order to allow a user to explore potential restoration and/or rehabilitation practices and visually analyze the functional improvement to the watershed, as well as view alternative practices to help make informed decisions for the watershed. The five restoration and/or rehabilitation practices that can be implemented in the Pasquotank River Scenario include: revegetation, constructed wetlands, vegetative filter strips, wet detention ponds, and riparian buffers. The restoration and/or rehabilitation practices and the average percent reductions associated with the practices are based on literature and best professional judgment utilizing the Tar-Pamlico and Neuse River Nutrient Reduction Goals and the Environmental Protection Agency (EPA) document, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 6

54 Step 1. Determine Wetland Restoration and Management Potential A user may want to explore potential restoration and/or rehabilitation practices for a particular property, or a user may want to review current watershed functions within the whole watershed to determine which areas to target for watershed improvement. In this case, a user can utilize the Screening Map Theme (Figure 2) in the Model as a review of the High, Moderate, and Low functional potential of the entire watershed determined by the 39 NC-CREWS model parameters. When the Screening Map Theme is turned on, a grid layer is displayed with three different management range thresholds set for each site: preservation, enhancement, restoration or replacement. This data layer allows the user to quickly find the particular type of management areas to be targeted. In addition, the user can review other data sets within the model, such as aerial photographs, Division of Coastal Management (DCM) wetlands, natural heritage areas, and Unites States Geological Survey (USGS) blue line streams, which can also be helpful. Figure 2: Screening Map of the Pasquotank Watershed based on 39 NC-CREWS parameter ratings. The different shades of green represent the three different management range thresholds. Step 2. Explore New Watershed Project Once a focus area is chosen, the Screening Map Theme is turned off and then the user selects the New Watershed Project Automated Theme (theme denoted by ** before the name) in ArcView. An automated theme is a theme that can be edited and modified during experimentation. The automated theme New Watershed Project was created so the user can begin exploring potential restoration and/or rehabilitation practices and any functional improvement associated with the proposed practice(s). Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 7

55 Figure 3: New Watershed Project automated theme found within the data layers table of contents. Helpful Hint: Once a potential property has been chosen, it is helpful to consider what type of restoration and/or rehabilitation practice (s) would be appropriate for that property; revegetation, constructed wetland, vegetative filter strip, wet detention pond, and/or riparian buffer. This is helpful because when the user starts the analysis on the potential property, six questions are prompted. The questions are site-specific information (based on NC-CREWS) that the Pasquotank River Scenario may require for calculations. If a question does not pertain to the type of restoration and/or rehabilitation practice (s) of interest, the user can hit cancel and continue without affecting the outcome. The following questions are prompted; 1. The site perimeter is adjacent too: <= 20% agriculture, developed, and pine plantation > 20% agriculture and developed > 20 % agriculture, developed, and pine plantation 2. What percentage of the stream is bordered by agricultural or developed land? < 5% > 25% 5-25% 3. How much of the wetland perimeter borders open water? feet < 100 feet > 500 feet 4. How much of the wetland is bordered by other wetlands? >= 50% < 50% Is isolated 5. Measure the width of the new watershed project (feet). 6. Measure the width of the wildlife corridor (feet). The measuring tool provided in ArcView can aid in answering these questions. In addition, the measurements can be refined as more information is determined for the new watershed project and the property can be re-analyzed in the scenario. The Edit Scenario button on the tool bar is used to draw a potential new watershed project specific to the size and location desired. To draw, the user has the option to selects either a square, circle, or polygon as the shape of the new project. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 8

56 Figure 4: Edit Scenario window displays options for editing automated themes. Step 3. Integrate Stakeholder Issues/Impacts Once the new watershed project is drawn, the user is then presented with a series of questions that will appear as part of the auto data asking for site-specific data that the model requires (as part of NC-CREWS) for various calculations (see above six questions). Once the questions have been answered, the first prompt asks the users to select among a suite of watershed issued based on local concerns as identified by the stakeholders. These issues are primarily related to runoff, flooding, erosion, nutrients, sediments, dissolved solids, and ecosystem. The user must select an issue to address throughout the new watershed project. Once an issue is chosen, the second prompt is a suite of impacts related to that issue that the model will use to run the analysis. Figure 5: User choice prompt boxes for stakeholder issues and impacts. Step 4. Incorporate Restoration and Rehabilitation Practices The third prompt is a suite of recommended Restoration/Rehabilitation Practices (R&R practices). The user selects one or more R&R practice to reduce the effects of those impacts on that watershed. Figure 6: User choice prompt for Restoration/Rehabilitation Practices. The next several prompts are related to other various elements of the auto data that require the user to either visually determine or manually measure site-specific characteristics. All of the prompts are created in the Scenario Theme Properties under Auto Data menu. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 9

57 Figure 7: User choice prompts for various NC-CREWS elements. Step 5. Review Wetland Functions for Replacement or Enhancement After the issue, impact and R&R(s) practices are chosen, the model runs through all of the NC- CREWS indicators (Water Quality, Hydrology, Habitat, Potential Risk of Loss) to generate the auto data and all the constraints and assumptions to rate the chosen site (high, moderate or low) based on its ability to provide those functions/subfunctions. For example, the NC-CREWS Habitat parameter Corridor Value is given a rank of 60 points for the given new watershed project because it has a corridor width of 600 ft. or more and according to NC-CREWS, that width is given a high ranking. The Constraint Check describes which functions are impaired or could be improved based on the points given. Figure 8: Constraint Violation alert box and New Watershed Project attribute box. Step 6. Creating Indicator Charts and Analyzing Alternatives After the user analyzes the auto data and constraints, an indicator chart(s) can be created and analyzed. These charts are created in the CommunityViz dropdown menu, Charts. A display window will appear asking whether or not the user wants to view an existing chart or create a new one. If the user chooses to create a new chart, the Indicator Charting window appears. The top Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 10

58 left side of the window shows the available indicators that have been created for this indicator and a chart can be created by selecting it with one click and clicking on the >> button. This enters all the relevant information under the Chart Information section. New Chart creates a new chart in the scenario. Figure 9: Indicator Charts. CommunityViz allows for changes to the new watershed project on the fly through these indicator charts. For example, the user can select a different issue, impact, restoration/rehabilitation practice, or any of the other user inputs and run the model again (Figure 10). The indicator charts will then adjust accordingly but still show the previous marks to allow the user to compare between the two. Figure 10: Use this button to change any of the New Watershed Project s attributes including the issue, impacts, and restoration/rehabilitation practice. The restoration/rehabilitation practices have the biggest influence on the Indicator Charts because they show what change the restoration/rehabilitation practice made on the chosen impact in the proposed site. Each restoration/rehabilitation practice has specific reduction rate ranges for sediments, phosphorus, and nitrogen compounds, which are set at the average and can be challenged and changed if the rate is not acceptable. Default values are derived from the Tar- Pamlico and Neuse River Nutrient Reduction Goals and the Environmental Protection Agency (EPA) document, Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters. This process can be applied by using the CommunityViz drop down menu, Assumptions. To do this, the user must bring up the list of assumptions under the CommunityViz dropdown menu by clicking on Assumptions. The user must then double-click on the desired assumption to bring up the slider bar. The default value is represented on the bar but can be slid to any value above the minimum and below the maximum. After the desired value is entered, clicking on the lightning bolt changes the indicator chart to represent the change. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 11

59 For example, if one believes that the set percentage for nitrogen reduction by detention ponds is too high, the assumption/variable list can be double-clicked and the slider bar moved to the appropriate value. Clicking on the lightening bolt changes that assumption throughout the scenario s calculations and the indicator charts again display that change. The D button changes the value back to the default value if desired. Figure 11: Assumption slider bar pop-up window. The user at this point has the option to either review another site and compare the reduction percentages with the first site or to continue changing the issues, impacts or restoration/rehabilitation practices for comparative analysis of the selected site to find out which types of practices will provide the most functional improvement. Pasquotank River Local Watershed Functional Rehabilitation Model User Guide December 2003 DSPro Project No. DSP Page 12