Functional Uplift Based Stream Assessment & Restoration Design

Transcription

1 Functional Uplift Based Stream Assessment & Restoration Design Darcy K.L. Turner Senior Environmental Scientist, Biohabitats, Inc. Christopher A. Streb, PE Ecological Engineer, Biohabitats, Inc. Peter I. May, PhD - Senior Ecologist, Biohabitats, Inc. (pmay@biohabitats.com)

2 Stream Assessment & Restoration Design (Urban and Suburban Watersheds) Touch Points: Despite all the challenges, we are trending in the right direction restoring functional processes and improving the ecosystems along our stream corridors kudos to practitioners, agencies and academia Functional Lift + Ecological Uplift = Functional Uplift Upstream hydrology can limit wq and biological lift Case Studies of 2 floodplain reconnection projects - highlight issues with functional assessment structural condition parameters, design challenges, predicted and measured outcomes How Can We Maximize Functional Uplift?

3 Challenges of Stream Restoration in Urban and Suburban Watersheds Tributary to Rock Creek Washington, DC Flashy hydrology Severely impaired biology and water quality Pre-Restoration: 10 ft channel incision Post-Restoration: connection with riparian zone Degradation and entrenched channels requiring fill to attain floodplain reconnection to limit forest impacts and given built environment? Property ownership Built environment/infrastructure

4 Challenges of Stream Restoration in Urban and Suburban Watersheds Biggest Challenge: Hydrology is often a given so reach impacts from upstream sources persist coupled with limitations by reach specific constraints making improvements to biology and water quality are difficult

5 Functional Value Progression of Stream Restoration Next? Integrated Stream and Floodplain Techniques Natural Channel Design Conveyance/Concrete Channels Pipe Bury Headwater Streams Rip-Rap, Gabion, Bank and Bed Treatments Time

6 Functional Value Drivers of Stream Restoration Next? Stream Restoration for Bay TMDLs/NPDES Credits Aquatic Habitat Enhancement Water Quality Improvements Improved Channel Form Conveyance of Flows Protection/Promotion of Built Environment Time

7 Challenges Encountered During Design and Permitting Site Constraints & Watershed Hydrology Assessing Stream and Stream Valley Functions given funds, timeframes, etc. Gaining Buy-in on New Innovative Approaches Predicting Outcomes Demonstrating/Measuring Ecological or Functional Lift

8 Functional Uplift Based Stream Assessment & Restoration Design? Ecological Uplift and Functional Lift = Functional Uplift #1 - strives to further compliment more form based approaches (conveyance, stability and/or dynamic equilibrium based natural channel design) with an increasing emphasis on function #2 - predictably and successfully demonstrates measurable improvement to stream and stream valley processes #3 pairs whole systems thinking - Ecological Uplift with a parameter specific process based evaluation - Functional Lift

9 Parameters that relate to structural conditions of streams are largely based on natural channel design assessment bankfull channel dimensions overview.jpg

10 CASE STUDIES Towson Run Tributary Assessment Metrics & Predicted Benefits of Functional Uplift Carriage Hills Measured Benefits of Functional Uplift from Design

11 A WATERSHED MOMENT Walter and Merritts 2008 Science Craig et al 2008 Frontiers in Ecology

12 Floodplain Reconnection Approach incised groundwater

13 Floodplain Reconnection Approach Riffle Grade Control Floodplain Elevation Incised Channel Bottom

14 Towson Run Tributary Application of Functional Assessment Metrics & Predicted Benefits of Functional Uplift Watershed: Jones Falls, Patapsco River Physiographic Province: Northern Piedmont Plateau Drainage Area: 444 acres Project Area: 15 acres, 4,000 linear feet of stream Description Area Percentage (acres) Institutional % Low Density Residential 3.9 1% Medium Density Residential % High Density Residential % Commercial % Woods % TOTAL AREA %

15 Towson Run Tributary Desired Outcomes Assessment Metrics & Predicts of Functional Uplift Increase Canopy Recharge Groundwater Extend Base Flows Slow Flow/Velocity Wetland Hydrology Increase Contact with Benthos Increase and Retain Carbon Inputs

16 Towson Run Tributary Client Project Goals Assessment Metrics & Predicts of Functional Uplift establish long-term, stable channel geometry reduce sediment yield improve water quality capitalize on opportunities for aquatic and riparian habitat enhancement

17 Hydrology transport of water from the watershed to the channel during multiple storm events increase time of concentration improve hydrology of downstream reaches

18 Hydraulics transport of water in the channel, on the floodplain and through sediments Peak Discharges: 10-year cfs (HydroCAD) 2-year cfs (HydroCAD) Discharge during 3.6 inch runoff event - 44 and 74 cfs reduce peak discharges across a range of storms reduce depth increase roughness wetted perimeter shear stress and velocities

19 Discharge (cfs) Hydraulics transport of water in the channel, on the floodplain and through sediments TRIBUTARY TO TOWSON RUN, CLOISTERS, BALTIMORE COUNTY Bankfull Discharge Identification: Comparision of Field Estimates, Hydrologic Model Results, and Regional Regressions Note: Regression lines extend from the minimum to maximum drainage areas used to develop each regression. Color Coding Used for Points and Lines Shown: Orange & Red Lines/Points = Urban Sites Green Lines/Points = Rural Sites Gray & Blue Lines = Mixture Urban/Rural 1000 Bankfull Q Regression Points, Urban (DEPRM, 1999) Bankfull Q Regression Line, Urban (DEPRM, 1999) Bankfull Q Regression Points, Rural (DEPRM, 1999) Bankfull Q Regression Line (DEPRM, 1999) Bankfull Q Regression, Rural (Cinotto, 2003) Bankfull Q Regression Line (McCandless & Everett, 2002) yr Q Regression (Dillow, 1996) 2-yr Q Regression (Carpenter, 1983) 1.5-yr Q Regression (MDE) 2-yr Q from GISHydro yr Q from GISHydro2000 March 10 event modeled in HydroCAD Trib A2 Trib B M1 M2A M2B M3 M4 M Drainage Area (sq. mi)

20 Hydraulics transport of water in the channel, on the floodplain and through sediments reduce peak discharges across a range of storms reduce depth increased roughness Increase wetted perimeter hydraulic radius reduce shear stress and velocities

21 Hydraulics transport of water in the channel, on the floodplain and through sediments reduce peak discharges across a range of storms reduce depth increase roughness increase wetted perimeter hydraulic radius reduce ear stress and velocities

22 Geomorphology transport of wood and sediment to create diverse bed forms and dynamic equilibrium

23 Physiochemical/water quality - temperature and oxygen regulation; processing of organic material and nutrients Towson University is collecting existing conditions grab samples for analysis Benthic macroinvertebrates and fisheries Temperature loggers with flow monitoring

24 Biology biodiversity and the life histories of aquatic and riparian life increased groundwater elevations maintenance of baseflow Velocity/depth diversity Assessment Metric/Criteria Segment 1 Segment 2 Segment 3 Segment 4 Segment 5 Segment 6 Instream Habitat (0-20) 10 Marginal 10 Marginal Marginal 10 Marginal Epifaunal Substrate (0-20) Marginal 10 Marginal Velocity/Depth Diversity (0-20) 11 9 Marginal Marginal 12 Pool/Glide/Eddy Quality (0-20) & Extent (m) 11 10m 12 25m 12 15m 11 8m 10 Marginal 15m 13 25m Riffle/Run Quality (0-20) & Extent (m) 14 15m 10 Marginal 10m 11 8m 10 Marginal 6m 8 Marginal 15m 11 10m Embeddedness 45% 70% 40% 45% 65% 60% (%) Shading (%) 80% 60% 70% 80% 80% 80% Total Score Velocity (ft/s) Depth (ft) Classification > 0.98 > 1.64 Fast, deep > 0.98 < 1.64 Fast, shallow < 0.98 > 1.64 Slow, deep < 0.98 < 1.64 Slow, shallow

25 Biology biodiversity and the life histories of aquatic and riparian life MBSS Stream Habitat Assessment Existing Conditions Towson Run, Baltimore County, MD MBSS Stream Habitat Assessment Proposed Conditions Towson Run, Baltimore County, MD Velocity/depth diversity 89% slow and shallow 11% fast and shallow, and slow and deep Velocity/depth diversity 67% slow and shallow 29% slow and deep 2% fast and shallow 1% fast and deep

26 Carriage Hills Measured Benefits of Functional Uplift from Design Watershed: Severn River Physiographic Province: Coastal Plain Drainage Area: 11 acres Land Use: Suburban land use, public easement and HOA property Project Area: 11 acres, 425 linear feet of stream (intermittent along downstream) Slope: 10-15%

27 Carriage Hills Measured Benefits of Functional Uplift from Design Goals of Restoration: stable conveyance of storm flows flow attenuation water quality improvements through converting surface to groundwater Construction Cost ~ $340,000 Funded by America Recovery and Reinvestment Act of 2009 (ARRA)

28 Hydraulics transport of water in the channel, on the floodplain and through sediments reduced peak discharges across a range of storms reduced depth increased roughness wetted perimeter hydraulic radius shear stress and velocities Peak Discharges: 100yr = 100 cfs All structures designed to 100yr event Solange Filoso, University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory

29 Hydraulics transport of water in the channel, on the floodplain and through sediments reduced peak discharges across a range of storms Solange Filoso, University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory

30 Water temperature (Centigrade) Physiochemical/water quality - temperature and oxygen regulation; processing of organic material and nutrients reduced instream temperatures 17 control Aug to Sept 2011 restored Solange Filoso, University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory

31 Physiochemical/water quality - temperature and oxygen regulation; processing of organic material and nutrients reduction in phosphorus loads Solange Filoso, University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory

32 Function Based Stream Assessment & Restoration Design How Can We Maximize Functional Uplift? Context: Urban and Suburban Watershed Functional Lift + Ecological Uplift = Functional Uplift?