Water Balance Component of TRCA s Watershed Planning Studies

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1 Water Balance Component of TRCA s Watershed Planning Studies Glenn Farmer and Sonya Meek, TRCA CMHC On-line Teleconference September 22, 2005 REVIEW and EVALUATE MONITOR and REPORT PLAN WATERSHED PLANNING STEPS IMPLEMENT PHASE 1: SCOPING & CHARACTERIZATION Scoping Characterize the system Set goals, objectives and working targets PHASE 2: ANALYSIS & EVALUATION Develop management alternatives Evaluate management alternatives PARTNER INVOLVEMENT Reference: CVC, GRCA and TRCA PHASE 3: WATERSHED PLAN DEVELOPMENT Select preferred management alternatives Finalize targets Develop implementation and monitoring plans 1

2 Water Balance Objectives CHARACTERIZATION Existing surface and ground water balance Human water use and impacts Extent and locations of SWM ANALYSIS AND EVALUATION Assess impact of future land use scenarios on water balance Assess changes in ground water levels, baseflow, instream flow/quality, temp. Assess effectiveness of SWM/retrofits WATERSHED PLAN PRODUCTS Preferred management strategy Model land use policies/criteria (recharge, discharge areas) Water conservation targets SWM criteria (infiltration, flood, erosion, water quality, baseflow, temperature) SW retrofit priority areas Screening process for applicability of SWM/GWM technologies Low flow strategy Climate change adaptive management guidelines. Future Scenarios Rouge River Watershed 2

3 Need to development of a formal TRCA water balance policy and subsequent guideline document which will provide jurisdiction-wide groundwater recharge targets and criteria as well as acceptable methodologies and tools to be used to carry out impact assessments, evaluate alternatives and determine appropriate mitigation strategies to address impacts relating to groundwater recharge Policy and interim guideline document is currently underway and expected to be completed in 2005 early 2006 Initial approach utilizes existing information extracted from recent studies including the City of Toronto Wet Weather Flow Master Plan HSP-F model output, HSP-F modelling being carried out as part of several TRCA watershed studies and existing WABAS water budget modelling available for several watersheds outside the 416/905 watershed areas 3

4 (Continued) Annual groundwater recharge mapping utilized with proposed uses in an overlay approach to determine infiltration deficits associated with changes in land use Screening of alternatives and siting and design of best management practices to address infiltration would be based on traditional desktop methods Initial guideline document will form an interim step given the limitations in current information and technologies including data management and updating of base conditions to reflect more detail, potential hydrogeological constraints and lack of direct link to groundwater modelling (eg., output format etc.) HSP-F model is complex, requiring a significant amount of input data and would be difficult to gain support for wide-spread use by development consultants as a design and management tool Annual Infiltration Deficit Map from HSP-F Output - Humber Watershed TRCA Jurisdiction-Wide Water Balance Initiative (Continued) Goal is to integrate the existing WABAS water budget model into GIS to create an Arc-WABAS model GIS-based tool would be utilized to create a TRCA jurisdictionwide surface water budget model. Benefits would include: -Use of ArcHydro database structure and ability to utilize future datasets under development through the Ministry of Natural Resource s (MNR) Water Resources Information Program (WRIP s) - Ability to create a coupled interface with the Modflow groundwater model which will permit the ability to fully assess surface-groundwater interactions and quantify impacts associated with changes in land use etc. - Will be designed with consideration for future expansion to create a complete hydrologic modelling package with the ability to carry out single event and continuous hydrologic modelling (eg., Qualhymo, user defined time step etc.), water quality analysis as well as shear stress - Ability to be used anywhere given that it is not specific to the TRCA jurisdiction - Will be designed with consideration for use by development consultants in order to ensure consistent modelling approach and ability to integrate new/updated information Groundwater Infiltration from WABAS Model Output - Duffins Watershed 4

5 TRCA Water Balance Policy and Guideline Development (Continued) Funding for the initial phases of Arc-WABAS tool development and preparation of a TRCA jurisdiction-wide surface water budget model is proposed through initiatives such as the Provincial Drinking Water Source Protection Plan Initial schedule of completion for Arc-WABAS is proposed by March 2007 but may vary depending on available funding and/or resources Alternative funding and/or partnerships are also being pursued and would be welcome in order to accelerate the completion of this initiative (eg., Great Lakes Sustainability Fund GLSF, MNR, MOE, CMHC etc.) 5