Modeling and Evaluating Best Management Practices in Austin, TX Presented by Lauren Schneider Environmental and Water Resources Engineering November 30, 2004

BMP Background Used for storm water managementUsed for storm water management Need for small, on-site systemsNeed for small, on-site systems EffectivenessEffectiveness –Groundwater Recharge –Peak Flow Reduction –Pollution and Sediment Reduction ExamplesExamples –Vegetated Buffer Strips –Porous Pavements –Cisterns CA Stormwater BMP Handbook Federal Highway Administration

Bioretention (Rain Garden) Dr. Moglen, University of Maryland

My Past Research Goal: Determine storms needed to verify a BMP modelGoal: Determine storms needed to verify a BMP model Infiltration trench model based on continuityInfiltration trench model based on continuity Indicators of effectivenessIndicators of effectiveness –R p ~ 50% –E t ~ 75% –R v ~ 70% HoHo HbHb L Trench Box (crushed stone) nlnl Inflow from A c S LbLb W

Goal and Objectives Problem: Effectiveness of implemented BMPs is unknownProblem: Effectiveness of implemented BMPs is unknown Long-Term Goal: Using a verified model, evaluate the effectiveness of current and future BMPs installed in Austin.Long-Term Goal: Using a verified model, evaluate the effectiveness of current and future BMPs installed in Austin. ObjectivesObjectives –Develop and verify a model –Use GIS to determine drainage area characteristics –Develop a process for GIS inputs to model –Determine ineffective BMPs for study

Necessary Data Soil Type (Statsgo)Soil Type (Statsgo) BMP data for Austin (Ellen Wadsworth of the city of AustinBMP data for Austin (Ellen Wadsworth of the city of Austin 10-m DEM (USGS)10-m DEM (USGS) Land Use (USGS)Land Use (USGS)

Austin BMP Data Removal in lbs/yr

Process Terrain ProcessingCreate Subwatersheds

Clip Land Use to Subwatersheds Process Determine Soil Type in Each Subwatershed

Process Calculate Overall CN Per Subwatershed Source for CN: R.H. McCuen, Hydrologic Analysis and Design

Inputs from GIS to Model Drainage AreaDrainage Area

Inputs from GIS to Model Rainfall data for AustinRainfall data for Austin SlopeSlope SCS Curve Number (CN)SCS Curve Number (CN)

Example of Results One BMP (ID 5) was examinedOne BMP (ID 5) was examined Two variables were variedTwo variables were varied –Drainage Area (1.95 to 4.13 acres) –CN (94 to 85) One example: E tOne example: E t

Conclusions and Future Work ConclusionsConclusions –Developed a possible process –Drainage Area and CN are significant –Drainage Area can vary greatly Future WorkFuture Work –Verify the model –Obtain more information about installed BMPs –Use better data for terrain processing –Determine best process for drainage area

Acknowledgements Dr. MaidmentDr. Maidment Ellen WadsworthEllen Wadsworth Christine DartiguenaveChristine Dartiguenave