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Green Stormwater: LID with GIS
The document outlines the use of GIS to evaluate and implement Best Management Practices (BMPs) for managing stormwater and protecting water resources. It describes a proactive and reactive approach to stormwater management, detailing steps for community involvement, site evaluation, and BMP selection based on various environmental factors. The document emphasizes the importance of analyzing data related to soil, topography, and land cover to inform effective BMP placement and stormwater management strategies.
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Green Stormwater: LID with GIS
- 1. Scott M. Kaiser,GISP, CFM GIS Analyst & Environmental Planner
- 2. Introduction • Use GISto evaluate the potential and place stormwater BMPs. • Why use GIS • Free and/or inexpensive, readily available data • Increased efficiency
- 3. What are BMPs? BMP– Best Management Practice Structural and non-structural methods to manage the adverse impacts of developed land Primarily used to protect water resources through pollutant reduction, volume reduction and/or flow attenuation. LID oriented
- 4. What is LID? LID– Low Impact Development Attempting to manage rainfall were it lands - as nature would. Implementing LID with BMPs
- 5. Types of BMPs? Bioinfiltration aka rain gardens Porous roadways Hydrodynamic separation Green roofs Rain barrels Riparian buffers Underground detention with infiltration Open space preservation* Floodplain, riparian and wetland preservation* Reduced impervious or compacted surfaces* *No construction necessary
- 6. Example BMPs Bioinfiltration Porous Surfaces Rain Barrel Green Roof
- 7. Helping Managing Stormwater with GIS Two pronged approach: Proactive Use data to help direct future stormwater management and/or rehabilitation projects. Reactive Typical method Use GIS to guide a response to mitigate an existing problem such as flooding or pollution.
- 8. Analytical Goal Sites with… Good Soils Gentle Slopes Open Space or right-of-way } Infiltration BMPs Moderate to low storm flow Open space or right-of-way Proximity to existing infrastructure } Hydrodynamic Separation Wetlands Greenway Floodplain Parks or Preserves } Preservation/Habitat Rehab
- 9. Data Considerations Topography and slope Structural BMPs, <5% Existing infrastructure Proximity to storm structures Land ownership Public and private opportunities Hydrography Land cover Determine runoff volume and velocities Orthoimagery
- 10. Software ArcGIS Desktop andSpatial Analyst Optional (advanced data development and analysis) Image processing – eCognition or Feature Analyst Modeling - SWMM
- 11. The Process… • The discussion will focus on conceptual BMP placement to help a community or organization fix stormwater problems. • Reactive approach
- 12. The Process… Step 1.Public Involvement Getting the public input Hold a charrette Bring maps to mark-up based on public comment
- 13. The Process… Step 2.Find Open Space Opportunities Parks, preserves, riparian corridors, wetlands, floodplains, and/or conservation easements
- 14. The Process… Step 2.Find Open Space Opportunities
- 15. The Process… Step 3.Determine Potential Public Improvement Projects • Existing improvements projects are excellent opportunities for stormwater BMP retrofits • Consider road reconstruction and property redevelopment
- 16. The Process… Step 3.Determine Potential Public Improvement Projects
- 17. The Process… Step 4.Pick an Area of Interest Narrow list of areas to focus on LID techniques Can be one to many sites
- 18. The Process… Step 4.Pick an Area of Interest
- 19. The Process… Step 5.Delineate Watershed and Catchments for Area of Interest • Several factors to consider: • Start with ArcHydro for DEM based topography • Don’t forget human induced drainage – Storm sewer – Lot and road grading
- 20. The Process… Step 5.Delineate Watershed and Catchments for Area of Interest
- 21. The Process… Step 6.Calculate Slope BMPs are best used on slopes less than 5% Run DEM through Spatial Analyst 10m or 30m DEM LIDAR is becoming a popular
- 22. The Process… Step 6.Calculate Slope
- 23. The Process… Step 7.Evaluate Soils Soil hydrologic groups – A, B, C or D A and B – good infiltration C – ok infiltration D – poor infiltration Determines if soil amendments and underdraining will be necessary
- 24. The Process… Step 7.Evaluate Soils
- 25. The Process… Step 8.Delineate Land Cover • Helps to determine applicable BMP – Commercial/Instructional – green roof – Transportation – porous surfaces or bioinfiltration – Single family homes – rain barrels
- 26. The Process… Step 8.Delineate Land Cover
- 27. The Process… Step 9.Mash it all Together • Evaluate the landscape – Run iterations of intersected data based on slope, soils, land cover, open space, property ownership and improvements projects • Create BMP feature classes • Conceptually sketch BMPs in proposed locations • Prepare to determine BMP volume and pollutant removal
- 28. The Process… Step 9.Mash it all Together
- 29. The Process… Step 10.Determine the Volume Managed and P Removal • Delineate the contributing area to each BMP • Calculate the anticipate volume and/or flows • Estimate the potential nutrient (P) removal
- 30. The Process… Step 10.Determine the Volume Managed and P Removal
- 31. The Process… Step 11.Summarize Findings • Example Contributing Land Cover Contributing Weighte BMP Treatment FF Untreated (sf) C Area (sf) dC FF Volume (cf) (cf) % FF Treated (cf) 251,760 0.95 Bioinfiltration 68,753 0.25 466,006 0.74 14,319 8,244 57.6% 6,074.90 145,493 0.60 681,110 0.95 Porous 39,124 0.60 720,234 0.93 27,939 10,204 36.5% 17,734.70 Sidewalk 1,365,452 0.95 Oversized Pipe 10,585,110 0.60 11,950,562 0.64 318,677 7,530 2.4% 311,146.89 0.45 Total BMP Total FF Volume Total % FF Total FF Volume Treated (cf) Managed Remaining (cf) (cf) 360,935 25,978 7% 334,956
- 32. Lessons Learned • It’sonly GIS • We’re not building bridges • We can get a good conceptual idea for the improvements to stormwater runoff • The only way to truly measure success is over time with metering and sampling.
- 33. Future Projects • VirtualBMP map • BMP database
- 34. Summary • GIS dataand spatial analysis can be effective for BMP mapping • Harness as much readily available data as possible
- 35. Want to KnowMore? Scott Kaiser, GISP, CFM Orchard, Hiltz & McCliment, Inc. ohm-advisors.com scott.kaiser@ohm-advisors.com 734.466.5444