1 Develop/update spreadsheet model for regional loading and trends Michelle Lent, John Oram, and Lester McKee Sources Pathways and Loadings Workgroup May 6 th 2010 Item #3a San Francisco Estuary Institute

2 Background: Version 1 Developed by Davis et al. in 2000 to estimate contaminant loads to Bay and coastal waters Developed by Davis et al. in 2000 to estimate contaminant loads to Bay and coastal waters Simple rainfall/runoff model Simple rainfall/runoff model Loads generation: Loads generation: W =  C j  r j  i  A j j where j = land use categories Item #3a San Francisco Estuary Institute TSS TSS Cadmium Cadmium Chromium Chromium Copper Copper Lead Lead Nickel Nickel Zinc Zinc BOD BOD Loads estimated for: Loads estimated for:

3 Background: Version 1 Spatial extent Spatial extent CalWater HUC8 CalWater HUC8 Spatial resolution Spatial resolution 34 watersheds 34 watersheds Temporal resolution Temporal resolution Long-term average annual scale Long-term average annual scale Item #3a San Francisco Estuary Institute

4 Updates/Refinements Replace 1995 ABAG Land Use data set with ABAG 2005 (unless WG recommends differently) Replace 1995 ABAG Land Use data set with ABAG 2005 (unless WG recommends differently) Increase spatial resolution (finer-scale watersheds) using WLA boundaries and BASMAA nomenclature Increase spatial resolution (finer-scale watersheds) using WLA boundaries and BASMAA nomenclature Increase land use category resolution (e.g. split out transportation land use – pending outcomes of STLS task 4d) Increase land use category resolution (e.g. split out transportation land use – pending outcomes of STLS task 4d) Use spatially averaged rainfall instead of watershed centroid method Use spatially averaged rainfall instead of watershed centroid method Increase temporal resolution to long-term monthly scale Increase temporal resolution to long-term monthly scale Calibrate runoff coefficients Calibrate runoff coefficients Item #3a San Francisco Estuary Institute

5 Spatial Extent Item #3a San Francisco Estuary Institute Vs. Or some other extent…

6 Increase temporal resolution 30-year average monthly PRISM data 30-year average monthly PRISM data 800-meter grid 800-meter grid 100ths of mm rainfall 100ths of mm rainfall Potentially could scale/calibrate runoff coefficients by month to account for antecedent conditions, e.g. using Z4LA data Potentially could scale/calibrate runoff coefficients by month to account for antecedent conditions, e.g. using Z4LA data Item #3a San Francisco Estuary Institute

7 Impacts of increasing spatial and temporal resolution: Item #3a San Francisco Estuary Institute If 10 POC loads calculated per watershed, Annual output: ~3*10 2 Monthly output: ~3*10 3 If 10 POC loads calculated per watershed, Annual output: ~5*10 3 Monthly output: ~5*10 4 Vs. …so will need to aggregate watershed output for reporting ~3*10 Watersheds~5*10 2 Watersheds

8 Landuse-based Runoff Coefficients…some options: Previous version of model (BASMAA, 1996; SCCWRP, 2000) Previous version of model (BASMAA, 1996; SCCWRP, 2000) - Developed specifically for Bay Area (mostly) Rantz, 1971 Rantz, Developed specifically for Bay Area Browne, 1996 Browne, Also split out by slope and soil group Compilation in Park et al., 2009 Compilation in Park et al., 2009 Item #3a San Francisco Estuary Institute

9 Potential pollutants to model (as land- use-specific data are available) Item #3a San Francisco Estuary Institute MRP Category 1: – Suspended Sediments – Total Organic Carbon – Copper – Mercury – PCBs – Nitrate as N? Need to prioritize effort: MRP Category 2: – Selenium – Phosphorous – PBDEs – PAHs – Pyrethroids – OC Pesticides Chlordane DDTs Dieldrin Base model development versus Number of pollutants added

10 Reached consensus? Spatial extent of model Spatial extent of model Desired aggregation of output Desired aggregation of output Recommended runoff coefficients to try Recommended runoff coefficients to try How to divide time/effort between base model development (e.g. calibration) and further model development (e.g. adding in more POCs) How to divide time/effort between base model development (e.g. calibration) and further model development (e.g. adding in more POCs) - Which POCs to include in this phase and which to include in subsequent phases Any other issues? Any other issues? Item #3a San Francisco Estuary Institute

11 RMP 2011 rationale for further support This model supports STLS/MRP management questions by: This model supports STLS/MRP management questions by: Providing regional loads estimates Providing regional loads estimates Testing BMP options Testing BMP options In 2010 the model will: In 2010 the model will: Provide average monthly regional estimates of storm water volume, suspended sediment loads, and other POC loads (as specified by WG) Provide average monthly regional estimates of storm water volume, suspended sediment loads, and other POC loads (as specified by WG) In 2011, with further funding, the model could potentially: In 2011, with further funding, the model could potentially: Provide average monthly regional loads estimates of more POCs Provide average monthly regional loads estimates of more POCs Be further calibrated to runoff, if needed/desired Be further calibrated to runoff, if needed/desired Be updated with local land-use specific EMCs, if available Be updated with local land-use specific EMCs, if available Have BMP testing capabilities developed Have BMP testing capabilities developed Item #3a San Francisco Estuary Institute