Spreadsheet Tool for Estimating Pollutant Loads. Models & Decision Support Tools Forum Penn State, Harrisburg, PA August 1, 2011

Transcription

1 Spreadsheet Tool for Estimating Pollutant Loads Models & Decision Support Tools Forum Penn State, Harrisburg, PA August 1, 2011

2 What is STEPL? A customized MS Excel spreadsheet model Simple and easy to use Formulas and default parameter values can be modified by users (optional) with no programming required Calculates nutrient (N, P, and BOD) and sediment loads by land use type and aggregated by watershed Calculates load reductions as a result of implementing BMPs Data driven and highly empirical 2

3 STEPL Users Basic understanding of hydrology, erosion, and pollutant loading processes Knowledge (use and limitation) of environmental data (e.g., land use, agricultural statistics, and BMP efficiencies) Familiarity with MS Excel and Excel Formulas 3

4 STEPL Model User Defined Data Requirements Watershed level data County & weather station Land use distribution Agricultural animal population and manure application information Septic system information Land use specific BMP type and application area Urban Land use types for urban BMPs 4

5 STEPL Model System Defaults These data are derived from user inputs, but can be modified Soil information (based on county) Runoff Curve Numbers (land use/soil group) Urban land use distribution Nutrient concentration in runoff/shallow groundwater Other optional input data Irrigation information Gully & streambank stabilization 5

6 Assumptions and Limitations Water quality calculations are driven by EMCs, so loading accuracy is limited by the variability in EMCs across study area Sediment loads are determined by the USLE Sediment transport and delivery ratios based on regression analysis of drainage area

7 Assumptions and Limitations Coarse Resolution intended as a planning tool Can produce results with a high confidence level Results are only as good as the input data Default data are derived from national, state and county level data The more local data, the more representative the results Designed for use at the HUC 12 level Loads are calculated annually, no daily or seasonal loads

8 New Features in 4.x Ability to specify different ways (by Subwatersheds or Individual Project Area vs. the Entire Watershed) to calculate sediment delivery Calculation of gully and stream bank erosion pollutant loads and BMPs Calculation of groundwater and pollutant output 8

9 Process Sources Groundwater Cropland Urban Runoff Pasture Load before BMP BMP Load after BMP Forest Erosion/ Sedimentation Feedlot Others STEP 1 STEP 2 STEP 3 STEP 4 9

10 STEPL Web Site Link to on-line Data server Link to download setup program to install STEPL program and documents Temporary URL: until moved to EPA server 10

11 STEPL Main Program Run STEPL executable program to create and customize spreadsheet dynamically 11

12 STEPL Spreadsheet Composed of four worksheets 12

13 BMPs Worksheet Each land use type within each watershed can have a separate BMP. Also it can be partial application. 13

14 STEPL BMP Calculator Calculates combined efficiency of a BMP train for a given land use. BMPs in Series BMPs in Parallel 14

15 Urban BMP Worksheet

16 Total Load Worksheet 16

17 Graphs Worksheet 140, , ,000 80,000 60,000 40,000 20,000 0 W1 W2 W3 W4 W5 W6 N Load with BMP (lb/yr) P Load with BMP (lb/yr) BOD Load with BMP (lb/yr) 1,800 1,600 1,400 1,200 1, W1 W2 W3 W4 W5 W6 N Load Reduction (lb/yr) P Load Reduction (lb/yr) BOD Load Reduction (lb/yr) 17

18 Graphs Worksheet Total N Load by Land Uses (with BMP) (lb/yr) 41% 3% 25% 30% Urban Cropland Pastureland Forest Feedlots User Defined Septic

19 Conclusion STEPL is a simple model in terms of data needs, level of effort, etc. Default data is readily available, but accuracy increases with more local data Planning level tool for the HUC12 watershed Key inputs to the model are land cover distribution and BMPs EPA can provide user support and customized versions, if needed 19