Use of LTHIA to Reduce Nonpoint Source Water Pollution Hands-on Training

1. Use of LTHIA to Reduce Nonpoint Source Water PollutionHands-on Training Bernard A. Engel Tong Zhai Larry Theller Agricultural and Biological Department Purdue University In conjunction with POLIS Center, IUPUI and Indiana Dept. Environmental Management

2. Long Term Hydrologic Impact Assessment (LTHIA) • Calculates the chemistry and volume of runoff water, based only on landuse and soil type. • Changing the landuse in an area will change the typical runoff chemistry. • This uses assumption called “curve-number.” • LTHIA in use for 5 years.

3. https://engineering.purdue.edu/~lthia Processes for Hydrologic Impact Analysis Using Web-GIS Tools Outlet Point Selection Using Aerials, roads, or streams Run Watershed Delineation To get contributing area Watershed Delineation Result Examine maps Reflect Land Use Change Using Online Digitizing Run L-THIA Runoff and NPS Output/Impact Evaluation

5. Landuse 1 Landuse 3 Landuse 3 Soil A Soil B We break soils into 4 hydrologic conditions, which are used to estimate runoff volume. We break landuse into 8 basic types, which are used to estimate chemistry.

6. Curve Number Basics: rainfall to runoff ratio for different surfaces Direct Runoff Rainfall http://www.ecn.purdue.edu/runoff/documentation/scs.htm

7. Averaged mass of NPS contaminant from each landuse

8. LTHIA isolates the flowshed to estimate the runoff, so it calculates runoff for the -shed.

9. Data Issues: Working with 10 meter DEMS means we can not use watersheds larger than 10 digit. So, if the user clicks on the mouth of the Wabash or the Tippecanoe River, they get the first upstream 10 Digit watershed. All contiguous 10 Digit watersheds are supported.

10. Take-Home points DEM is only used to calculate flowshed DEM is not used for not erosion - runoff Runoff is based on surface type – not slope won’t account for frozen ground 30 year average rainfall Chemistry is based on landuse averages

13. Databases provide input • Weather data (30 years of real rainfall) • Soil data (STATSGO or SSURGO ) • Elevation data (for contributing area)

14. Long Term Hydrologic Impact Assessment (LTHIA) • 2007 we added connection to the Indiana Water Quality Atlas • 2007 we added new data: • Landuse based on parcels, • better DEM, • better stream layer

15. https://engineering.purdue.edu/~lthia Processes for Hydrologic Impact Analysis Using Web-GIS Tools Outlet Point Selection Using Aerials, roads, or streams Run Watershed Delineation To get contributing area Watershed Delineation Result Examine maps Reflect Land Use Change Using Online Digitizing Run L-THIA Runoff and NPS Output/Impact Evaluation

16. LTHIA Web site

18. Watershed Delineation and Result Page

19. Watershed Delineation and Result Page

21. Results Display

22. Change Land Use in the Watershed Using Online Digitizing Tool For Example,Add Low Density Residential, Commercial, and High Density Residential Areas

23. L-THIA Input Page After Changing Land Use Multiple scenarios – offer multiple development options. User constructs scenario by online digitizing.

24. Scenario Results Page Present Land Use Data After Change Land Use Data Application Buttons forHydrological Model Operation

25. L-THIA Result Runoff Tables Can display pre-and post calibration and also land-use change scenarios.

26. Comparison Chart for Runoff and Land Use to Evaluate the Land Use Change Impact on Hydrology

27. NPS Pollutant Loading Chart

28. Print and Download Page

29. IWQA GIS Interactive Button to Delineate Watershed Select Outlet Point Coordinate is passed to LTHIA

30. Near Future:L-THIA Input Data PreparationCalibration module in development: • Next 12 months • 15 counties Landuse from parcels • Calibration with IWQA data • Hands-on Training

31. Calibration Display Available IWQA Calibration data points in the regional watershed. User may OK using curve numbers calibrated for watershed.

32. User will be able to identify (query) the IWQA data locations used for calibration.

33. L-THIA Input Data PreparationCalibration module in development: Calibration data will be used behind the scenes to construct modified curve numbers. These modified curves will more closely match the observed results from the IWQA than the published curve numbers.

34. The End Thank You https://engineering.purdue.edu/~lthia