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LTHIA – 2007 -2008 Upgrades and Training

LTHIA – 2007 -2008 Upgrades and 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. Contents. Basic concepts New data layers

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LTHIA – 2007 -2008 Upgrades and Training

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  1. LTHIA – 2007 -2008Upgrades andTraining 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. Contents • Basic concepts • New data layers • How web model works • Integration with IWQA • Training in 2008

  3. Basic Model Concepts • Model is easy to run • Always gives an output… • Important to understand assumptions • and limitations

  4. Assumptions • Water flows across the surface to form flowshed • no storm drains • Water equally spread across landscape • No routing • Average antecedent moisture • soil is not saturated or frozen • Rainfall is evenly spread in local area

  5. Limitations • Accuracy of landuse and soil data • Big limitation • Accuracy of runoff curve number • Hydrological impacts are understated • LID not reflected • Accuracy of published NPS relationship • Lead in runoff based on 1990’s models

  6. 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.

  7. https://engineering.purdue.edu/~lthia Process Flowchart 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

  8. The screens used in the model

  9. 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.

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

  11. Raster input • Edit raster landuse layer • and change scenarios

  12. The software uses raster files of landuse and soil

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

  14. Averaged mass of NPS contaminant from each landuse EMC Table

  15. 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.

  16. Take-Home points DEM is only used to calculate flowshed DEM is not used for erosion – or 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

  17. Databases provide input • Weather data (30 years of real rainfall) • Soil data (SSURGO ) • Elevation data 10m DEM (for contributing area)

  18. https://engineering.purdue.edu/~lthia Process for 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

  19. LTHIA Web site Choose to click a point, input X and Y, or select a 14 – digit watershed

  20. Watershed Delineation and Result Page

  21. Watershed Delineation and Result Page

  22. Results Display

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

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

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

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

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

  28. NPS Pollutant Loading Chart

  29. Print and Download Page

  30. Long Term Hydrologic Impact Assessment (LTHIA) • Added connection to the Indiana Water Quality Atlas • 2001 NLCD landuse statewide • Landuse based on parcels, selected cty • SSURGO soil • better DEM (10 meter) • NHD High –resolution stream layer

  31. Near Future:Calibration module in development: • 15 counties landuse from parcel data • Hands-on Training

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

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