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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

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

contents
Contents
  • Basic concepts
  • New data layers
  • How web model works
  • Integration with IWQA
  • Training in 2008
basic model concepts
Basic Model Concepts
  • Model is easy to run
  • Always gives an output…
  • Important to understand assumptions
  • and limitations
assumptions
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
limitations
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
long term hydrologic impact assessment lthia
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.
process flowchart

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

slide10

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.

slide12

Raster input

  • Edit raster landuse layer
  • and change scenarios
slide14

Curve Number Basics:

rainfall to runoff ratio for different surfaces

Direct

Runoff

Rainfall

http://www.ecn.purdue.edu/runoff/documentation/scs.htm

slide16

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.

slide17

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

databases provide input
Databases provide input
  • Weather data (30 years of real rainfall)
  • Soil data (SSURGO )
  • Elevation data 10m DEM (for contributing area)
process for web gis tools

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

lthia web site
LTHIA Web site

Choose to click a point, input X and Y, or select a 14 – digit watershed

change land use in the watershed using online digitizing tool
Change Land Use in the Watershed Using Online Digitizing Tool

For Example,Add Low Density Residential, Commercial, and High Density Residential Areas

scenario results page
Scenario Results Page

Present Land Use Data

After Change Land Use Data

Application Buttons forHydrological Model Operation

l thia input page after changing land use
L-THIA Input Page After Changing Land Use

Multiple scenarios – offer multiple development options. User constructs scenario by online digitizing.

l thia result runoff tables
L-THIA Result Runoff Tables

Can display pre-and post calibration and also land-use change scenarios.

long term hydrologic impact assessment lthia1
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
near future calibration module in development
Near Future:Calibration module in development:
  • 15 counties landuse from parcel data
  • Hands-on Training
slide35

The End

Thank You

https://engineering.purdue.edu/~lthia

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