Introducing Web-Based Decision Tools for Environmental Watershed Management

Bernie Engel and Roxanne MitchellAgricultural & Biological EngineeringPurdue Universityengelb@purdue.edu765.494.1198

Outline

L-THIA (Long-Term Hydrologic Impact Assessment)SEDSPEC (peak rates of runoff and erosion and runoff structures)

Long-Term Hydrological Impact Assessment

(L-THIA)

40% 10%

50%Natural Cover

15%

55%30%

75-100% Impervious

35%

30%

35% 35-50% Impervious

Land Use Decisions Affect Runoff, Recharge, and Water Quality

Most communities respond to this with a mix of reactive and proactive strategies, including planning

L-THIABased on the rainfall – land cover – runoff analysis

method already used in many communities

Input: Land Use Pattern(s) + Soils Pattern

Process: Daily Runoff and Pollutant Loading Calculations (30 years)

Output: Average Annual Runoff and NPS loads for Specific Land Use Patterns

A little history….

Northeast Ohio, 1992: “Our wetlands are failing”

Local Planners: Need model to assess impact of land use change on hydrology.

Reality: Available models were data intensive and complex – and getting more so.

The Aim: To develop a user-friendly model using basic available data for land use and soils, in response to the needs of planners and local environmental groups.

L-THIA

Originally a simple spreadsheet program

Now a simple web tool

GIS extension version also available

• L-THIA Web

http://www.ecn.purdue.edu/runoff/lthianew

So how do you do it?

Run L-THIA from Text Input form

• State• County

•Land use and hydrologic soil group selection

•Area input

•Click Next

Tables and charts for interpretation

How is L-THIA Used?Near Columbus, OH – significance of urbanization on runoff and water qualityTriangle Park, NC – comprehensive land use planNASA KSC, FL – impacts of historical land use changeNortheast OH – land use planning policy assessment; wetland protectionIndianapolis, IN – historical impactsKokomo, IN – TMDL development

SEDSPEC Introduction

SedSpec assists in analyzing runoff and erosion problemsProvides information about runoff and erosion control structuresProvides peak runoff estimation using

Rational methodTR55

What you can do using SEDSPECPeak Runoff EstimationPreliminary erosion control structures design and selection

Channels (Grass Lined, Riprap Lined, Concrete Lined, Open) Culvert Sediment Basin Level Terraces Storm Water Detention Basin Runoff Diversion Low Water Crossing

Where you start

pasture.ecn.purdue.edu/~sedspec pasture.ecn.purdue.edu/~watergen

Summary

L-THIASEDSPEC

http://www.ecn.purdue.edu/runoff/lthianewhttp://pasture.ecn.purdue.edu/~sedspec