Agren Projects

Estimating Soil Loss with RUSLE2 & LiDAR

The Challenge:

The Revised Universal Soil Loss Equation (RUSLE2) is widely used by conservation planners to predict sheet and rill erosion resulting from rainfall. The calculation provides the basis for soil and water conservation practice planning throughout Iowa and much of the nation.

Slope length and slope steepness are two important factors in the scientific model. However, measuring length and steepness of every slope in the field is time-prohibitive and rarely done. It's typical for conservation planners to use averages (book values) for determining both of these inputs to the calculation. But, these average values are generalizations and likely do not reflect actual field conditions in a specific location.

Agren's Solution:

To address these issues, we are cooperating with the USDA National Soil Tilth Laboratory and the Iowa Department of Agriculture and Land Stewardship - Division of Soil Conservation to develop an on-line, GIS-based RUSLE2 calculator. Incorporating newly available, high-resolution elevation data with Geographic Information System (GIS) technology will greatly increase the speed and accuracy of the RUSLE2 model.

The new software will measure slope length and steepness from high-resolution Digital Elevation Models (DEMs) created from LiDAR (Light Detection And Ranging) remote sensing data. Several Iowa agencies partnered to acquire statewide LiDAR coverage in 2006.

As this project began, we convened an expert panel to identify and evaluate existing methods for calculating slope length and steepness from high resolution DEMs. We also are working with different stakeholders from across Iowa to better understand their needs and preferences for using the software and to develop evaluation criteria for the final web-based product.

Currently, the project team is working to evaluate these methodologies and develop a prototype application. Agren is coordinating research and work among several partners including Dr. Daniel Yoder, University of Tennessee; Dr. Chris Renschler, University at Buffalo; Dr. Seth Dabney, USDA National Sedimentation Laboratory; Dave Lightle, USDA Natural Resources Conservation Service; and Marcus Tooze, GIS Workshop. Agren plans to test the application with conservation planners in four Iowa watersheds in early 2010.