The Daily Erosion Project – Adding Channels

Erosion on agricultural lands continues to threaten sustainable production of food and feed. To educate the public on these risks, the Daily Erosion Project, DEP, was launched in the western US Corn Belt in 2014 using weather data from US National Weather Service NEXRAD radar and automated weather stations as well as USDA Soil Survey Geographic (SSURGO) soil properties data, remote sensing methods to gather all slope and management inputs at the field level, including field boundaries, crop rotation, and tillage practices. Our objective in this paper is to develop methods to add channel erosion estimates on agricultural lands to DEP. To estimate channel and hillslope erosion in WEPP Watershed one needs to model more hillslopes, determine average lengths and widths for the hillslopes, and better simulate flow connectivity within the automated DEM enforcement process. Channel imitation can be accomplished by setting critical grid order thresholds similar to the current DEP process for hillslope termination. Channel parameter estimation requires DEMs that have increased flow and elevation accuracy than current DEMs. Lidar return analysis can help define channels that are only partially sampled. The use of a process of limited DEM inversion and filling to remove flow obstructions and effectively clean downstream channel blockages. This results in relatively minor alterations to the DEM and vastly enhances flow connectivity by decreasing basin number by over 75% while limiting flowpath inaccuracy to within one raster cell. Additional flow enhancement criteria could further enhance flow for WEPP Watershed implementations. Additional algorithms are needed to map and parameterize land cover and management in channels as most land cover datasets do not resolve vegetated waterways.