Erosion by ephemeral gullies, formed by water during heavy rains, is a significant concern in Oregon and the Pacific Northwest and removes soil rapidly from agricultural fields and disperses it into streams and rivers. Ephemeral gullies not only result in the loss of productive soil, but can also mean a concentrated transfer of farm chemicals into waterways, where they feed algal blooms and contaminate drinking water source areas.  This kind of erosion is not included in conventional soil-loss measures, and as a result, is typically underestimated by many current models.

This study focuses on subwatersheds in Oregon that have experienced substantial wildfire events within the past decade and where impacts on agriculture have included increased runoff and erosion. Methodologies for identifying the quantity and location of sediment delivery using aerial imagery, remote sensing imagery and LiDAR is presented to determine if ephemeral gullies are becoming more prevalent in agricultural landscapes affected by wildfire and/or intentional fire. Runoff from wildfire has been shown to increase water turbidity, nutrient concentrations, and fluxes of organic matter, which have to be treated and lead to concerns for drinking water quality. The combination of spatial imagery is used to determine soil moisture content to identify which soils are at highest risk of becoming hydrophobic, and therefore more susceptible to runoff after wildfire occurs, depressional areas for potential water storage to reduce runoff, flooding, and finally if agricultural landscapes (farmlands and rangelands) exposed to wildfire experience greater erosion than those that are not affected by wildfire.