APPLICATION OF LOW ALTITUDE PHOTOGRAMMETRY TO THE DETERMINATION OF RANGELAND HYDRAULIC PARAMETERS
The physically based erosion model developed by the Water Erosion Prediction Project (WEPP) of the USDA requires input data that are not routinely measured or estimated in the field. Low altitude photogrammetry data were collected at 12 rangeland locations to measure surface micro-elevations needed to estimate hydraulic geometries of the flow. The photogrammetry contour data were converted to cross-sections, and used to calculate the hydraulic geometries and flowpath density on each cross section. The erosion prediction segment of the WEPP model was optimized with the photogrammetrically derived parameters used as input. The low-altitude photogrammetry makes the measurement of surface hydraulic properties possible on low-relief rangelands resulting in more accurate soil erosion predictions.