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William J. Elliot
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Effects of DEM resolution on forest hydrologic and erosion prediction using WEPP

Zhang, J.X.; Wu, J.Q.; Elliot, W.J.; Dun, S.; Chang, K. 2006. Effects of DEM resolution on forest hydrologic and erosion prediction using WEPP. Written for presentation at the 2006 ASABE Annual International Meeting. Sponsored by ASABE, Portland Convention Center, Portland, OR. 9 - 12 July 2006. ASABE Paper No. 062179. American Society of Agricultural and Biological Engineers.

Keywords: forest watershed, water erosion modeling, WEPP, GIS, DEM, LiDAR

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Abstract: The recent modification of WEPP (Water Erosion Prediction Project) has improved the original model.s applicability to hydrology and erosion modeling in forest watersheds. To generate reliable topographic and hydrologic inputs for the WEPP model, carefully selecting Digital Elevation Models (DEMs) with appropriate resolution and accuracy is essential because topography is a major factor controlling water erosion. LIght Detection and Ranging (LiDAR), a new remote sensing technology, provides an alternative for generating fine and high-quality DEMs. This study applies WEPP (v2006.201) for hydrological and erosion simulation under forest conditions and evaluates the effects of DEM resolution and accuracy on watershed hydrology and water erosion prediction at a watershed scale. Stream flow and total suspended solids (TSS) in two small forest watersheds located in northern Idaho were collected and processed. A total of six DEMs from three sources (NED, SRTM, and LiDAR) at three resolutions (30 m, 10 m, and 4 m) were obtained and used to calculate topographic parameters as inputs to the WEPP model. WEPP-simulated hydrologic and erosion results using the six DEMs were compared with the field-observed data. For both study watersheds, DEMs with different resolutions and sources generated varied topographic and hydrologic attributes, which in turn led to significantly different erosion predictions by WEPP.

Moscow FSL publication no. 2006k