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Abstract
Digital elevation models (DEMs) vary in resolution and accuracy by the production method. DEMs with different resolutions and accuracies can generate varied topographic and hydrological features, which can in turn affect predictions by soil erosion models, such as the WEPP (Water Erosion Prediction Project) model. This study investigates the effects of DEMs on deriving topographic and hydrological attributes, and on predicting watershed erosion using WEPP v2006.5. Six DEMs at three resolutions from three sources were prepared for two small forested watersheds located in northern Idaho, USA. These DEMs were used to calculate topographic and hydrological parameters that served as inputs to WEPP. The model results of sediment yields and runoffs were compared with field observations. For both watersheds, DEMs with different resolutions and sources generated varied watershed shapes and structures, which in turn led to different extracted hill slope and channel lengths and gradients, and produced substantially different erosion predictions by WEPP.
Acknowledgements
We thank Dr William J. Elliot for his valuable advices and suggestions in applying the WEPP model; Shuhui Dun for her technical assistance in running WEPP; Dr Erin Brooks and Bill Dansart for providing us the field‐observed runoff and sediment yield data; and Sue Miller, Dr Andy Hudak, and Jeff Evans for their help in processing the GPS and LIDAR data.