GRIEROM: grid-based variable source area soil-water erosion and deposition model

Kim, S.J.; Steenhuis, T.S.

Transactions of the ASAE 44(4): 853-862


ISSN/ISBN: 0001-2351
Accession: 003780151

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Erosion in a variable source area and the sediment in surface runoff have a major impact on soil conservation and water quality. It is necessary to locate the soil erosion areas and the paths of sediment transport efficiently to alleviate potential soil loss problems and protect water quality. The objective of this study was to predict temporal variations and spatial distributions of sediment transport in a variable source area for storm events. A GRId-based soil-water EROsion and deposition Model (GRIEROM) is described. This model uses ASCII-formatted map data supported by the GRASS Geographic Information Systems (GIS) and generates distributed results such as sediment concentration and flux in overland flow areas. GRISTORM was adopted for the hydrological processes. A process-based soil erosion concept was adopted to simulate soil-water erosion and deposition. The model deals separately with rill and sheet flow and handles vegetation in terms of soil cover. The model was applied to a 170 ha watershed located in the Northern Catskill region of New York. The initial soil moisture conditions for storm events were based on calibrated values from a Soil Moisture Routing (SMR) model and were adjusted to include soil moisture variations within a day. Predicted flows from four storm events in 1993 were compared with observed flows at the watershed outlet for hydrologic calibration. The average Nash-Sutcliffe efficiency for predicting flow at the outlet using calibrated data was 0.847. Parameters related to sheet/rill flow on bare soil were more sensitive than those on vegetated soil. Sediment depositability (phi) proved to be the most sensitive parameter, followed by the low value of soil erodibility (eta). The Nash-Sutcliffe efficiencies for predicting sediment yield at the outlet for the two storms were negative because of additive prediction and time error of sediment concentration, respectively. The average Nash-Sutcliffe efficiency for another two storms was 0.476. The temporal variations and spatial distributions of overland flow and sediment areas were presented using GRASS. These presentations suggest that most sediment was transported to the stream from the areas that had high overland flow velocities.