Abstract
Abstract. Modeling of sediment dynamics for developing best management practices of reducing soil erosion and of sediment control has become essential for sustainable management of watersheds. Precise estimation of sediment dynamics is very important since soils are a major component of enormous environmental processes and sediment transport controls lake and river pollution extensively. Different hydrological processes govern sediment dynamics in a river basin, which are highly variable in spatial and temporal scales. This paper presents a process-based distributed modeling approach for analysis of sediment dynamics at river basin scale by integrating sediment processes (soil erosion, sediment transport and deposition) with an existing process-based distributed hydrological model. In this modeling approach, the watershed is divided into an array of homogeneous grids to capture the catchment spatial heterogeneity. Hillslope and river sediment dynamic processes have been modeled separately and linked to each other consistently. Water flow and sediment transport at different land grids and river nodes are modeled using one dimensional kinematic wave approximation of Saint-Venant equations. The mechanics of sediment dynamics are integrated into the model using representative physical equations after a comprehensive review. The model has been tested on river basins in two different hydro climatic areas, the Abukuma River Basin, Japan and Latrobe River Basin, Australia. Sediment transport and deposition are modeled using Govers transport capacity equation. All spatial datasets, such as, Digital Elevation Model (DEM), land use and soil classification data, etc., have been prepared using raster "Geographic Information System (GIS)" tools. The results of relevant statistical checks (Nash-Sutcliffe efficiency and R–squared value) indicate that the model simulates basin hydrology and its associated sediment dynamics reasonably well. This paper presents the model including descriptions of the various components and the results of its application on two case study areas.
Highlights
Soil erosion and excessive sedimentation are recognized as a major problem arising from deforestation, agricultural intensification, urbanization and land degradation
A number of process-based sediment transport models have been produced by researchers over the past four decades (Bhattacharya et al, 2007), such as European Soil Erosion Model (EUROSEM) (Morgan et al, 1993), Water Erosion Prediction Project (WEPP) (Nearing et al, 1989), Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS) (Beasley et al, 1980), etc
The digital elevation model (DEM) of 500-m grid spacing has been used in simulation which was originally taken from SRTM data of 90-m resolution
Summary
Soil erosion and excessive sedimentation are recognized as a major problem arising from deforestation, agricultural intensification, urbanization and land degradation. A number of process-based sediment transport models have been produced by researchers over the past four decades (Bhattacharya et al, 2007), such as European Soil Erosion Model (EUROSEM) (Morgan et al, 1993), Water Erosion Prediction Project (WEPP) (Nearing et al, 1989), Areal Nonpoint Source Watershed Environment Response Simulation (ANSWERS) (Beasley et al, 1980), etc. EUROSEM does not consider sediment dynamics in river systems separately Another model, WEPP, introduced by US Department of Agriculture (Flanagan and Nearing, 1995), is able to estimate hillslope soil erosion and sediment movement using process-based distributed hydrological modeling. The present study has focused only on the suspended sediment simulation in the river basin, where clay and very fine silt were excluded
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