Process-based distributed modeling approach for analysis of sediment dynamics in a river basin

摘要

Modeling of sediment dynamics for developing best management practices ofreducing soil erosion and of sediment control has become essential forsustainable management of watersheds. Precise estimation of sedimentdynamics is very important since soils are a major component of enormousenvironmental processes and sediment transport controls lake and riverpollution extensively. Different hydrological processes govern sedimentdynamics in a river basin, which are highly variable in spatial and temporalscales. This paper presents a process-based distributed modeling approachfor analysis of sediment dynamics at river basin scale by integratingsediment processes (soil erosion, sediment transport and deposition) with anexisting process-based distributed hydrological model. In this modelingapproach, the watershed is divided into an array of homogeneous grids tocapture the catchment spatial heterogeneity. Hillslope and river sedimentdynamic processes have been modeled separately and linked to each otherconsistently. Water flow and sediment transport at different land grids andriver nodes are modeled using one dimensional kinematic wave approximationof Saint-Venant equations. The mechanics of sediment dynamics are integratedinto the model using representative physical equations after a comprehensivereview. The model has been tested on river basins in two different hydroclimatic areas, the Abukuma River Basin, Japan and Latrobe River Basin,Australia. Sediment transport and deposition are modeled using Goverstransport capacity equation. All spatial datasets, such as, DigitalElevation Model (DEM), land use and soil classification data, etc., havebeen prepared using raster "Geographic Information System (GIS)" tools.The results of relevant statistical checks (Nash-Sutcliffe efficiency andR–squared value) indicate that the model simulates basin hydrology and itsassociated sediment dynamics reasonably well. This paper presents the modelincluding descriptions of the various components and the results of itsapplication on two case study areas.