HR: 1340h
AN: H13C-0415    [Abstracts]
TI: Distributed Model for Overland Hydrology, Sediment and Chemical Transport in Watersheds
AU: * Zhang, Z
AF: Analytical Services Inc. Environmental Laboratory, EP-W 3909 Halls Ferry Road, Vicksburg, MS 39180 United States
AU: Johnson, B E
AF: Environmental Laboratory Engineer Research and Development Center, EP-W 3909 Halls Ferry Road, Vicksburg, MS 39180 United States
AU: Dortch, M S
AF: Environmental Laboratory Engineer Research and Development Center, EP-W 3909 Halls Ferry Road, Vicksburg, MS 39180 United States
AB: Contaminants from non-point or distributed sources can adversely affect the quality of downstream waters and groundwater. Reliable models can help understanding the fate and transport of contaminants on the overland as well as the shallow subsurface and lead to better management strategies of the environmental response and security. In this study, a watershed is represented by discretizing contributing areas into a cascade of one dimensional (1D) overland flow using DEM data. A distributed watershed model is developed to simulate overland flow and processes of sediment and chemical detachment and their transport in runoff. The model, consisting of linked hydrology, sediment and chemical transport components, is physically based and process oriented. In the model, the overland flow component uses fully implicit nonlinear finite difference scheme combined with a linear scheme to numerically solve the 1D kinematic wave equations. The erosion and sediment transport component simulates the movement of eroded soil along with the movement of surface water, calculates the sediment transport capacity and the potential sediment supply, chooses whichever is less and routes it throughout the watershed. Erosion is the sum of splash detachment by raindrops and flow detachment by runoff. The process of chemical transport in the soluble phase is simulated by a 1D advection, diffusion and adsorption-desorption processes equation. Chemical transport by suspended sediment is described by the advection-diffusion equations with the sink-source term including erosion-deposition exchange processes. Both sediment and chemical transport components are developed as separate blocks of the watershed overland modeling system. A 1D model in overland studies can provide plenty of useful information without requiring many input parameters. The model will be incorporated into the Army Risk Assessment Modeling System (ARAMS) as a watershed module to satisfy the need for simulating hydrological, sediment, and chemical transport at different temporal and spatial scales.
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting