Modeling hydrology and sediment transport in vegetative filter strips
Sediment and sediment bounded pollutants carried by runoff from non-point sources is a major pollutant of water bodies. Vegetative filter strips (VFS) are bands of planted or indigenous vegetation used to control runoff and sediment outflow from disturbed areas. This work presents and validates a research model to study the hydrology and sediment movement in VFS. This was accomplished in four steps. The numerical solution of the overland flow kinematic wave equations is subject to numerical problems when a rapid change in parameters is encountered (kinematic shock). An improved finite element method, i.e. a Petrov-Galerkin (PG) formulation, is presented. The formulation depends on four parameters. The PG method decreased the mean sum of square error by about 65%. The finite element overland flow solution is modified and linked to the Green-Ampt infiltration equation to form a VFS-specific hydrology model. An analysis of the effect of different filter properties (soil type, slope, surface roughness, buffer length) on the major hydrological out-puts (runoff volume, velocity and peak flow rate) is made. Optimal filter performance (i.e. reduction in runoff volume, velocity and peak flow rate) is found for soils with high infiltration capacity, dense grass cover and small slopes. A sediment transport/filtration submodel (based on the University of Kentucky model) is added to the hydrology submodel. The interaction between submodels and a natural event application case to illustrate the capability of the model and its various outputs is presented in detail. An analysis of sensitivity and a field validation are performed. The most sensitive parameters are soil initial water content, vertical saturated hydraulic conductivity, particle class and grass spacing. The model predictions were compared with a set of natural events from an experimental site in the North Carolina Piedmont. In general the model performs well.
- Research Organization:
- North Carolina State University, Raleigh, NC (United States)
- OSTI ID:
- 39336
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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