Modeling of two-dimensional overland flow in a vegetative filter

Abstract

Water transports sediment and other pollutants through vegetative filters. It is often assumed that the overland flow is uniformly distributed across the vegetative filter, but this research indicates otherwise. The objective of this study was to model the two-dimensional overland water flow through a vegetative filter, accounting for variation in microtopography, infiltration, and surface roughness. Overland flow was monitored in two areas (east and west grid) of an established vegetative filter. The two areas were surveyed in detail to determine the spatially varying microtopography. Soil hydraulic properties were gathered at the site to represent the spatial variation in soil hydraulic properties. Runoff from four irrigation events was monitored. The inflow rate, outflow rate, and maximum depth of flow were measured at multiple locations. Simulation of the flow processes was performed using the physically based, distrusted model, MIKE SHE. Simulations were performed with constant and variable topography and constant and variable soil hydraulic properties. The variable topography significantly impacted the outflow hydrographs for both the areas. The variable soil hydraulic properties impacted the outflow hydrographs with greater impact in the west grid area than the east grid area. The outflow rate at the downstream edge of the vegetative filter varied with position along the downstream edge of the filter indicating flow is not uniformly distributed in the vegetative filter.

Citation

Helmers, Matthew J.; Eisenhauer, Dean E.; Franti, Thomas G.; Dosskey, Michael G. 2002. Modeling of two-dimensional overland flow in a vegetative filter. In: 2002 ASAE Annual International Meeting / CIGR XVth World, Chicago, Illinois. 18 p.