Abstract
Vegetative filters (VF) are used to remove contaminants from agricultural runoff and improve surface water quality. Techniques are needed to quantify the performance of VF in realistic field settings. The goal of this project was to develop and test a relatively simple and low cost method for sampling overland flow in a VF. The 0.3 m wide sampler has the capacity to sample a flow rate of 1.3 L/s and a total runoff volume of about 20 000 L. The sampler was tested in the laboratory, in field experiments, and using a simulation model. Overall the sampler split ration (SR) is 2180. The SR is essentially constant with flow rate in the range of 0.1 to 1.0 L/s. Computer simulations of overland flow using MIKE SHE indicate that the sampler does not cause significant convergence or divergence of flow when sampling at the downstram edge of the VF. Because of the lower roughness in the VF relative to the row-cropped contributing watershed, longer wing walls are needed to avoid flow convergence when sampling at the leading edge of the buffer. The required length of the wingwall is dependent on land slope, flow rate, and the hydraulic roughness of the filter. The runoff volume and runoff hydrographs that were derived from the sampler agreed well with the measurements taken with flow measurement flumes. Equations were developed to help interpret the data collected with the sampler.
Keywords
Buffers,
vegetative filters,
samplers,
overland flow
Citation
Eisenhauer, D.; Helmers, M.; Brothers, J.; Dosskey, M.; Franti, T.; Boldt, A.; Strahm, B. 2002. An overland flow sampler for use in vegetative filters. In: 2002 ASAE Annual International Meeting / CIGR XVth World Congress, Chicago, Illinois. 16 p.
