Submitted to: European Geophysical Society Meeting
Publication Type: Proceedings
Publication Acceptance Date: January 13, 2004
Publication Date: April 26, 2004
Citation: Pachepsky, Y.A., Kouznetsov, M.Y., Shelton, D.R., Roodsari, R., Shirmohammadi, A., Sadeghi, A.M., Starr, J.L. 2004. Two-dimenional representation and modeling of bromide and microbial transport at a Hillslope Grass Buffer. In: Proceedings of the 1st General Assembly of the European Geophysical Union, April 25-30, 2004, Nice, France. Paper No. 05011.
Hillslope grass buffers are used to prevent water pollution from agricultural sources. The objective of this work was to develop and test a mechanistic model of coupled surface and subsurface flow and transport of bacteria and a conservative tracer at a hillslope. The testing should indicate what level of complexity and observation density might be needed to capture essential processes in the model. We combined the three-dimensional FEMFLOW model of saturated-unsaturated subsurface flow with the Saint-Venant model for runoff. Results were visualized in the GMS environment. The model was tested with data on bacteria and bromide transport from manure at vegetated and bare 6-m long plots during simulated rainfall events. No need in calibrating water retention parameters was encountered. The same manure release parameters could be used both for simulations of Br and bacteria. Surface straining rates were similar for bromide and bacteria. Simulations of Br and bacteria concentrations were least successful for the funnels closest to the source. This could be related to the finger-like flow of the manure from the strip along the bare slopes, to transport of Br and bacteria with manure colloids that became strained at the grass slope, and to presence of micro-ponds at the grassed slope. The two-dimensional model abstraction of the actual 3D transport worked well for flux-averaged concentrations. The flexible software developed in this work is suitable to simulate surface and subsurface transport of agricultural contaminants on hillslopes and to evaluate efficiency of grass strip buffers, especially when lateral subsurface flow is important.