Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: September 24, 2007
Publication Date: December 14, 2007
Citation: Pachepsky, Y.A., Guber, A.K., Sadeghi, A.M., Shelton, D.R. 2007. Probabilistic Evaluation of the Vegetated Filter Strip Efficiency With Respect to Pathogen Removal From Runoff. Fall Meeting of the American Geophysical Union, December 10-14, 2007, San Francisco, CA. Technical Abstract: Vegetated filter strips (VFS) have become an important component of the water quality improvement in watersheds. Relatively little is known about the efficiency of VFSs in retention of manure-borne pathogens that can be important agricultural pollutants. The objective of this work was to evaluate the uncertainty in VFS efficiency caused by the quantifiable variations in major retention factors, i.e. vegetation status, soil infiltration capacity, and rainfall intensity and duration. We have developed the model STIR to simulate the overland transport and loss to infiltration of manure-borne pathogens in VFS. This model was used in Latin Hypercube sampling-based simulations to evaluate the possible variability in pathogenic bacteria breakthrough in VFSs. The sampled model parameters were rainfall intensity, rainfall duration, initial soil water content, Manning roughness coefficient, saturated hydraulic conductivity, shape parameters of soil water retention curve, pathogen partitioning coefficient, pathogen attachment rate, pathogen straining rate, and the dispersivity in the overland flow. Probability distributions of the parameters were selected to represent the USDA-ARS experimental site in Beltsville, MD, where the STIR model was tested with data on E. coli bacteria. Relatively long high-intensity rainfalls, low hydraulic conductivities, high soil moisture contents before the rainfall, and high dispersivities were the main reasons of the strip partial failure. However, the unfavorable conditions and there combinations were relatively rare, and the removal efficiency of the 6-m long VFS at the edge of 200-m long field was less than 100 % for 5 % of simulation scenarios, and less than 75 % for 2.5 % of simulation scenarios. The probabilistic characterization of the VFS efficiency with site-specific soil and weather properties can be useful in making decisions on VFS placement with respect to manure-borne pathogens.