SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Farm-level optimization of BMP placement for cost-effective pollution reduction 
Authors:Gitau, M.W., T.L. Veith, and W.J. Gburek 
Journal:Transactions of the ASAE 
Article ID: 
URL (non-DOI journals):http://ddr.nal.usda.gov/handle/10113/9729 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:model interface 
Secondary Application Category:pollutant cycling/loss and transport 
Watershed Description:300 ha farm (located in Town Brook watershed; southeast New York) 
Calibration Summary:1992-2002: annual r2 & E = .99 & .84 monthly r2 & E = .76 & .44 
Validation Summary: 
General Comments:SWAT was interfaced with a genetic algorithm and a BMP tool to perform the analysis. Optimal BMP scenarios were determined using a 60% P loss reduction target and cost increase cost increase of $28,551 (relative to the baseline). Selected management practices and costs are reported for two near optimal scenarios. 
Abstract:With best management practices (BMPs) being used increasingly to control agricultural pollutant losses to surface waters, establishing the environmental effectiveness of these practices has become important. Additionally, cost implications of establishing and maintaining environmentally effective BMPs are often a crucial factor in selecting and adopting BMPs. This article considers both water quality and economic concerns and presents a methodology developed for determining costeffective farm- or watershed-level scenarios through optimization. This optimization technique uniquely incorporates three existing tools: a genetic algorithm (GA), a watershed-level nonpoint-source model (Soil and Water Assessment Tool, SWAT), and a BMP tool. The GA combines initial pollutant loadings from SWAT with literature-based pollution reduction efficiencies from the BMP tool and with BMP costs to determine cost-effective watershed scenarios. The methodology was successfully applied to a 300 ha farm within the Cannonsville Reservoir watershed, a phosphorus (P) restricted reservoir within New York City’s water supply system. An average reduction in dissolved P of 60% over the lifetime of the BMPs was set as the pollutant target. A baseline scenario was established to represent practices on the farm before BMP implementation. The most costeffective scenario for the farm, under the presented methodology, achieved a cost-effectiveness of 0.6 kg dissolved P reduction per dollar spent per year. Additionally, the methodology determined alternative scenarios for the farm, which met the pollution reduction criterion cost-effectively. The methodology, as developed, is extendable to multi-farm or watershed-level evaluations.