Evaluating efficiencies and cost-effectiveness of best management practices in improving agricultural water quality using integrated SWAT and cost evaluation tool

Authors: LIU, YAOZE - Purdue University; WANG, RUOYU - University Of California, Davis; GUO, TIAN - Heidelberg University; ENGEL, BERNARD - Purdue University; Flanagan, Dennis; LEE, JOHN - Purdue University; LI, SIYU - State University Of New York (SUNY); PIJANOWSKI, BRYAN - Purdue University; COLLINGSWORTH, PARIS - Purdue University; WALLACE, CARLINGTON - Pennsylvania State University

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2019
Publication Date: 7/18/2019
Citation: Liu, Y., Wang, R., Guo, T., Engel, B.A., Flanagan, D.C., Lee, J.G., Li, S., Pijanowski, B.C., Collingsworth, P.D., Wallace, C.W. 2019. Evaluating efficiencies and cost-effectiveness of best management practices in improving agricultural water quality using integrated SWAT and cost evaluation tool. Journal of Hydrology. 577:123965. https://doi.org/10.1016/j.jhydrol.2019.123965.
DOI: https://doi.org/10.1016/j.jhydrol.2019.123965

Interpretive Summary: Runoff and soil erosion from crop fields can cause serious problems in off-site streams and lakes. In addition to soil that moves as sediment in the runoff, there are also chemicals in the water and attached to the sediment, especially nutrients such as phosphorus (P) and nitrogen (N) that are used in crop production. In fresh water lakes P and N act as a food source for algae, and can cause large growths of these aquatic plants. Some types of algae also produce toxins that can poison people and animals that drink or come in contact with the water. One large area of these types of problems is Lake Erie, and many scientists, conservationists, and policymakers are looking for ways to decrease the nutrients and algae in the lake. Farmers are also concerned, but need ways to reduce nutrient losses while also maintaining a profitable crop production system. In this study we combined a water quality computer simulation model with a cost estimation tool, to determine both the effectiveness of management practices at reducing P losses and the most cost effective practices or combinations of practices. We applied the modeling system to a small watershed area in the western Lake Erie basin, and used typical cropping and management systems and site-specific climate, soils, and topographic inputs to the model. We also used recommended best management practices and cost estimates from the USDA Natural Resources Conservation Service to evaluate different systems and their effectiveness in reducing P losses, and which systems cost less. In this analysis we found that filter strips at the edges of fields in critical areas in the watershed were most cost effective in reducing P losses. This research impacts scientists, farmers, conservation personnel, and others working to reduce water quality problems in Lake Erie and elsewhere. The procedure can be used in other locations to address similar pollutant problems for N or P losses.

Technical Abstract: Best management practices (BMPs) can reduce nutrient loadings from the Maumee River watershed and help address harmful algal blooms (HABs) in Lake Erie. The Soil and Water Assessment Tool (SWAT) and a new BMP cost tool were integrated to explore efficiencies and cost-effectiveness of BMPs in an agricultural catchment with various scenarios, including individual BMPs applied in 100% of suitable areas, individual BMPs targeting Dissolved Reactive Phosphorus (DRP) and Total Phosphorus (TP) critical areas, and BMPs implemented in series. Additional scenarios were simulated by applying BMPs based on cost-effectiveness rankings starting from the most cost-effective until reaching the watershed management plan goal of reducing March-July DRP/TP losses by 40%. BMPs implemented in series, which reduced more pollutants than individual BMPs, were not as cost-effective as some individual BMPs. Among all scenarios, filter strips targeting DRP/TP critical areas were the most cost-effective in reducing yearly/spring DRP/TP losses. To reduce March-July DRP/TP losses by 40%, implementing BMPs one by one in critical areas based on the cost-effectiveness rankings of individual BMPs in the DRP/TP critical areas was the most cost-effective. These results and the overall approach can help create stormwater management strategies to cost-efficiently improve water quality.