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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF MODELS AND CONSERVATION PRACTICES FOR WATER QUALITY MANAGEMENT AND RESOURCE ASSESSMENTS

Location: Grassland, Soil and Water Research Laboratory

Title: Evaluating conservation program success with Landsat and SWAT

Authors
item White, Michael
item Storm, Daniel -
item Busteed, Phillip
item Stoodley, Scott -
item Phillips, Shannon -

Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 2010
Publication Date: May 1, 2010
Citation: White, M.J., Storm, D.E., Busteed, P.R., Stoodley, S., Phillips, S.J. 2010. Evaluating conservation program success with Landsat and SWAT. Environmental Management. 45(5):1164-1174.

Interpretive Summary: Many state and federally funded conservation programs are required to estimate their environmental benefit. The change in pollutant losses from pastures treated with a variety of conservation practices was evaluated in the Lake Wister Basin (Oklahoma). Changes in vegetative cover due to conservation practices were derived from satellite imagery. These data were used with the Soil and Water Assessment Tool (SWAT) to predict changes in phosphorus and sediment delivery to nearby streams for each type of conservation practice, i.e. ponds, improved forages, fencing, and limited grazing. The effectiveness of practices was variable, ranging from very successful to actually increasing pollutant losses. Overall, the conservation program reduced pollutant losses, but if could have been more effective without additional cost. This combination of vegetative cover analysis and SWAT simulation may provide guidance for the selection of conservation measures subsidized in future conservation programs.

Technical Abstract: In the United States, many state and federally funded conservation programs are required to quantify the water quality benefits resulting from their programs. The objective of this research was to evaluate the impact of conservation practices subsidized by the Oklahoma Conservation Commission on phosphorus and sediment loads in the Lake Wister Basin. The construction of new ponds, improved pasture fertility, establishment of improved forage, additional fencing and limited grazing were evaluated. Pond construction reduced phosphorus and sediment loads by 1.8% and 2.1%, respectively, by trapping nutrients and serving as alternative water sources for cattle. Conservation practices designed to increase vegetative cover in grazed pastures were evaluated using Landsat-derived vegetative indices and the Soil and Water Assessment Tool (SWAT). Overall, these conservation practices yielded a 1.9% improvement in vegetative cover and a sediment load reduction of 3.5%. Changes in phosphorus loss ranged from a 1.0% improvement to 3.5% increase. The use of phosphorus containing fertilizers as conservation practice in low productivity pastures was predicted to increase net phosphorus losses despite any improvement in vegetative cover. The net benefit of the practices evaluated in this research was a 5.4% reduction in sediment and a 1.8% to 2.8% reduction in phosphorus to Lake Wister. This combination of vegetative cover analysis and hydrologic simulation was a useful tool for evaluating the effects of conservation practices at the basin scale, and may provide guidance for the selection of conservation measures subsidized in future conservation programs.

Last Modified: 7/27/2014
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