Submitted to: Proceedings of the World Water and Environmental Resources Congress
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2005
Publication Date: 6/1/2005
Citation: Clemmens, A.J., Allen, R.G. 2005 Impact of agricultural water conservation on water availability. Proceedings of the World Water and Environmental Resources Congress. p. 535 (pdf) Interpretive Summary: Water resources in many part of the country are increasingly in short supply. This creates competition for limited water resources, sometimes pitting agricultural water users against urban and other water users. Agriculture uses a majority of the water in the country, both diverted from streams and pumped from groundwater. Agriculture is perceived as wasting water. This paper attempts to put irrigated agriculture into context and to describe situations where improving field irrigation systems provide water conservation benefits and where such improvements, while useful for farmers, do not conserve the freshwater supply for a watershed or river basin. The role of water salinity in water conservation considerations is also discussed. These results should be of use to consultants, farm advisors, researchers, Natural Resources Conservation Districts, the Natural Resources Conservation Service, the Bureau of Reclamation, and other government agencies.
Technical Abstract: Agricultural water diversions in the U.S. in 2000 were roughly 153 million acre-feet per year (Hutson et al. 2004), representing 65% of the freshwater diversions (excluding thermoelectric power). The market value of crops sold from irrigated agriculture in the U.S. exceeds $38 billion/year, representing 40% of the market value of all harvested crops on only 9% of the crop land (NASS 2002). Thus while agriculture is an attractive target for obtaining water for other segments of the economy and environment, large shifts in water away from irrigated agriculture may eventually have a negative impact on the economy. Agricultural water conservation is touted as a good method for reducing water diversion while minimizing the impact on production. However, very few studies have documented the actual amount of water saved from agricultural water conservation efforts. In some hydrologic settings, reducing water diversions to agriculture does not automatically save water, since the extra water not consumed may be used downstream. Further, there is evidence that water conservation programs that target improved application efficiency can actually increase water consumption as the result of improvement in irrigation uniformity. There are situations under which improvements in the irrigation systems will reduce the amount of water that is irrecoverably lost or will result in less water quality degradation. In arid environments, water is required for leaching salts brought in with the irrigation water. More water is needed for leaching as the salinity of the water increases. Thus reducing the water salinity can result in less irrigation water demand, potentially making more water available for other uses. In the paper, we provide a framework for examining the impact of water conservation practices and programs on water availability and present examples where water conservation efforts have been successful.