Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2007
Publication Date: 7/29/2008
Citation: Clemmens, A.J., Allen, R.G., Burt, C.M. 2008. Technical concepts related to conservation of irrigation and rain water in agricultural systems. Water Resources Research. 44:1-16, W00E03, doi:10.1029/2007/WR006095. Interpretive Summary: Competition for limited water resources sometimes pits 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: Forty percent of freshwater withdrawals in the U.S. are for irrigated agriculture, which contributed 55$ billion to the economy in 2002. Increasing diversions of water for urban, environmental, and other uses will likely decrease water available to agriculture. Agricultural water conservation is touted as a good method for minimizing the impact of such diversions on production. However, there are limitations to true water savings through increasing irrigation efficiency. We focus on four areas: reduction of unnecessary evaporation and transpiration, more effective use of rainfall, reduction of deep percolation water that becomes severely degraded in quality, and reduction of runoff from fields that is not reusable downstream. The wide variety of hydrologic settings makes it difficult to determine true water savings from conservation practices without a thorough analysis. On size does not fit all. On-farm water conservation practices that provide true water savings at one location may be ineffective at another. In large irrigation projects, water delivery limitations often present an obstacle to on-farm water conservation effort. Canal automation is a relatively new technology that promises to remove this water conservation barrier