Seventy percent of the precipitation which falls on the United States and 90 to 95 percent of that which falls on the arid Southwest is lost to evapotranspiration. Water harvesting is a means for salvaging some of this loss and alleviating the growing water problem. Catchments are the most efficient means of harvesting water in arid regions. Currently, however, their use as a source of water for irrigation is uneconomical, but they are practical for supplying water for wildlife, livestock, and domestic uses where there is no inexpensive surface or well water available. In this study one type of relatively inexpensive catchment, the gravel-covered polyethylene-lined type, is considered. The protective gravel cover, which can be the most costly material item in the construction of the catchment if imported, is evaluated. The effect of soil in the gravel cover and other factors affecting catchment efficiency are also considered. It was concluded that the gravel-covered polyethylene-lined catchment can provide relatively inexpensive, clear, high-quality water in low-rainfall areas if gravel is available near the site and the construction is properly carried out.
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