Water-Harvesting Applications for Rangelands Revisited

摘要

Although water-harvesting techniques have been used effectively in irrigated agriculture and domestic water supplies, there seems to have been little continued exploitation of the same techniques in arid and semiarid rangeland water conservation. A review of the history of rangeland water harvesting allows identification of the methods that have been useful in the past and that would likely be effective in the future. It seems that relatively simple water-harvesting approaches work best on rangelands, particularly water-ponding dikes to stimulate vegetation growth. Experience from rangeland water harvesting in New Mexico and other locations in the Southwest indicates that the approach is a long-term solution that produces significant vegetation growth, but generally only 10-15 years after installation because of the sporadic and spatially distributed nature of the summer monsoon rainfall. Additionally, the use of water-ponding dikes seems to most reliably produce an "island" of enhanced soil moisture and increased habitat cover and forage. Water-ponding dikes are easy and relatively inexpensive to construct and produce a pattern of vegetation similar to naturally occurring banded vegetation. Even very shallow dikes (7.5 cm) have been shown to produce a significant vegetation response. As climate changes our water supplies, historical techniques of water harvesting used for over 9,000 years are viable rangeland water conservation alternatives now and in the future for adapting to such changes.