Water-harvesting applications for rangelands revisited

Authors: Rango, Albert; Havstad, Kris

Submitted to: Environmental Practice
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2009
Publication Date: 6/15/2009
Citation: Rango, A., Havstad, K.M. 2009. Water-harvesting applications for rangelands revisited. Environmental Practice. 11(2):84-94.

Interpretive Summary: Many rangeland restoration treatments are unsuccessful because of insufficient water supplies, especially in arid and semiarid regions. Water harvesting approaches have been used in rangeland successfully in the past, but these applications are frequently overlooked. A detailed review of rangeland water harvesting the western U.S. reveals that simple techniques work well including water ponding dikes to promote forage growth, dirt stock tanks to water livestock watering, and more complex water spreaders useful over large areas. In arid and semiarid regions, it may take 10-15 years to stimulate increased vegetation growth. Future landscape level rangeland treatments will have a greater chance of succeeding if the incorporate water harvesting in the project planning. Land management agencies like the Natural Resources Conservation Service and the Bureau of Land Management along with private ranchers are the likely users of rangeland water harvesting.

Technical Abstract: Although water harvesting techniques have been used effectively in irrigated agriculture and domestic water supplies, there seems to have been little exploitation of the same techniques in arid and semiarid rangeland restoration. A review of the history of rangeland water harvesting allows identification of the methods that have been useful in the past and which would be likely effective in the future. It seems that relatively simple water harvesting approaches work best on rangelands including water ponding dikes to stimulate vegetation growth, stock tanks for livestock watering, and possibly the use of larger-scale water spreaders, although their complexity sometimes can lead to problems in operational use. Rangeland water harvesting in the southwest U.S. indicates that the approach is a long-term solution that produces significant vegetation growth generally after 10-15 years 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 increased soil moisture and increased 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 (7.5cm) produce ponds and a significant vegetation response. Research needs to be done to see if the bands of vegetation behind the dikes will function like banded vegetation and expand to larger areas. As climate change continues to impact our water supply, the techniques of water harvesting will become a viable rangeland water conservation alternative in the future.