WWRC 85-16
Hydrologic Impacts on the Salt River Due to Changes
in Irrigation Systems
Abstract
The Salt River drainage basin (Star Valley) is an agricultural
watershed of 829 mi2 in western Wyoming. Starting in 1971 several
irrigation projects were completed that converted surface irrigation
systems to sprinkler irrigation systems on approximately one-half of the
irrigated acres in the valley. This conversion resulted in less total
water being diverted from streams for the sprinkler systems than was the
case for the surface systems on the same irrigated acreage.
Salt River stream flows were hydrologically analyzed and a
comparison made of the flows prior to and after conversion to sprinkler
systems. A test of mean monthly flows showed that spring flow increased
significantly ( a = 0.05) by 58.7% following the conversion to
sprinklers. The Salt River flows were also compared with flow of the
Greys River, which drains a non-agricultural watershed immediately adjacent
to the Salt River, using the double mass analysis. This test again
showed higher spring flows and also lower fall flows were evidently a
consequence of irrigation practices rather than climatological factors.
Analysis of annual flood peaks was accomplished by several
hydrologic and statistical tests. Included were a comparison of flood
frequency distributions, a test of stationariness and a test of
homogeneity. These tests revealed that mean annual flood peak increased
significantly (a = 0.05) by 47.0%.
Water Resources Publications List
Water Resources Data System Library |
Water Resources Data System Homepage
