Abstract: Erosion dynamics in semiarid environments is defined by high magnitude, low
frequency rainfalls that produce runoff with high sediment concentration. Check dams are
widely used in this environment as a sedimentation mitigation technique, however their
impact on overall watershed sediment balance is not well known. In 2008 a total of 37 loose
rock semipermeable check dams were installed on two small (4 and 3.1 ha [9.8 and 7.6 ac])
watersheds located on the alluvial fan of the Santa Rita Mountains in southern Arizona. Each
watershed was equipped with a rain gauge, supercritical flow flume, and sediment sampler.
The runoff and sediment yield characteristics following the check dam installation were compared
with 35 years of historical records. Impacts of the check dams on runoff from major
rainstorms were not detectable; however the number of runoff events generated by small (less
than one year recurrence interval) rainstorms decreased by 60%. During four years check
dams retained 75 t (82.6 tn) of sediment (50% of sediment yield) and were filled to more
than 80% of their capacity. Depositional areas upstream of the dams have potential to support
watershed restoration.
Source:Â http://www.tucson.ars.ag.gov/unit/publications/PDFfiles/2202.pdf
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Reports and other documents about Sonoran Desert ecology, management, and conservation. Curated by the not-for-profit Altar Valley Conservation Alliance (AVCA) located outside Tucson, AZ.