Location: Southwest Watershed Research
Title: Effect of check dams on runoff, sediment yield and retention on small semi-arid watersheds 2202 Authors
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2014
Publication Date: N/A
Interpretive Summary: This study looks at the potential for using low-tech, rock check dams as runoff and erosion control structures in a semi-arid environment. We used two small watersheds that have been monitored for surface water storm runoff and sediment export over the last 3 decades. The rates and amounts of surface water runoff were not appreciably changed after the installation of the check dams, however the structures did retain a significant amount of sediment over the four year period of the experiment. After the experiment the dams were approximately 80% filled to capacity for sediment retention. We will continue to monitor the experiment in the future, particularly looking for the potential for the depositional areas above the structures to act as a reservoir in retain more water than would otherwise be retained, thus allowing for the establishment of vegetation in the channels. Check dams have the potential to make a difference in sediment movement in the semiarid environment, at least over the short term, if properly installed and maintained.
Technical Abstract: Erosion dynamics in semi-arid environments are defined by high magnitude, low frequency rainfalls that produce runoff with high sediment concentration. Check dams are widely used in this environment as sedimentation mitigation technique, however their impact on overall watershed sediment balance is not well known. In 2008 a total of 37 loose rock semi permeable check dams were installed on two small (4.0 and 3.1 ha) watersheds located on the alluvial fan of the Santa Rita Mountains in southern Arizona, USA. Each watershed was equipped with a rain gauge, supercritical flow flume, and sediment sampler. The erosion and flow dynamics following the check dam installation were compared with 35 years of historical records. Check dams did not significantly affect runoff characteristics. During 4 years they retained 50% of sediment from runoff and were filled to more than 80% of their capacity. Depositional areas upstream of the dams have potential to support watershed restoration.