Determining sediment deposition dynamics influenced by check dams in a semi‐arid mountainous watershed

• Published in: Earth surface processes and landforms Vol. 49; no. 6; pp. 1849 - 1857
• Main Authors: Polyakov, Viktor, Nichols, Mary, Cavanaugh, Michelle
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.05.2024
• Subjects: Anthropogenic factors; Arid environments; Arid zones; Aridity; Caesium 137; cesium; Cesium 137; Cesium isotopes; Cesium radioisotopes; check dam; Check dams; Dam construction; Dams; Dating techniques; Deposition; Fallout; Flash flooding; Flash floods; Headwaters; Human influences; Lead isotopes; Mitigation; Mountainous areas; Mountains; Sediment; Sediment analysis; sediment chronology; Sediment concentration; Sediment control; Sediment sorting; sedimentation; Sediments; Service life assessment; soil erosion; Storage capacity; Storage conditions; Watersheds
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.5802

Semi‐arid environments are characterized by infrequent large magnitude rainfalls that produce flash flood events with high sediment concentration. Control structures such as check dams are widely used in this environment for mitigation. However, their impact on the overall sediment balance of watersheds, particularly those severely affected by anthropogenic activity, is sparsely documented. This study used topographic measurements, sediment analysis, and fallout isotope techniques to assess the effectiveness and service life of 18 rock and masonry check dams that were constructed in the 1930s for controlling sediment fluxes in an 11 ha mountainous watershed in southern Arizona. All of the dams are currently filled with sediment resulting in reduction of local channel gradients by 35 to 71% to between 0.04 and 0.28 depending on location within the reach. Sedimentation occurred over multiple decades at a relatively slow average rate of 0.59 t ha−1 y−1 indicating low instantaneous retention efficiency. The smaller headwater dams were filled soon after construction; however, their share of the overall storage capacity was minor. Although evaluation of 137Cs was an effective method for dating sediment, the 210Pb dating method was not satisfactory because of sediment sorting effects and complex deposition patterns. The abundance of similar control structures in the region points to the opportunity to better understand the process impacts of check dams over multiple decades to inform planning and design of their use in future mitigation projects. Sediments stored behind check dams contain a record of long‐term landscape disturbances. Distribution of fallout isotope 137Cs within the vertical profile of alluvium and location of its peak allowed to determine the rate of sedimentation and erosion on contributing watershed.