The impact of rock check dams in southern Arizona

Project Overview

Rock check dams are used throughout the world to mitigate erosion problems on degraded lands. Small rock dams have been used for centuries to alter runoff and sediment. Today, rock check dams are being used in rangeland restoration projects throughout the southwestern US.

These low-tech, non-engineered structures are commonly constructed in eroding channels where they cause sediment to deposit. The sediment stores moisture and creates conditions for the germination and growth of vegetation. Vegetation then causes more sediment to deposit and a feedback loop is created whereby channels are healed and vegetation is restored.

In 2008, a research project was initiated by scientists at the ARS - Southwest Watershed Research Center to quantify the impacts of rock check dams on runoff, sediment, and channel morphology. Thirty-seven porous rock structures were built on two small instrumented watersheds the Santa Rita Experimental Range in southern Arizona, USA. The watersheds are located on an alluvial fan at the base of the Santa Rita Mountains.

Each watershed is equipped with a rain gauge, supercritical flow flume, and sediment sampler. Thirty-five years of historical rainfall and runoff, and sediment data are available to compare with data collected after check dam construction.

Please see the project publications for detailed research results and data.

Post-construction measurements of channel geometry and longitudinal channel profiles are being compared with pre-construction measurements to characterize the impact of check dams on sediment retention and channel morphology.

Ultimately vegetation will mitigate soil erosion. The photo sequences from 2009 through 2020 below document changes in vegetation in response to the check dams.

Publications

Polyakov, V.O., Nichols, M.H., McClaran, M., Nearing, M.A. 2014. Effect of check dams on runoff, sediment yield and retention on small semi-arid watersheds. Journal of Soil and Water Conservation. 69:414-421. https://doi.org/10.2489/jswc.69.5.414

Nichols, M.H., Polyakov, V.O., Nearing, M.A., Hernandez, M. 2016. Semiarid watershed response to low-tech porous rock check dams. Soil Science. 181(7):275-282. doi: 10.1097/SS.0000000000000160

Nichols, M.H., Polyakov, V.O. 2019. The impacts of porous rock check dams on a semiarid alluvial fan. Science of the Total Environment. 664:576-582. https://doi.org/10.1016/j.scitotenv.2019.01.429

Original posting (with pictures): https://storymaps.arcgis.com/stories/0a85c57365ba493391257f6eb18dd2be