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An Upgraded Software Application Can Better Predict Erosion Processes of Earthen Dams

Contact: Maribel Alonso

July 27, 2021

Scientists and engineers at the USDA's Agricultural Research Service (ARS) collaborated with USDA's Natural Resources Conservation Service (NRCS) and Kansas State University (KSU) to extend applicability of a computational model that can evaluate vulnerabilities in earthen dams and predict possible dam breaches that could have serious consequences.

The Windows Dam Analysis Modules (WinDAM) and its recent version, WinDAM C, is a software application composed of various computational algorithms that can analyze and predict situations where overtopping or internal erosion can cause a failure in cohesive earthen dams.

"We wanted to develop a reliable tool that not only predicts the erosion progression and potential breach of the dam when water spills over it, but to also predict the erosion progression and breach if the dam were to develop an internal hole," said Sherry Hunt, Research leader with the Hydraulic Engineering Research Unit at Stillwater, OK. "With WinDAM C, we can determine how quickly a cohesive earthen dam may erode and the timing of the breach by using scenarios based on soil parameters, reservoir storage, and water flow into the reservoir."

USDA-NRCS assists local sponsors in the construction of earthen dams through the Watershed and Flood Prevention Operations Program. Local sponsors are required to maintain the dams using NRCS guidelines. Over the years, land-use changes and population growth coupled with environmental and weather stresses placed on these dams have led to the need to rehabilitate these dams. This has led to the development of the USDA-NRCS Watershed Rehabilitation Program. New strategies were needed to prioritize the more than 6,000 dams that have surpassed their planned service life. WinDAM C is currently being used to identify earthen dam vulnerabilities and assist in the prioritization of sites for rehabilitation or removal from service. This software was developed using large scale physical models and validated using real-world case studies.

Hydraulic engineers Greg Hanson and Sherry Hunt view the start of a headcut-widening test
Hydraulic engineers Greg Hanson and Sherry Hunt view the start of a headcut-widening test, which will help them understand the widening component of the dam-breach process.

Earthen dams are primarily built with compacted layers of soil. Even though earthen dams are safe, with time and changes in the environment, water can spill over the dam, or the dam can develop vulnerabilities in its structure, causing a leak and eventually a breach. Internal erosion of dams may be initiated by animal burrows, decaying tree roots, or flaws due to poor soil compaction along the main principle spillway pipe.

Dams are important to USDA because these infrastructures have a significant role in agriculture in rural areas, as they are critical for irrigation purposes and water supply in livestock production. Dams also provide numerous benefits, including downstream flood control, municipal water supplies for economic growth and recreational opportunities such as those we enjoy during the summer season like fishing, boating, hiking, swimming, and camping.

"There is more work to be done. Predicting dam failure is not only a national problem but a global problem. Scientists and engineers must continue this ongoing worldwide effort to validate current and new models to be effective tools for identifying vulnerabilities to prevent possible dam breaches. Public safety is paramount for USDA." stated Hunt.

The WinDAM C study was published in the American Society of Agricultural and Biological Engineers.

The Agricultural Research Service is the U.S. Department of Agriculture's chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.