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2022 Annual Report
Objectives
Objective 1: Improve the WinDAM model to predict the erosion of complex embankment geometries and composite materials, and the allowable overtopping flows for alternative materials, including articulated concrete blocks or riprap integrated with vegetation.
Subobjective 1A: Quantify the impact of complex vegetated embankment geometries on erosion process during overtopping including: convergence zones at the intersection of the earthen embankment and valley walls and embankment berms and toes.
Subobjective 1B: Quantify the impact of changes in soil materials (specifically zoned vs. homogenous) on erosion processes and rates of earthen embankment erosion and breach.
Objective 2: Develop engineering guidance to determine hydraulic performance of alternative stepped chute designs.
Subobjective 2A: Develop guidelines for alternative step and/or chute geometry for stepped chutes constructed over existing earth dams.
Subobjective 2B: Improve engineering design guidance for stilling basin design for stepped chutes.
Objective 3. Engage Missouri River Basin stakeholders through our University of Missouri Research and Extension partners to characterize water resource managers’ and producers’ behavior, attitudes, and economic considerations with respect to irrigation water use, conservation, and flood mitigation; and to introduce them to analytical based decision aides for evaluating new technologies, best management practices, and cost-benefit assessment.
Objective 4. Develop holistic stochastic optimization models, risk assessment, and decision support tools to improve sustainable agriculture production water management practices, while enhancing long-term landscape health in temperate environments. These models will focus on water availability, water storage, and flood mitigation with dynamic economic assessments. This objective will be met through a collaborative effort between HERU and our University of Missouri partners.
Approach
Large-scale physical model testing on intergraded surface protection (i.e. vegetation or vegetation integrated with riprap and/or ACBs) of steep embankment channels coupled with data from vegetated channel databases will be used to develop knowledge on erosion of complex embankment geometries (i.e. berms and convergence zones) and the materials (i.e. vegetation, riprap, and/or ACBs) intergraded within the embankment as surface protection. Large and small-scale models will be used to evaluate and to develop knowledge of fundamental processes and rates of erosion of zoned embankment materials. These tests will provide knowledge to develop key algorithms related to earthen embankment erosion. Large and small-scale physical models will be used to develop knowledge on the affect step and/or chute geometry has on the design of stepped chutes and stilling basins. Data from these physical models will be used to develop new relationships and/or tools or expand the use of existing technology for embankment erosion prediction and spillway and stilling basin design. USDA-ARS HERU scientists will collaborate with other ARS, government, university, international scientists, and consultants to carry-out these objectives. Research results will be integrated into new or existing evaluation tools, software, design criteria, and management practices; thereby, allowing for the continued service and increased benefit of our nation's multi-purpose agricultural infrastructure.
Progress Report
This is the final report for plan 3072-13000-010-000D "Development of Engineering Tools for the Design and Rehabilitation of Safe, Efficient Embankment Protection Alternatives, Hydraulic Structures, and Channels. It was replaced with 3072-13000-011-000D "Development of a Monitoring Network, Engineering Tools, and Guidelines for the Design, Analysis, and Rehabilitation of Embankment Dams, Hydraulic Structures, and Channels."
During the life of the project, an ARS researcher at Stillwater, Oklahoma, along with their cooperators made significant progress on Objective 1 with the release of new Windows Dam Analysis Modules (WinDAM) C versions through maintenance and routine updates to computer code. WinDAM C is a computer model used for analyzing the erosion processes and breach timing of earthen embankments subjected to water flowing over the top of a dam or through an internal opening in a dam. Researchers constructed steep embankment channels to examine erosion processes of vegetal surfaces of complex embankment geometries (e.g., berms located at the downstream embankment toe and the intersection of the dam and the natural landscape). Field support was provided to partners at the USDA-Natural Resources Conservation Service during an extreme weather event that created conditions for the failure of five dams in southwest Wisconsin. The data collected from these sites include soil samples, photographs, and field notes. Several of the structures failed along the intersection of the dam and the natural landscape, so the data can be used for future case studies for evaluating enhanced of the WinDAM model. In addition, researchers and their collaborators compiled technical guidance documents, information, and case studies to test the internal erosion feature of the computer code. Scientists in collaboration with the international research and engineering consulting communities, other Federal agency scientists and engineers, and academicians are continuing testing the internal erosion component of the model to compare with other available models to validate the model and examine the sensitivity of input parameters on model results.
For Objective 2, a researcher at Stillwater, Oklahoma, continued the development of engineering design guidance as it relates to the performance of stepped spillways with varying chute slopes and converging training walls, stilling basin designs, and step geometries. In addition, a stepped chute was examined to determine the influence of flow obstructions (e.g., bridge piers) across the spillway entrance. The researcher along with their cooperators completed a draft of the Stepped Spillway Design Chapter for the United States Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) National Engineering Handbook.
Accomplishments
1. Bevel-shaped stepped spillway design provides significant cost-savings. Roller compacted concrete (RCC) stepped spillways are frequently used to upgrade aging earthen dams. The construction industry explores new ways to more efficiently construct dams to provide a cost-savings to the end-user. As a result, design engineers consider whether these new construction techniques will keep the integrity of the spillway intact and safe. Changing the step geometry from a traditional shaped step to a bevel-shaped stepped was proven by ARS scientists at Stillwater, Oklahoma, as an alternative design and construction method for placing stepped spillways. Engineering consultants anticipate a cost-savings of thousands of dollars by incorporating this geometry change in their design. Federal agencies like the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) and the U.S. Army Corps of Engineers and engineering consultants worldwide have adopted this design alternative for extending the planned service life of embankment dams, so they can preserve the $2.4 billion in annual benefits of flood control, rural and municipal water supplies for economic growth, water for crop and energy production, healthy ecosystems, and recreation and tourism.
