Since 2011, the U.S. Army Corps of Engineers (USACE) Civil Works Strategic Plan has stressed sustainable solutions for the 21st century. For our reservoirs, this requires that we take into account all of the factors that impact their performance and reliability. Evaluating reservoir vulnerabilities to changes in sedimentation rates is critical to the long-term management and reliable performance of reservoirs. USACE adaptation pilots identified altered reservoir sedimentation rates that result from a changing climate and land use change as a critical area for agency missions and operations.

USACE is the largest operator of dams in the United States. Each USACE dam was planned, designed and built to provide specific benefits to the American public, including navigation, flood risk reduction, hydropower generation, recreation, and water supply. Most of the USACE dams have operated for more than 50 years, with some approaching 100 years of operation. Climate change has been identified as a major cause of vulnerability due to its role in changing hydrologic and sedimentation patterns.

Uncertainty about sediment conditions is exacerbated where budget constraints have limited periodic sediment surveys and studies to evaluate the effects of these changes through standard operations and maintenance (O&M) budgets. Therefore, it is essential that we establish baseline information on reservoir sediment levels and remaining storage capacity, and then determine how future global and climate changes will impact sedimentation.

This interdisciplinary and interagency project team utilizes USACE regional technical specialists and the USACE Committee on Channel Stabilization to build knowledge and capacity within USACE. The team's activities include:

• assessing existing knowledge about USACE sedimentation;
• reviewing and updating existing methods and policies to support updated sediment data collection and studies;
• developing a strategy to update reservoir sedimentation information
• prioritizing needs;
• conducting reservoir sedimentation studies according to the priorities established.

Compiling Reservoir Sediment Data

This project's objective is to enhance reservoir storage information and improve climate preparedness and resilience at USACE reservoirs. To date, we have developed a central web-based database and portal that contains reservoir sediment surveys and associated information with other databases (e.g., National Inventory of Dams, Corps Water Management System, and Drought Contingency Update Portal) to leverage existing information and maximize knowledge related to reservoir sedimentation and associated impacts. We have created business intelligence dashboards allowing users to analyze and visualize data, including overview information on reservoir sediment status and volume loss by reservoir zone.

The team is coordinating with other Federal agencies (e.g., US Geological Survey (USGS), Bureau of Reclamation) are also collecting sedimentation information. This project supports the USGS-operated interagency Reservoir Sedimentation Database (RESSED) by enabling bulk loading of USACE reservoir sedimentation data into the database.

USACE has developed a baseline report on USACE reservoir sedimentation status and projected climate change impacts to reservoirs. As part of an effort to set a reservoir sediment baseline, six USACE districts were selected as a representative sample of districts that manage reservoirs in a variety of environmental settings. Subsequently, a web portal was developed to collect and house reservoir sediment information from across the Nation and to provide analytical information that supports efficient and sustainable reservoir sediment management. This effort is also producing climate-impacted reservoir sediment indicators to support analysis of future sedimentation rates and how they are changing with observed and projected climate changes for use in Watershed Screening Level Climate Vulnerability Analysis Tool.

USACE Reservoir Sedimentation in the Context of Climate Change (pdf, 5.55 MB) summarizes the findings of the six pilot districts and the additional information housed in the new web portal. It provides recommendations on how to best achieve planned reductions in existing data gaps and how to identify the minimum survey frequency required to accurately project sedimentation impacts to reservoir project benefits.

For more information, see the Reservoir Sediment Fact Sheet (pdf, 721 KB) or USACE Reservoir Sedimentation in the Context of Climate Change (pdf, 5.55 MB).

Reservoir Surveys for Drought-Impacted Reservoirs

Drought results in much lower than normal reservoir pools, revealing sedimentation that could adversely impact storage. USACE needed a low-cost and efficient method to collect data on the exposed bathymetry (the measurement of water depth at various places in the reservoir pools and the information derived from those measurements). This project provides precise, high-resolution data for estimating sedimentation rates for these reservoirs. Rapid deployment of Airborne Laser Scanning (ALS) systems, including custom designed hardware that easily transfers between various aircraft platforms, and processing and dissemination of data within the Geospatial Repository and Data Management System (GRiD), was tested in California during the 2015 drought to refine the data acquisition process, modify the system for specific aircraft, and evaluate post-processing requirements.

For more information, see USACE LiDar Capabilities for Reservoir Sedimentation (pdf, 478 KB).

National Drought Resilience: Improved Reservoir Sediment Surveys (pdf, 5.34 MB) addresses work undertaken by the U.S. Army Corps of Engineers (USACE) and Department of the Interior's Bureau of Reclamation (Reclamation), to support the National Drought Resilience Partnership (NDRP). The report focuses on NDRP Goal 1, Action 4: Encourage Federal Reservoir Surveys.

The primary objective of the report was to take advantage of drought-induced low reservoir levels to increase knowledge of the state of reservoir sedimentation, which in turn affects reservoir storage. An interagency team developed a strategy and supporting technologies to enable rapid deployment and data collection using Light Detection and Ranging (LiDAR) technology. Droughts tend to be regional phenomena; multiple reservoirs in an affected area are likely to be at exceptionally low water levels. This enables economies of scale through collection of data at multiple reservoirs during a single LiDAR mission.

For more information, see National Drought Resilience: Improved Reservoir Sediment Surveys (pdf, 5.34 MB)