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  • Backward Erosion Progression Rates from Small-Scale Flume Tests

    Abstract: Backward erosion piping (BEP) is an internal erosion mechanism by which erosion channels progress upstream, typically through cohesionless or highly erodible foundation materials of dams and levees. As one of the primary causes of embankment failures, usually during high pool events, the probability of BEP-induced failure is commonly evaluated by the U.S. Army Corps of Engineers for existing dams and levees. In current practice, BEP failure probability is quantitatively assessed assuming steady state conditions with qualitative adjustments for temporal aspects of the process. In cases with short-term hydraulic loads, the progression rate of the erosion pipe may control the failure probability such that more quantitative treatment of the temporal development of erosion is necessary to arrive at meaningful probabilities of failure. This report builds upon the current state of the practice by investigating BEP progression rates through a series of laboratory experiments. BEP progression rates were measured for nine uniform sands in a series of 55 small-scale flume tests. Results indicate that the pipe progression rates are proportional to the seepage velocity and can be predicted using equations recently proposed in the literature.
  • Sabine Pass to Galveston Bay, TX Pre-Construction, Engineering and Design (PED): Coastal Storm Surge and Wave Hazard Assessment: Report 1 – Background and Approach

    Abstract: The US Army Corps of Engineers, Galveston District, is executing the Sabine Pass to Galveston Bay Coastal Storm Risk Management (CSRM) project for Brazoria, Jefferson, and Orange Counties regions. The project is currently in the Pre-construction, Engineering, and Design phase. This report documents coastal storm water level and wave hazards for the Port Arthur CSRM structures. Coastal storm water level (SWL) and wave loading and overtopping are quantified using high-fidelity hydrodynamic modeling and stochastic simulations. The CSTORM coupled water level and wave modeling system simulated 195 synthetic tropical storms on three relative sea level change scenarios for with- and without-project meshes. Annual exceedance probability (AEP) mean values were reported for the range of 0.2 to 0.001 for peak SWL and wave height (Hm0) along with associated confidence limits. Wave period and mean wave direction associated with Hm0 were also computed. A response-based stochastic simulation approach is applied to compute AEP runup and overtopping for levees and overtopping, nappe geometry, and combined hydrostatic and hydrodynamic fluid pressures for floodwalls. CSRM structure crest design elevations are defined based on overtopping rates corresponding to incipient damage. Survivability and resilience are evaluated. A system-wide hazard level assessment was conducted to establish final recommended system-wide CSRM structure elevations.
  • Winter Gavins Point releases will be at minimum rates

    Updated: Fort Peck release reductions was incorrectly reported as Sept 6 and has been corrected to Sept. 16. Drought conditions, particularly in the Missouri River Basin above Sioux City, Iowa (upper Basin), are persisting. Per the Master Manual and the Sept. 1 System storage check, winter releases from Gavins Point Dam will be 12,000 cubic feet per second, as part of the overall water conservation measures. “Reservoir inflows in August were much lower than average. We expect below-average inflows into the System through the rest of 2021,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.
  • Army Corps to draw down reservoirs at Francis E. Walter Dam and Blue Marsh Lake in advance of Hurricane Ida

    The U.S. Army Corps Engineers Philadelphia District has announced it will draw down the reservoirs at Blue Marsh Lake and Francis E. Walter Dam in preparation for significant forecasted rainfall associated with Hurricane Ida. Blue Marsh Lake is located on the Tulpehocken Creek, a tributary of the Schuylkill River, about four miles northwest of Reading, Pa. Francis E. Walter Dam is located at the confluence of the Lehigh River and Bear Creek in Luzerne and Carbon Counties, Pa.
  • Expert Elicitation Workshop for Planning Wetland and Reef Natural and Nature-Based Features (NNBF) Futures

    Abstract: This special report discusses the outcomes of a September 2019 workshop intended to identify barriers to the consideration and implementation of natural and nature-based features (NNBF) in US Army Corps of Engineers (USACE) civil works projects. A total of 23 participants representing seven USACE districts, the US Army Engineer Research and Development Center (ERDC), and the University of California–Santa Cruz met at USACE’s South Atlantic Division Headquarters in Atlanta, Georgia, to discuss how to facilitate the implementation of NNBF into USACE project planning for wetlands and reefs using six categories: (1) site characterization, (2) engineering and design analysis, (3) life-cycle analysis, (4) economic analysis, (5) construction analysis, (6) and operation and maintenance (and monitoring). The workshop identified seven future directions in wetland and reef NNBF research and development: • Synthesize existing literature and analysis of existing projects to better define failure modes. • Determine trigger points that lead to loss of feature function. • Identify performance factors with respect to coastal storm risk management (CSRM) performance as well as ecological performance. • Focus additional research into cobenefits of NNBF. • Quantify the economic life-cycle costs of a project. • Improve technology transfer with regards to NNBF research and topics.
  • Geotechnical Inspection and Technical Review of Santa Margarita River Marine Corps Air Station Levee, U.S. Marine Corps, Camp Pendleton, CA, 19-20 November 2019

    Abstract: This report describes activities performed, results obtained, and conclusions made from an independent technical review of past levee inspections and the proposed remediation plan for the Santa Margarita Levee that surrounds the U.S. Marine Corps Air Station (MCAS) Camp Pendleton. In support of the technical review, ERDC personnel performed a supplemental levee inspection on 19 and 20 November 2019 with MCAS personnel. Previous levee inspections had rated the levee system as Unacceptable due to unwanted vegetation encroaching on the levee right-of-way, which prevents full inspection during flooding. Concerns were raised by the U.S. Fish and Wildlife (USFW) about environmental impacts of the proposed remediation measures and the necessity of such actions. USFW personnel requested an engineering review from an independent party, and ERDC was tasked with performing the independent technical review. The following special report describes the tasks performed and results obtained from the independent technical review.
  • Rapid Tidal Reconstruction with UTide and the ADCIRC Tidal Database

    Abstract: The quantification of storm surge is vital for flood hazard assessment in communities affected by coastal storms. The astronomical tide is an integral component of the total still water level needed for accurate storm surge estimates. Coastal hazard analysis methods, such as the Coastal Hazards System and the StormSim Coastal Hazards Rapid Prediction System, require thousands of hydrodynamic and wave simulations that are computationally expensive. In some regions, the inclusion of astronomical tides is neglected in the hydrodynamics and tides are instead incorporated within the probabilistic framework. There is a need for a rapid, reliable, and accurate tide prediction methodology to provide spatially dense reconstructed or predicted tidal time series for historical, synthetic, and forecasted hurricane scenarios. A methodology is proposed to combine the tidal harmonic information from the spatially dense Advanced Circulation hydrodynamic model tidal database with a rapid tidal reconstruction and prediction program. In this study, the Unified Tidal Analysis program was paired with results from the tidal database. This methodology will produce reconstructed (i.e., historical) and predicted tidal heights for coastal locations along the United States eastern seaboard and beyond and will contribute to the determination of accurate still water levels in coastal hazard analysis methods.
  • Drought conditions persist in the upper Missouri River Basin

    Drought conditions continue to impact the upper Missouri River Basin above Sioux City, Iowa (upper Basin). July runoff in the upper Basin was 34% of average. July runoff above Fort Peck Dam was the lowest in 123 years of record-keeping. The updated 2021 upper Basin runoff forecast is 14.6 million acre-feet (MAF), 57% of average. If realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on August 1 was 53.9 MAF, 2.2 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.
  • Mississippi River Commission cancels Upper Mississippi River portion of low water inspection trip but still plans to conduct Lower Mississippi River portion

    Due to the rising cases of COVID, the Mississippi River Commission (MRC) has canceled the Upper Mississippi River portion of its annual low water inspection trip on board the Motor Vessel MISSISSIPPI, which was scheduled for August 15-20, 2021. The health and safety for people is a priority during this critical time in our nation. The MRC still intends to conduct the Lower Mississippi River portion of the low water inspection trip and public hearings scheduled for August 22-27, 2021. Four public meetings have been scheduled aboard the Motor Vessel MISSISSIPPI in select towns along the river.
  • USACE implements drought conservation measures

    Water conservation measures were enacted for the second half of the navigation flow support season based on the July 1 Missouri River Mainstem Reservoir System storage, per the guidelines outlined in the Master Manual. Very dry conditions continue to impact the upper Missouri River Basin above Sioux City, IA (upper Basin) despite recent heavy rainfall in the lower Basin. As a result of the low precipitation and widespread drought conditions, June runoff in the upper Basin was 52% of average. The updated 2021 upper Basin runoff forecast is 15.6 million acre-feet (MAF), 60% of average. If realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on July 1 was 55.2 MAF, 0.9 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.