12 May 2021

Wintertime Snow and Precipitation Conditions in the Willow Creek Watershed above Ririe Dam, Idaho

ABSTRACT:  The Ririe Dam and Reservoir project is located on Willow Creek near Idaho Falls, Idaho, and is important for flood risk reduction and water supply. The current operating criteria is based on fully storing a large winter runoff event. These winter runoff events are generally from large storm events, termed atmospheric rivers, which produce substantial precipitation. In addition to the precipitation, enhanced runoff is produced due to frozen soil and snowmelt. However, the need for additional water supply by local stakeholders has prompted the U.S. Army Corps of Engineers to seek to better understand the current level of flood risk reduction provided by Ririe Dam and Reservoir.  Flood risk analysis using hydrologic modeling software requires quantification of the probability for all of the hydrometeorologic inputs. Our study develops the precipitation, SWE, and frozen ground probabilities that are required for the hydrologic modeling necessary to quantify the current winter flood risk.

12 May 2021

Automated Characterization of Ridge-Swale Patterns Along the Mississippi River

Abstract: The orientation of constructed levee embankments relative to alluvial swales is a useful measure for identifying regions susceptible to backward erosion piping (BEP). This research was conducted to create an automated, efficient process to classify patterns and orientations of swales within the Lower Mississippi Valley (LMV) to support levee risk assessments. Two machine learning algorithms are used to train the classification models: a convolutional neural network and a U-net. The resulting workflow can identify linear topographic features but is unable to reliably differentiate swales from other features, such as the levee structure and riverbanks. Further tuning of training data or manual identification of regions of interest could yield significantly better results. The workflow also provides an orientation to each linear feature to support subsequent analyses of position relative to levee alignments. While the individual models fall short of immediate applicability, the procedure provides a feasible, automated scheme to assist in swale classification and characterization within mature alluvial valley systems similar to LMV.

14 Oct 2020

Red River Structure Physical Model Study

Abstract: A proposed Red River Structure (RRS), intended to function as one of three gated structures comprising the Fargo-Moorhead Metropolitan Area Flood Risk Management Project, was tested in a general physical model. A 1:40 Froude-scale was applied to model the structure, engineered channels, existing bathymetry/topography in the Red River and overbank areas, and the proposed Southern Embankment. The physical model was used to ensure that the RRS could pass at least 104,300 cfs during the Probable Maximum Flood while maintaining a maximum pool water surface elevation of 923.5 ft. The physical model was also utilized to optimize the approach structure, stilling basin, retaining walls, and erosion protection designs. The physical modeling effort resulted in an optimized stilling basin wall, retaining wall, and end sill geometry/configuration where erosive conditions were not observed outside and adjacent to the stilling basin. Properly designed riprap (St. Paul District’s R470 gradation) proved to be successful in protecting the proposed RRS from potential scour downstream. The modified approach wall design proved to be successful in creating safe approach flow conditions as well as acceptable flow separation patterns. It is recommended that Alternative 3 be the design used going forward.

17 Jun 2020

PUBLICATION NOTICE: Development and Application of the CASM-SL to Support Nutrient Management in Potential Sangamon River Levee Setbacks

Abstract: Levee setbacks are defined by the intentional relocation of levees away from the river bank. This placement is often done to reduce flood risk, but it can also have environmental benefits. The Comprehensive Aquatic System Model (CASM) was used to look at the potential fate of nutrients and several environmental benefits for five potential management scenarios along the lower Sangamon River in Illinois. The model results showed that two scenarios were much more environmentally favorable relative to the outcomes considered here. One of the scenarios, where the existing gates were operated to allow the river access to the area behind the levee during extreme floods, was better at nitrogen and phosphorous accumulation. Removing the gates and creating a levee setback at this same site produced more aquatic plants, invertebrates, and fish but was not as effective at nutrient accumulation. This application of CASM demonstrates the potential of the model to provide objective rankings for the environmental benefits of levee setbacks.

22 Apr 2020

PUBLICATION NOTICE: Operation and Deployment Risk Assessment Report for the City of Cedar Rapids, Iowa: Alternative and Sequencing Optimization for Removable Flood Barriers

ABSTRACT: The City of Cedar Rapids, Iowa, partnered with engineering firms and the US Army Engineer District, Rock Island (MVR), to develop a Flood Control System (FCS). In 2011, the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (ERDC-CHL), was tasked with completing a risk assessment of removable floodwalls on the eastern side of the Cedar River. In 2016, ERDC-CHL was asked to include the temporary flood closure barriers on both sides of the Cedar River. Phase 1 of the study consisted of seven alternatives to be considered for the final FCS design, with a goal of a 90% confidence of successful deployment. Phase 2, initiated by MVR, targeted a 95% confidence level. The method used for evaluation was RiskyProject® software. The software used a Monte Carlo method of analysis to determine a range of durations, manpower, and labor costs based on logical sequencing. The results showed that the “Master Plan Minus 400 ft” alternative to be the most efficient for Phase 1. The most efficient alternative for Phase 2 was Task 5.4, which achieved a 95% confidence level of completion within 48 hours. The Phase 1 and the Phase 2 descriptions are detailed within this report.

1 Apr 2020

PUBLICATION NOTICE: Comparison of Benthic Fish Assemblages along Revetted and Natural Banks in the Lower Mississippi River: A 30-Year Perspective

 Link: http://dx.doi.org/10.21079/11681/35259Report Number: MRG&P Report No. 29Title: Comparison of Benthic Fish Assemblages along Revetted and Natural Banks in the Lower Mississippi River: A 30-Year PerspectiveBy K. Jack Killgore and Steven G. GeorgeApproved for Public Release; Distribution is Unlimited January 2020Abstract: Benthic fish

22 Jan 2020

PUBLICATION NOTICE: Comparison of Benthic Fish Assemblages along Revetted and Natural Banks in the Lower Mississippi River: A 30-Year Perspective

 Link: http://dx.doi.org/10.21079/11681/35259 Report Number: MRG&P Report No. 29Title: Comparison of Benthic Fish Assemblages along Revetted and Natural Banks in the Lower Mississippi River: A 30-Year Perspective By K. Jack Killgore and Steven G. George Approved for Public Release; Distribution is Unlimited January 2020 Abstract: Benthic fish