10 May 2021

Modeling the Effect of Increased Sediment Loading on Bed Elevations of the Lower Missouri River

Purpose: This US Army Corps of Engineers (USACE) National Regional Sediment Management Technical Note (RSM-TN) documents the effects of increased sediment loading to the Missouri River on bed elevations in the lower 498 miles. This was accomplished using a one-dimensional (1D) HEC-RAS 5.0.7 sediment model.

1 Oct 2020

Physical Factors That Influence Muddy Bed Aggregate Production, Size, and Durability

Abstract: Aggregation state significantly influences the transport characteristics of fine sediments. While research has documented the presence of mud aggregates in multiple coastal and estuarine environments, bed aggregates are largely absent from numerical models used to predict cohesive sediment transport. The U.S. Army Corps of Engineers (USACE) is conducting studies to evaluate the impact muddy bed aggregates have on sediment management issues, and how to account for aggregates in numerical models. In this study, physical properties associated with cohesive behavior were evaluated to determine if they could be used as predictors for bed aggregate production, size, and durability. Results showed that aggregates were consistently produced in cohesive sediments, and that median aggregate size was ~10-450x larger than the disaggregated sediment. Clay content had strong correlation with relative aggregate size, though statistically significant correlations were also found with sand content, water content, and density. Durability testing indicated that aggregate break-up followed exponential models, and that in limited instances, rates of break-up correlated with organic content.

20 Apr 2020

PUBLICATION NOTICE: Bed-Load Transport Measurements on the Chippewa River Using the ISSDOTv2 Method

PURPOSE: This Regional Sediment Management (RSM) Technical Note (TN) provides information on bed-load measurements obtained on the Chippewa River, Wisconsin, in the spring of 2018. The ISSDOTv2 method was developed by the U.S. Army Corps of Engineers (USACE), Engineering Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), River and Estuarine Engineering Branch. The method uses time-sequenced bathymetric data to determine a bed-load transport rate. When transport rates are obtained with concurrent flow-rate data, it is possible to develop bed-load rating curves. Such rating curves are extremely valuable in forecasting or hindcasting bed-load sediment delivery for the location at which the data were obtained. This is very important for river managers in developing sediment budgets and in the planning of dredging operations.  In the present study, the USACE Mississippi Valley Division (MVD), St. Paul District (MVP), had contracted with the U.S. Geological Survey (USGS) for real-time monitoring of suspended-sediment concentrations (suspended sand load and bed-load sediment) on the lower Chippewa River, a major source and contributor of sand-sized sediment to the Upper Mississippi River (UMR). The bed-load values obtained using ISSDOTv2 are presented in this RSM TN.