The Middle Mississippi River (MMR) and lower Missouri River (MOR) provide critical navigation waterways, ecological habitat, and flood conveyance. They are also directly linked to processes affecting geomorphic and ecological conditions in the lower MR and Delta. For this study, a method was developed to measure suspended‐sediment concentration (SSC) and turbidity along the MMR and the lower MOR using Landsat imagery. Data from nine United States Geological Survey water‐quality monitoring stations were used to create a model‐development dataset and a model‐validation dataset. Concurrent gaging data were identified for available Landsat images to generate the datasets. Surface‐reflectance filters were developed to eliminate images with cirrus cloud coverage or vessel traffic. Using the filtered model‐development dataset, unique reflectance‐SSC and reflectance‐turbidity models were developed for three Landsat sensors: Landsat 8 Operational Land Imager, Landsat 7 Enhanced Thematic Mapper Plus, and Landsat 4–5 Thematic Mapper. Coefficient of determination values for the models ranged from 0.72 to 0.88 for the model‐development dataset. The model‐validation dataset was used to evaluate the performance of the models and had coefficient of determination values ranging from 0.62 to 0.79.

The US Army Engineer District, San Francisco (SPN) and the Coastal Inlets Research Program conducted a pilot study to consider various placement locations for dredged material in vicinity of Noyo Harbor, CA. Approximately 30,000-40,000 cu yd/yr of beach-quality sediment is dredged from the navigation channel and the lower Noyo River, located on the north central California coast. The pilot study investigated several potential locations for placement of dredged sediments in one of two areas north of Noyo Bay. The investigation included field data collection and numerical modeling of near-field sediment transport and suspended sediment concentration during and after placement of the dredged sediments under combined wave and current conditions. The numerical model provided the technical information necessary for SPN and Noyo Harbor stakeholders to evaluate a location site that is economically feasible for the optimum sediment placement. Upon acceptance by the stakeholders and receipt of additional funds, a demonstration project will be conducted, and the Dredged Material Management Plan (DMMP) for Noyo Harbor will be updated to include a beneficial use site for nearshore placement.

The U.S. Army Corps of Engineers (USACE) San Francisco District (SPN) and Coastal Inlets Research Program (CIRP) are presently performing hydrodynamics, wave, and sediment transport numerical modeling study with the Coastal Modeling System (CMS) to evaluate a designated dredged-material placement site nearshore the beach erosion hot spot and onshore nourishment alternatives on Ocean Beach, California. Both model results and measurements reveal that tidal forcing is the main process in the nearshore area where the tidal current is predominantly along the shoreline. The calculated sediment transport shows more longshore movement than cross-shore shoreward the dredgedmaterial placement site. The model result also indicates significant sediment erosion at Ocean Beach.

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