Recommended Data Collection to Optimize Beneficial Reuse of Dredged Material: A Sediment Budget for the Savannah River Harbor

Decades-long calls for nature-based approaches to coastal flood risk mitigation have increased the demand for beneficial use of dredged material (BUDM). However, coastal management authorities often lack data and tools required to accurately forecast lifecycle management planning of BUDM projects. One particular obstacle to scaling up BUDM is inadequate data for regional sediment availability. Sediment budgeting and regional sediment management plans have been proposed as tools to address this shortcoming. Using dredge records and a suite of riverine and coastal sediment data, this study calculated the annual availability of sediment for BUDM in the Savannah Harbor region. However, serious shortcomings in available data and/or reporting were identified. We hypothesize that dredging volumes determined from pre- and postdredging bathymetric surveys are substantially larger than the actual volume removed from the system. Although the study concluded that a substantial quantity of sediment is made available by Savannah River dredging for nature-based projects, uncertainty currently exists about exactly how much. Several suggestions for improvement are prescribed to aid future sediment budgeting efforts and, ultimately, BUDM project planning. Additional channel sediment grain size and bulk density measurements, updated total suspended sediment measurements for the Savannah River, regular LiDAR runs covering the channel banks and dredge material containment areas, and channel-wide bathymetry taken at consistent time intervals were identified as important data needs for matching sediment quantity and quality with local BUDM requirements. Regional marsh and beach assessments to determine current and future BUDM needs are also identified as an important tool for matching dredged volumes with potential uses.