Search for: All records

Low-head dams (LHDs) are widespread in river systems, yet the volume of sediment impounded behind them remains largely unquantified. Failure or planned removal of these often-aging structures can mobilize stored sediment, posing added risk to reservoirs already losing capacity to sedimentation. In Kansas, the failure of an LHD in May 2018 released sediment equivalent to ~25% of the downstream reservoir's annual accumulation and motivated a broader assessment of storage behind other LHDs. Addressing this knowledge gap, this study quantifies sediment storage behind LHDs located upstream of three federal reservoirs: Tuttle Creek Lake, Perry Lake, and Kanopolis Lake. An integrated approach was employed, combining remote sensing for LHD identification with field-based bathymetric surveys and sediment analysis to directly measure accumulated sediment volumes (VLHD) at representative sites and to estimate VLHD at remotely sensed sites. The relative storage for individual LHDs, expressed as a fraction of downstream annual reservoir sedimentation (fARS), ranged from 0.005 to 0.659, with a median fARS of 0.025. Storage volume (VLHD) was more closely related to local physical properties of LHDs—such as dam height and width—than watershed-scale drivers, such as precipitation and drainage area. Bathymetric maps revealed scour holes immediately upstream of LHDs, typically centered 20–50 m upstream and up to ~1.3 m deep, indicating partial sediment continuity and dynamic equilibrium. This research provides crucial data to inform regional sediment management and enhance reservoir sustainability in Kansas and offers a transferable methodology for quantifying the contribution of LHDs in other watersheds.