An examination of the potential wetland development landscape around managed reservoirs in the central U.S. Great Plains

Reservoirs around the world are losing storage capacity due to sediment infilling, leading to reductions in the quality and value of reservoir uses. However, the sediment accumulating in the upper ends of reservoirs, particularly around primary inflows within well-defined floodplains, could potentially be developing into wetland ecosystems that provide services such as sediment filtration, nutrient sequestration, and wildlife habitat. In this study, we examine lake level, wetland, and topographic characteristics for 20 large, federally operated reservoirs in the state of Kansas located in the central U.S. Great Plains. First, daily water level data and empty-basin topography (created by merging LiDAR elevation with bathymetry) are used to delineate the primary fluctuation zone for each reservoir, which we define to be the range of extents between the 25th and 75th lake level percentiles. Next, we use data from the U.S. Fish and Wildlife Service National Wetlands Inventory (NWI) to characterize wetland composition in the upper fluctuation zone (extent range between the 50th and 75th lake level percentiles) and the upper flood pool (extent range between the 75th percentile and the maximum designed flood pool elevation). For the final assessment, we examine the relationship between ground slope and NWI in the upper fluctuation zone and the upper flood pool. Results indicate that relatively low-sloped ground is classified as wetland in the upper fluctuation zone at 24% greater frequency than in the upper flood pool.