Modeling Future Sediment Transport Variations at a Watershed-Scale Using Landlab: A Preliminary Example from the Chestatee River in Northern Georgia, USA.

Christopher Sheehan, Boston College Department of Earth and Environmental Sciences Chestnut Hill Massachusetts, United States. sheehacz@bc.edu

Mark Behn, Boston College Department of Earth and Environmental Sciences Chestnut Hill Massachusetts, United States.

Noah Snyder, Boston College Department of Earth and Environmental Sciences Chestnut Hill Massachusetts, United States.

Travis Dahl, U.S. Army Engineer Research & Development Center Vicksburg Mississippi, United States.

During the 21st century, anthropogenically modulated changes in climate and land cover will drive variations in sediment dynamics throughout rivers, reservoirs, and coastlines. These changes threaten the integrity of dams, levees, and riparian ecosystems, necessitating strategies to help mitigate their associated hazards and to detect and prevent adverse consequences of engineering solutions. To optimize these strategies, geomorphologists require calibrated, watershed-scale numerical simulations of sediment transport that can predict how fluvial networks will respond to different forcings throughout their catchments. We aim to develop watershed-scale landscape evolution models of several U.S. rivers to explore how climate and land-use change over the coming decades to centuries will influence sediment delivery to reservoirs, locks, harbors, and coasts. The models will be calibrated by historical sediment flux data, allowing them to predict how the fluvial systems will respond to plausible scenarios of future climatic and anthropogenic forcings. The Chattahoochee River in the southeastern U.S. is an ideal catchment to begin this work due to its recent urban development and sedimentation records near its outlet at Lake Seminole. We devise procedures for processing USGS NHDPlus HR datasets (Moore et al., 2019) at the HU4 and HU8 scale for compatibility with the fluvial process components of Landlab (Hobley et al., 2017; Barnhard et al., 2020). Using NLCD land cover products (Wickham et al., 2021), NRI erosion rate estimates (USDA, 2020), and historical streamflow and sediment load data (USGS, 2021), we will leverage Landlab to construct models of the Chattahoochee catchment and test their ability to replicate sedimentation records at Lake Seminole. Here, we present preliminary results obtained by applying these procedures to the Chestatee branch of the Chattahoochee River and its outlet at Lake Lanier in northern Georgia. Future versions of this workflow will use a range of projected 21st century precipitation and land cover changes to predict potential variations in future sediment generation, transport, and storage throughout the Chattahoochee watershed and other U.S. rivers.

2022 CSDMS meeting-033

Modeling Future Sediment Transport Variations at a Watershed-Scale Using Landlab: A Preliminary Example from the Chestatee River in Northern Georgia, USA.