Climate change projections of continental-scale streamflow across the Mississippi River Basin

Abstract

A large body of scientific research has demonstrated a changing climate, which affects river flow regimes and extreme flood frequencies and magnitudes. The magnitude and frequency of extreme events are of critical importance in the evaluation of river systems to inform flood risk reduction under current and future conditions. The global climate projections from the Coupled Model Intercomparison Project, Phase 5 (CMIP5) datasets were used by the Variable Infiltration Capacity (VIC) land surface model to produce a runoff dataset, implementing a Bias-Correction Spatial Disaggregation (BCSD) approach. The resulting runoff was then used as input to the Routing Application for Parallel computatIon of Discharge (RAPID) river routing model to simulate daily flows within all 1.2 million Mississippi River Basin river reaches for years 1950 through 2099. This research effort analyzed the performance of the models for the historical time period, comparing with the observations at 64 gage locations for 16 different climate models. A recurrence interval analysis was performed to determine the 2-, 5-, 10-, 50-, 100-, 500-, and 1000-year events within both the historical and projected time periods, highlighting the relative changes predicted into the future. Anticipated seasonal changes are demonstrated by comparing monthly average streamflows for three different time periods (1951–2005, 2006–2049, and 2050–2099). Results indicate that the hydrologic conditions of the Lower Mississippi River are not stationary. Based on all 16 models considered in this study, the median of the model projections shows an 8% increase in the 100-year return period discharge at Vicksburg, Mississippi, into the future time period, although the full range of 16 models varies widely from − 11 to + 85% change in the 100-year discharge in the future.

Competing Influences of Land Use and Greenhouse Gas Emissions on Mississippi River Basin Hydroclimate Simulated Over the Last Millennium

“…In closing, climate change has and will continue to alter the MRB's flow regimes as well as the magnitude and frequency of extreme flooding events in the MRB (Lewis et al., 2023). Understanding how naturally occurring variations in the climate system, in addition to anthropogenic activity, independently influence climate change can help mitigate future risk in the 21st century.…”

“…A warmer atmosphere drives an increase in water vapor and extreme precipitation due to the Clausius-Clapeyron relationship (Held & Soden, 2006;Ivancic & Shaw, 2016), but alongside the increase in temperature, there will be less precipitation falling as snow. Changes in both greenhouse gas concentrations (GHG) and land use/land cover (LULC) have demonstrable impacts on the Mississippi's flood regime, but debate remains surrounding the dominance of each on runoff, and surrounding their impacts on the magnitude and frequency of extreme flooding events in the MRB (Foley et al, 2004;Frans et al, 2013;Jha et al, 2004;Lewis et al, 2023;Mishra et al, 2010;Pinter et al, 2008;Qian et al, 2007;Rossi et al, 2009;Schilling et al, 2008Schilling et al, , 2010Tran & O'Neill, 2013). Natural variability also influences trends in precipitation (Eischeid et al, 2023) and runoff (Hoell et al, 2023) in ways that are different from what might be expected from LULC changes alone.…”