H196-0006
Analyzing the Effect of Climate Change on Extreme Flood Events in the Mississippi River Basin
Analyzing the Effect of Climate Change on Extreme Flood Events in the Mississippi River Basin
Wednesday, 16 December 2020
Poster
Abstract:
A large body of scientific research has demonstrated that the changing climate may affect river flow regimes and intensify extreme flood frequencies and magnitudes. This research analyzes the recurrence intervals of extreme flow events under the projected climate conditions for the entire Mississippi River Basin (MRB), the United States’ largest watershed, covering 41% of the contiguous United States (CONUS). Due to the large area of the MRB, expected changes across the basin may vary significantly, and careful analysis is necessary to make accurate predictions of discharge across gage locations.
Our previous work on future MRB streamflows was completed using the statistically downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) projections under the representative concentration pathway (RCP) 4.5 emission scenario. These projections were used to drive a CONUS Variable Infiltration Capacity (VIC) model at 12km spatial resolution. The simulated runoff was then used as input to drive the Routing Application for Parallel computatIon of Discharge (RAPID) river routing model to simulate daily flows within all 1.2 million MRB river reaches for historical and projected time periods (1950-2099). This initial research has suggested significant change of discharge values across critical areas of the MRB.
To further understand how different variables (e.g., emission scenario, downscaling approach, hydrologic model resolution) affect the statistics of future MRB extreme flood events, we utilized a different high-resolution future hydroclimate dataset in this study. This dataset includes ten CMIP5 GCMs, dynamically downscaled using the RegCM4 regional climate model, under the RCP 8.5 high emission scenario. The bias-corrected RegCM4 output was used to drive a version of the CONUS VIC model at 4km spatial resolution. The resulting runoff was driven by the same RAPID river routing model to simulate daily flows across multiple model ensembles. The change of recurrence intervals is then estimated and compared with historical flow observations across gages. By using a different future hydroclimate dataset, our goal is to understand how different the statistics of future MRB extreme flood events may be changed, which help us identify research priorities and determine next steps.
Our previous work on future MRB streamflows was completed using the statistically downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) projections under the representative concentration pathway (RCP) 4.5 emission scenario. These projections were used to drive a CONUS Variable Infiltration Capacity (VIC) model at 12km spatial resolution. The simulated runoff was then used as input to drive the Routing Application for Parallel computatIon of Discharge (RAPID) river routing model to simulate daily flows within all 1.2 million MRB river reaches for historical and projected time periods (1950-2099). This initial research has suggested significant change of discharge values across critical areas of the MRB.
To further understand how different variables (e.g., emission scenario, downscaling approach, hydrologic model resolution) affect the statistics of future MRB extreme flood events, we utilized a different high-resolution future hydroclimate dataset in this study. This dataset includes ten CMIP5 GCMs, dynamically downscaled using the RegCM4 regional climate model, under the RCP 8.5 high emission scenario. The bias-corrected RegCM4 output was used to drive a version of the CONUS VIC model at 4km spatial resolution. The resulting runoff was driven by the same RAPID river routing model to simulate daily flows across multiple model ensembles. The change of recurrence intervals is then estimated and compared with historical flow observations across gages. By using a different future hydroclimate dataset, our goal is to understand how different the statistics of future MRB extreme flood events may be changed, which help us identify research priorities and determine next steps.