Analyzing Future Flooding under Climate Change Scenario using CMIP5 Streamflow Data

Flooding is the most severe and costlier natural hazard in US. The effect of climate change has intensified the scenario in recent years. Flood prevention practice along with proper understanding of flooding event can mitigate the risk of such hazard. The flood plain mapping is one of the technique to quantify the severity of the flooding. Carson City, which is one of the agricultural area in the desert of Nevada has experienced peak flood in recent year. The underlying probability distribution for the area, latest Coupled Model Intercomparison Project (CMIP5) streamflow data of Carson River were analyzed for 27 different statistical distributions. The best fitted distribution underlying was used to forecast the 100yr flood (design flood). The data from 1950-2099 derived from 31 model and total 97 projections were used to predict the future streamflow. Delta change method is adopted to quantify the amount of future (2050-2099) flood. To determine the extent of flooding 3 scenarios (i) historic design flood, (ii) 500yr flood and (iii) future 100yr flood were routed on a HEC-RAS model, prepared using available terrain data. Some of the climate projection shows extreme increase in future design flood. The future design flood could be more than the historic 500yr flood. At the same time, the extent of flooding could go beyond the historic flood of 0.2% annual probability. This study suggests an approach to quantify the future flood and floodplain using climate model projections. The study would provide helpful information to the facility manager, design engineer and stake holders.