Climate change impacts on floodway and floodway fringe: a case study in Shahrchay River Basin, Iran

This study evaluates the impacts of climate change on the floodway and floodway fringe along the Shahrchi River located at Lake Urmia Basin, Iran. The raw historical (1971-2000) and near future (2021-2050) precipitation and temperature data were obtained from Middle East and North Africa domain of the Coordinated Regional Climate Downscaling Experiment (CORDEX). The projections from the global climate model were corrected using daily observations from in situ stations and then used as inputs for SWAT+ hydrological model to forecast daily streamflow under the representative concentration pathway 8.5 (RCP8.5) scenario at the near future period. Flood frequency analysis at each period was accomplished and floodway and floodway fringe were obtained through flood wave routing along the river and a multi-criteria decision-making approach, respectively. The results indicated that the climate model typically underestimates the temperature and precipitation values at the historical period and the future projections need to be adjusted. In addition, a significant decrease in total runoff volume in the future periods is expected; however, the hydrologic models showed that the number and magnitude of peak flows would be increased.