Climate Change Investigation of Swat River Using HEC-HMS Hydrological Model

Abstract

Abstract: Pakistan is included in the most water stressed countries in the world and its water resources are vulnerably affected by the climate change. Monitoring regional watershed can help to secure resources for upcoming future. Our research is based on understanding of hydro- climatic regime of Swat River basin up to Khawaza Khela using physical based HEC-HMS model. The Model was calibrated and validated on daily scale and evaluated using statistical performance indicator to able to provide desired performance range. The calibration and validation of Nash-Sutcliff Coefficient were recorded 0.84 and 0.81, the Root Mean Square Error (RMSE) were recorded as 5.5 and 2.8, and the coefficient of determination (R2 ) results in 0.86 and 0.84 respectively. Furthermore, for climate change analysis two scenario: Representative Concentration Pathway (RCP) 4.5 and RCP8.5 of MIROC5 hydrological model were investigated and both the scenarios were incorporated into the selected model for future use, which showed increase in precipitation for both RCPs. At the end of century total annual rise of +195mm (14.8%) was observed for RCP8.5 and 119mm (9%) was observed for RCP4.5. On seasonal basis winter precipitation seems to grow over the century and other seasons remain slightly random. Analysis of river flow seems to predict higher magnitudes of flow. Likewise, at the end of century, RCP4.5 suggest 38.9% increase in flows and RCP8.5 showed 40.9% increase in flow. Seasonal analysis reveals that highest positive deviations were recorded during the season of monsoon and autumns for stream flow.