Climate change impact on flow discharge of neelum river catchment using Snowmelt Runoff Model

The Neelum river catchment contributes about 40% to the inflow of Mangla dam, one of the major water reservoirs in Pakistan. Most of the runoff is generated from snowmelt making the catchment susceptible to climate change. Snowmelt-Runoff Model (SRM), a simple degree-day model, has been applied in this study to forecast stream flows in the Neelum river catchment under three future climate change scenarios i.e. a) +2°C temperature increase, b) +2°C temperature increase and 20% increase in precipitation, and c) a 20% increase in precipitation. The study area was divided into 10 elevation zones with 500 m elevation interval. MODIS daily snow product MOD10A1 was used to map snow cover. MOD10A1 tiles and spatially distributed NOAA precipitation tiles were downloaded and projected and a cloud elimination technique was applied on MOD10A1 tiles. Python script tools were developed in ArcGIS to batch process NOAA and cloud free MODIS tiles to give mean precipitation and snow covered area zone-wise respectively in a fully automated process. SRM Model was calibrated for 2003-2005 and validated for 2006-2008 with 0.93 average coefficient of determination, R² and 1.46% average seasonal volume difference, D_v. Climate change scenario “b” resulted in 27% increase in the flow discharge. Scenarios “a” and “c” resulted in 21% and 6% increase in discharge respectively. The increase in flow discharge demands development of new water reservoirs in the catchment.