Run of the River projects along Chenab River and Its impact on Seasonal flows in Pakistan at Marala

Abstract

The role of river flow in maintaining ecological balance is well acknowledged and the river flow alterations in upper riparian zones have serious repercussion for lower riparian zones across the globe leading to trans-boundary water sharing issues. Under the umbrella of Indus water treaty (IWT) 1960, with the prime focus on Chenab catchment, current study examines the variability in inflows at Marala (1990-2020) under changing climate and increased development of Hydro power projects by India. This study tries to draw a linkage between climatic variables and variability in flows at Marala keeping in view the increased development of Runoff river project. The trend analysis of inflows have shown significant decrease in annual flows (i.e Sen’s Slope = -0.057, Tau = -0.131with p-value less than 0.05). As per quantitative assessment, there is almost more than 38 % decrease in flows as compared to 1990’s level. To assess the decreasing trends in flows, climatic variables were also explored and it was found that the precipitation (major contributing factor in runoff) data has not shown any significant negative trend in any season throughout the year which can explain decreasing flows at Marala. Moreover Snowmelt Contribution estimated for SRM were also explored to draw linkage between changes in flows and snow melt. For this purpose regression analysis was done. The results of regression have shown no significant correlation with any of climatic and hydrological parameter such as precipitation, temperature, Snow Cover area and Snow Melt Contribution. However, when annual flows were correlated using linear regression with storage capacity of dams existing in Chenab Basin, significant negative correlation was observed i.e. decreasing flows with increasing storage in the catchment.