Hydrological Response to Climate Change on Soan River Catchment

Abstract

Freshwater “inadequacy” and security have been determined to be chief global environmental problems of 21st century. Pakistan is considered as “water stressed” country in the world. About 65% of the region in Pakistan is covered by Indus river basin. For viable water resources, it is important to understand the repercussions of climate change and how this change effect water resources at basin scale and their utilization for green growth. Soan River catchment has been playing a vital role for developing water resources for the twin cities and Chakwal for the past many years. Satellite imagery was utilized for land cover classification and to investigate the land use changes in the Soan catchment, using an image processing software Earth Recourses Data Analysis System (ERDAS). The hydrological models were calibrated by using observed daily stream flows of 4 years (2007–2010), while validated for 3 years (2011–2013). Climate change projected precipitation data derived under the medium and high emission scenarios namely RCP 4.5 and RCP 8.5, respectively, was extracted for Soan river catchment from dataset developed by “Himalayan Adaptation Water and Resilience (HI-AWARE)” for “Indus, Ganges and Brahmaputra (IGB)” River basins. Bias correction of projected data was performed using delta technique and corrected daily precipitation data was applied as input of validated HEC-HMS model to check the hydrological response of catchment for future climate change conditions. For ease of understanding, analyses were carried out for three future time windows named as 2025s (2010-2040), 2055s (2041-2070) and 2085s (2071-2100). Results showed increase in built-up and urbanized area and water bodies throughout the catchment. Analysis of HI-AWARE Climate dataset based on 8 GCMs statistically downscaled at 10 km x 10 km resolution spatial grid showed overall increase in precipitation at all the 11 stations under both scenarios RCP45 and RCP 85. Both scenarios RCP45 and RCP 85 indicate the potential increase in stream flows at Dhok Pathan that could considerably lead to raise the water resources of the catchment under the changing climate during the century. So, large and small storage reservoirs are essentially required to manage and cater the flood conditions in Soan River catchment.