Abstract
The watershed hydrological process is mostly influenced by land use and climate changes. The present study evaluates the relative contribution of land use and climate changes to runoff change in Rawal and Simly watersheds of Pakistan. The Mann Kendall and Pettit tests are used to find the trends and change points in the hydro-meteorological variables (runoff and precipitation) during 1983-2012. Two different models, including HEC-HMS and abcd hydrological models, are used to assess the impact of climate and land use changes on runoff. The results of both techniques were in good agreement. An increasing and decreasing trends in runoff were observed in Rawal and Simly watersheds, respectively. The runoff in Rawal watershed increased by 21.36 mm due to climate change and by 17.44 mm due to land use change. On the other hand, decrease in runoff across Simly watershed is 210.1 mm and 161.1 mm due to climate and land use changes, respectively. The relative contributions of climate and land use changes are around 55.1-56.9% and 44.9-43.4% in Rawal and Simly watersheds, respectively. The present study concludes that both climate and land use changes have a significant impact on the runoff of Margalla Hills, which could be considered for better water resources management.