Quantitative contribution of climate change and land use change to runoff in tarbela catchment, pakistan

Abstract

Estimating the quantitate contribution of climate and land use change is necessary for planning water resources. Tarbela catchment in Pakistan was selected for this study. The Mann Kendall and Pettit test has been used for trend analysis of hydro climatic variables. Original climate elasticity method and improved empirical model of precipitation have been used. The results of trend analysis showed that precipitation and runoff trends decreased and potential evaporation trends increased. The annual rainfall and runoff presented a change point around the years 1999 and 1994 respectively. According to change point analysis, the runoff series was divided into two parts. The period before change point has been regarded as the pre-change period and the period after change point has been regarded as the post change period. According to the original climate elasticity method, the relative contribution of climate change and land use change has been computed as 39.3% and 60.7% respectively. Similarly the improved empirical model of precipitation showed relative contributions of climate change as 41.7% and the same for land use change as 58.3%. To validate the land use change contribution we prepared land use maps. It can be concluded that land use and climate change are responsible for runoff change in Tarbela catchment, and both methods performed well and results are in agreement.