Quantitative evaluation of contributions of climate change and underlying surface change to the runoff at the upper catchment of Xin'anjiang ( Tunxi Hydrological Station)
Tunxi Hydrological Station ( THS) is located at the upper catchment of Xin'anjiang.The time-serial runoff data during 19552013 at THS were analyzed based on Mann-Kendall test,Pettitt test and elastic coefficient methods.The results show there is no significant increase /decrease trend,while the abrupt change point of runoff was found in 1968.The Annual Mean Runoff ( AMR) at THS has increased by 19% after 1968 with the fractional contribution of climate change to AMR increase by 30% and the fractional contribution of underlying surface change to AMR decrease by 11%.The increased precipitation has contributed to AMR increase by 19% while the decreased evaporation has contributed to AMR increase by 11%.Therefore climate change has been the main factor leading to AMR increase at THS after 1968 while the underlying surface change has slightly contributed to AMR decrease at this station.