Changes of temperature and precipitation and their impacts on runoff in the upper Taohe River in northwest China from 1956 to 2014

Abstract

Climate change has greatly affected regional hydrological processes at temporal and spatial scales, and much attention has been focused on how runoff changed under the background of global warming in recent years. In northwest China, Taohe River provides major water resource to several semi-arid regions. To quantificationally estimate water resource, the influence of precipitation and temperature on runoff needs to be further studied. In this paper, hydro-meteorological data from 1956 to 2014 were used to analyze the changes of temperature, precipitation and runoff based on Mann–Kendall test and double cumulative curve method. The main findings were that the temperature had a significant increasing trend (0.26 °C/10a), while precipitation showed an insignificant increasing trend (0.9 mm/10a). Runoff exhibited a significant decreasing trend (− 2.7 × 108 m3/10a) and break point of the runoff occurred in 1987. Thus, compared with benchmark value during the period 1956–1987, runoff after 1987 was reduced to 70.7% of the previous level on average, from 37.5 × 108 m3 in 1956–1987 to 26.5 × 108 m3 in 1988–2014, with a decreasing rate of 29.3%; and runoff changes in each month were all decreased after 1987, particularly in September by 41.29%. Double cumulative curve and correlation results revealed that precipitation was the dominant factor controlling changes in runoff and their correlation coefficient reached up to 0.73. The magnitude of precipitation dominated runoff from April to October, accounting for more than 95% of the total annual runoff. However, runoff decreased more dramatically than precipitation after 1987, which indicated that there were some non-precipitation factors, like the increase of evaporation caused by temperature rise and human activities, responsible for the decline of runoff from 1988 to 2014. Some large-scale climate factors had a good tele-connective relation with variability of runoff. Overall, this study exhibited a scientific fact of runoff decreasing in the upper Taohe River basin and aimed to provide a basic direction for reasonable allocation of water resources by the Taohe River Diversion Project sustainably.