Quantifying the impact of mountain precipitation on runoff in Hotan River, northwestern China

It is of great significance to quantitatively assess the impact of mountain precipitation on inland river runoff in data scarce regions. Based on the corrected TRMM precipitation and runoff data, a variety of statistical methods were used to identify which areas of precipitation have an important impact on runoff in the Hotan River Basin, and to evaluate the effects that precipitation changes have on runoff at low, mid, high, and extremely high altitudes of mountainous areas. The results showed that: 1) From 1998 to 2015, the annual runoff showed a fluctuating upward trend with a rate of 11.21 × 108 m3/10 a (P < 0.05). Runoff in every season also had an increasing trend, with summer runoff the most significant at a rate of 6.09 × 108 m3/10 a. 2) The annual runoff and precipitation changes had certain synchronization, with a correlation coefficient of 0.45 (P < 0.05). Among them, the correlations between precipitation and runoff changes were highest at low and mid- altitudes, with coefficients of 0.62 and 0.55, respectively (P < 0.05). 3) 65.95% of the regional precipitation at low altitudes and 48.34% at high altitudes were significantly correlated with runoff (P < 0.05), while only 38.84% and 26.58% of regional precipitation levels at mid- and extremely high altitudes were significantly correlated with runoff. 4) The annual precipitation change in the basin was 1%, which would cause the annual runoff to change by 0.24%. In 1998–2015, the change of annual runoff caused by precipitation change at high altitudes was largest at a rate of −6.01%; the change rates of annual runoff caused by precipitation change in the low, mid-, and extremely high altitudes were −3.66%, −3.62%, and −3.67%, respectively. The results have significant scientific guidance for water resource management in arid basins.