Variations of Temperature and Precipitation of Snowmelt Period and Its Effect on Runoff in the Mountainous Areas of Northwest China

 Snowmelt runoff, an important source of fresh water in many parts of the world, is mainly affected by meteorological elements in snowmelt period, such as snowmelt period temperature and length. The earlier the onset of snowmelt period arrives, the earlier the runoff comes into the river, which increases water evaporation and causes water resources waste. Snowmelt runoff increases in spring while that in summer will reduce accordingly, which results in water decrease during the peak period of irrigation and is not conducive to the growth of crops. Studying the variation of the snowmelt period has a significant influence on making out water resources management strategy.

Water resources of the Northwest China are mainly from snow and glacier melt water and precipitation in mountains. According to field investigation in recent years, many water managers didn’t know snowmelt period advanced clearly and often miss the best impoundment period in spring, which results in water resources shortage in summer. The study on snowmelt period change is of great significance for probing into water resources change under the influence of climate change and working out reasonable water resources management measures in the arid land of Northwest China.

Therefore, LI Baofu et al. analyzes climate change of snowmelt period and its spatial variations and explores the sensitivity of runoff to length, temperature and precipitation of snowmelt period by using the daily mean temperature and precipitation from 8 mountainous weather stations over the period 1960−2010 in the arid land of Northwest China.

The results show that mean onset of snowmelt period has shifted 15.33 days earlier while mean ending date has moved 9.19 days later. Onset of snowmelt period in southern Tianshan Mountains moved 20.01 days earlier while that in northern Qilian Mountains moved only 10.16 days earlier.

Mean precipitation and air temperature increased by 47.3 mm and 0.857°Cin the mountainous areas of Northwest China, respectively. The precipitation of snowmelt period increased the fastest, which is observed in southern Tianshan Mountains, up to 65 mm, and the precipitation and temperature in northern Kunlun Mountains increased the slowest, with increases of 25 mm and 0.617°C, respectively. While the temperature in northern Qilian Mountains increased the fastest, increasing by 1.05°C.

The annual runoff is also sensitive to the variations of precipitation and temperature of snowmelt period, because variation of precipitation induces annual runoff change by 7.69% while change of snowmelt period temperature results in annual runoff change by 14.15%. The result was published in Journal of Geographical Sciences in February 2013.