西北干旱区山区融雪期气候变化对径流量的影响

利用8 个山区气象站1960-2010 年日平均气温、降水和7 个出山口水文站的年径流数据(1960-2008), 统计分析了山区融雪期开始时间、结束时间、天数、温度和降水的变化趋势及其空间差异性, 并定量评估了年径流量对融雪期温度和降水变化的敏感性。结果表明, 近50年来, 山区融雪期平均提前了15.33 天, 延迟了9.19 天;其中, 天山南部山区融雪期提前时间最长, 为20.01 天, 而延迟时间最短, 仅6.81 天;祁连山北部山区融雪期提前时间最短(10.16天), 而延迟时间最长(10.48 天)。这显示山区融雪期提前时间越长, 延迟时间则越短。山区融雪期平均降水量增加了47.3 mm, 平均温度升高了0.857℃;其中天山南部山区降水增量最大, 达65 mm, 昆仑山北部山区降水和温度增量均最小, 分别为25 mm和0.617℃, 而祁连山北部山区温度增量最高(1.05℃)。河流径流量对融雪期气候变化敏感, 降水变化诱发年径流量变化了7.69%, 温度变化使得年径流量改变了14.15%。

The Effect of Climate Change during Snowmelt Period on Streamflow in the Mountainous Areas of Northwest China

This paper, using daily mean temperature and precipitation from 8 mountainous weather stations over the period 1960-2010 in the arid region of Northwest China, analyzes snowmelt period tendency and its spatial variations and explores the sensitivity of runoff to length, temperature and precipitation of snowmelt period. The results show that mean onset of snowmelt period has a shift of 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 increases by 47.3 mm and 0.857℃ in the mountainous areas of Northwest China, respectively. The precipitation of snowmelt period with the largest increase was observed in southern Tianshan Mountains, reaching 65 mm, the precipitation and temperature in the northern Kunlun Mountains with the smallest increment increased by 25 mm and 0.617℃, respectively, while the temperature in northern Qilian Mountains rose the highest, an increase of 1.05℃. The annual streamflow is also sensitive to the variations of precipitation and temperature of snowmelt period, because variation of snowmelt period precipitation induce annual streamflow to change by 7.69% while change of snowmelt period temperature results in annual streamflow change by 14.15%.