气温变化条件下融雪速率和土壤水分变化的同步观测试验

气候变化可以改变积雪持续的时间、雪盖储水量及积雪开始融化的时间,从而影响土壤水分时空分配。利用TFACE（temperature free-air controlled enhancement）的增温装置,在中国科学院天山积雪与雪崩研究站的融雪季节进行为期一个月的室外增温试验。试验包括3种处理：自然状态、增温Ⅰ和增温Ⅱ。结果表明：气温的升高和增温区内局部空气热对流加入的黑色粉尘物质加速了积雪的消融;在增温Ⅰ和增温Ⅱ条件下,积雪将提前19 d和25 d消融,相应的各土层土壤水分也出现不同程度的增加。与此同时,土壤水分最大值也提前13 d和22 d。土壤水分极值的提前预示着以融雪水为重要来源、以超渗产流模式为主的河流洪峰的提前,或者超渗产流模式向蓄满产流模式的转变。这将给区域内水资源的时空分布和管理分配带来影响。

Experimental Study on Simultaneous Observation of Snowmelt and Soil Moisture Content under Air Temperature Increase

Climate change plays an important role in dynamic changes of snow cover and soil moisture content.A warming weather in last decades had resulted in the shortening of snow cover season,reduction of water storage in snowpack and earlier snowmelt in spring,and these affected the spatiotemporal distribution of soil moisture content.In this study,a temperature increase experiment was performed at the Tianshan Station for Snow Cover and Avalanche Research during snowmelt season with a temperature increase system based on the principle of TFACE.The field experiment was conducted under three treatments: natural status,temperature increase treatment Ⅰ(air temperature was increased by about 2 ℃) and temperature increase treatment Ⅱ(air temperature was increased by about 4 ℃).The results indicated that snowmelt rate was significantly increased under both cases of temperature increase and more dust adhering to snow surface due to strong air convection caused by local warmer air.Snow cover disappeared 19 and 25 days earlier under the treatment Ⅰ and treatment Ⅱ than that under nature conditions,respectively.Corresponding to the change of snow cover status,soil moisture content was increased in varying degrees at different soil depth.Maximum soil moisture content occurred 13 and 22 days earlier,which revealed that stream flow peak might come earlier under climate change in the future in the watersheds where snowmelt water is an important water source.The field experiment provided an evidence to prove that global warming will bring a far-reaching effect on the spatiotemporal distribution of regional water resources.