额尔齐斯河源区森林对春季融雪过程的影响评估  

Assessment of the effects of forest on snow ablation in the headwaters of the Irtysh River,Xinjiang

作　　者：张伟[1,2] 沈永平 贺建桥[1] 贺斌[3] 吴雪娇 陈安安[1,2] 李红德[4] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冰冻圈科学国家重点实验室,甘肃兰州730000 [2]中国科学院大学,北京100049 [3]新疆阿勒泰水文水资源勘测局,新疆阿勒泰836500 [4]新疆阿克苏水文水资源勘测局,新疆阿克苏843000

出　　处：《冰川冻土》2014年第5期1260-1270,共11页Journal of Glaciology and Geocryology

基　　金：全球变化研究国家重大科学研究计划项目(2010CB951404);国家自然科学基金项目(41190084;41271083;41201062);冰冻圈科学国家重点实验室开放基金项目(SKLCS 2012-06)资助

摘　　要：春季积雪融水是额尔齐斯河河源区最重要的水资源.为探索森林对春季融雪过程的影响,于2014年融雪期在额尔齐斯河河源区的卡依尔特斯河流域,选择草地、林中空地和林下三种不同地貌条件,分别观测积雪消融过程.结果显示:积雪消融过程中,积雪深度和雪水当量的变化并不是同步的;积雪深度的减小是持续发生的,是新雪密实化作用的结果;而雪水当量仅在日均空气温度高于0℃时才出现快速的下降.森林具有显著调节空气温度的功能,三种类型观测点1.5 m处的日平均空气温度表现为草地>林下>林中空地,其中,消融期内草地的平均空气温度(-2.5℃)远高于林下(-5.4℃)和林中空地(-6.1℃);森林的存在显著减小了空气温度的日较差.草地、林中空地和林下积雪消融持续期分别为20 d、43 d和35 d,消融期平均积雪消融速率分别为2.1 mm·d-1、1.5 mm·d-1和1.2 mm·d-1,即:草地>林中空地>林下.另外,单棵树对积雪的消融速率有极其重要的影响:树冠外一定距离内积雪的消融速率约为树冠下积雪消融速率的2倍以上;但由于树冠超过70%的降雪截留效应,树冠正下方的积雪消融结束时间仍提前树冠外侧约10 d.积雪的消融由空气温度和辐射强度共同决定:当日平均空气温度<0℃时,辐射强度对积雪消融影响较大,消融过程可由空气温度和辐射强度共同描述;当温度>0℃时,单独的空气温度可直接反映消融速率的变化.研究还发现,该流域内积雪的消融主要发生在每天的14:00-19:00,该时段内积雪消融量约占全天消融总量的50%以上,这对流域内积雪洪水预报和水资源利用及管理具有重要的指导意义.Water resources from snow cover melting are the most important component of runoff in spring in the headwaters of the Irtysh River. To explore the influence of forest on snow melting in spring,three observation sites with different geomorphological types,including grassland,glade in forest and land covered by trees,were chosen to observe the snow melt processes during the snowmelt period of 2014 in the Kayiertesi River basin at the headwaters of the Irtysh River. The results indicate that the variation of snow water equivalent（ SWE） does not agree with the snow depth change： the decrease in snow depth is ongoing,but SWE begins to fast reduce only when the daily mean air temperature is above 0 ℃. The discrepancy between SWE and snow depth is caused by densification of new snow. The forests have significant function of adjusting the air temperature. The air temperature averaged from 10 to 24 March was-2. 5 ℃ in the grassland,higher than that in the land covered by trees（-5.4 ℃） and in the glade of the forest（-6.1 ℃）. The air temperature diurnal range is relatively smaller in the fine day and close to forest. The duration periods of snow melting in grassland,glade in forest and land covered by trees are 20 days,43 days and 35 days,respectively,with the average rates of snow melting of2. 1 mm·d^-1,1.5 mm·d^-1and 1. 2 mm·d^-1,respectively. In addition,a single tree also has extremely distinct effect on the surrounding snow cover melting process. The disappearance of snow cover below a tree-crown（ Scene 1） is prior to about 10 days than that of snow cover outside a certain range from the tree-crown（ Scene2）; the snow melting rate of Scene 2 is two times more than of Scene 1 because of shallower snow depth in Scene 1 induced by the tree interception. The snow melting rate is dependent on air temperature and radiation.When air temperature is below 0 ℃,the snow melting rate is sensitive to radiation,but the sensitivity gradually weakens with the rise of air temperature,and almost disappe

关 键 词：阿尔泰山 卡依尔特斯河流域 季节性积雪 森林 积雪消融 度日因子算法 

分 类 号：P343.6[天文地球—水文科学]