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不同植被盖度变化下活动层水热过程是多年冻土区水能循环中一个重要的不确定因素.为了研究植被盖度变化对活动层水热过程的影响,在青藏高原多年冻土区,选择坡向、坡型和坡度趋于一致植被覆盖度分别为92%、65%、30%的坡面建立天然径流观测场,观测多年冻土活动层中的地温和水分状况.结果表明:活动层开始冻结和消融时间随着植被盖度的减少不断提前,且冻结持续时间缩短;随着植被盖度减小,活动层地温水分变化速率增大,植被起到抑制土壤地温水分变化速率的作用;植被盖度对夏季融化过程和秋季冻结过程活动层地温和水分的影响明显大于冬季降温和春季升温过程,对融化过程的影响较冻结过程更明显.
Under different vegetation cover changes, the water-heat process of the active layer is an important uncertainty in the hydropower cycle in permafrost regions.In order to study the influence of vegetation cover on the water-heat process of the active layer, in the permafrost regions of Qinghai- The natural runoff observational field was established on the slopes of which the slope, slope shape and slope tended to be consistent with the vegetation coverage of 92%, 65% and 30% respectively, and the ground temperature and water condition in the permafrost active layer were observed.The results showed that: The freezing and ablation time of the layer began to advance with the reduction of vegetation cover, and the duration of freezing was shortened. With the decrease of vegetation cover, the rate of change of ground temperature moisture in the active layer increased, and the vegetation played a role of restraining the change rate of soil temperature and moisture The effect of vegetation coverage on the summer thawing process and the mild soil moisture in the active layer in the autumn freezing process is obviously greater than that in winter and spring. The influence on the thawing process is more obvious than the freezing process.