青海省草地植被干旱评估及驱动力分析研究

为了研究青海省草地植被干旱特征及驱动因子，以青海省草地植被覆盖区域为对研究对象，采用水量平衡和作物需水量等方法构建干旱评估模型，评估青海省草地植被干旱时空分布特征和发生趋势，并探讨形成干旱的关键驱动因素，结果表明：整个生长季东部农业区、环青海湖区、祁连山区大部草地植被基本维持轻旱和无旱，严重干旱区域集中在青南牧区的低覆盖度草地，干旱空间总体分布基本表现为低覆盖度>中覆盖度>高覆盖度；草地植被在整个生长季的干旱灾害类型以轻旱为主，中旱次之，重旱和特旱发生频率较低，极端干旱强度呈增加态势；降水和蒸散在整个干旱发生过程中驱动作用最大，且均为负向影响，随着干旱等级加重，蒸散逐渐代替降水成为影响干旱的最重要驱动因子。风速整体上对干旱的影响表现为正向，气温、日照时数和水汽压对干旱影响作用较小。

Drought Evaluation and Driving Force Analysis of Grassland in Qinghai Province

This study was aimed to find out the drought characteristics and driving factors of grassland in Qinghai Province. The grassland coverage area in Qinghai Province was selected as the sampling site. The temporal and spatial distribution characteristics and occurrence trend of grassland drought in Qinghai Province were evaluated according to the water balance and crop water requirement and the key driving factors of drought were explored. The results showed that:during the whole growing season, the grassland in the eastern agricultural area, the peripheral area of the Qinghai Lake and the Qilian mountain area maintained light drought and no drought. The serious drought areas were mainly distributed in the southern Qinghai Pastoral Area and some low coverage grassland areas. The spatial distribution of drought was low coverage grassland > medium coverage grassland > high coverage grassland;the drought disaster type of grassland in the whole growing season was mainly light drought, followed by medium drought, the frequency of severe drought and special drought was low, and the intensity of extreme drought was increasing;precipitation and evapotranspiration played the largest driving role in the whole drought process, and they were all negative. With the aggravation of drought grade, evapotranspiration gradually replaced precipitation as the most important driving factor. On the whole, wind speed has a positive effect on drought, while temperature, sunshine hours, and water vapor pressure have little effect on drought.