2000-2018年祁连山蒸散发时空变化及影响因素

Spatiotemporal Variations of Evapotranspiration and Influence Factors in Qilian Mountain from 2000 to 2018

为研究不同时期祁连山ET变化特征及其主要影响因子,基于2000-2018年的祁连山MOD16 ET数据和气象数据,利用趋势分析及相关性分析等方法,对比分析了不同时期祁连山ET的时空变化特征及其主要影响因子。结果表明:(1)MOD16 ET产品精度能够满足祁连山ET时空变化分析的要求。(2)祁连山ET时间序列在2000-2008年的增加速率为3.02 mm/a,远大于2009-2018年(1.14 mm/a)。2008年以后,由于暖湿化趋势的减缓,ET增加趋势也有所减缓;空间呈东北高西南低的分布状态,2000-2008年和2009-2018年两个时期面积显著增加分别为21.47%和9.81%。2008年以后研究区中部ET显著减少。(3)不同植被类型表现为草甸ET>耕地ET>林地ET>荒漠ET,其中耕地ET增加最为显著,草甸ET下降最明显。(4)气温和风速对祁连山ET变化影响最为显著,2000-2008年祁连山西北部的暖湿化是ET增加的主要原因。2008年以后,中部地区ET的减小是气候因素和人类活动共同作用的结果。研究可为西北干旱区气候变化决策及水资源配置提供依据。

In order to explore the characteristics of ET in Qilian Mountains and their main influencing factors at different pexiods, based on the MOD16 ET data and meteorological data of Qilian Mountain from 2000 to 2018, we used trend analysis and correlation analysis to analyze the temporal and spatial variation characteristics and main influencing factors on ET of Qilian Mountain in different periods. The results show as follows.(1) The accuracy of MOD16 ET products can meet the requirements of time-space change analysis of Qilian Mountain ET.(2) The increase rate of ET of Qilian Mountain in the time series of 2000-2008 was 3.02 mm/year, which was much larger than that in the period 2009-2018(1.14 mm/a). After 2008, because the warm and humid trend became slow, the ET increase trend also presented the slowing trend. The spatial distribution was characterized as high ET in northwest and low ET in southeast, and the significant increases of ET in the two periods 2000-2008 and 2009-2018 were 21.47% and 9.81%, respectively. ET in the central part of the study area decreased significantly after 2008.(3) ET of Qilian Mountain was positively correlated with NDVI, and the area where the ET of Qilian Mountain was extremely significantly positively correlated with NDVI accounted for 21.27% of the total area. The ETs of different vegetation types decreased in the order: meadow ET>cultivated land ET>forest ET>desert ET, and the increase of cultivated land ET was the most significant, and the decline of meadow ET was the most obvious.(4) Temperature and wind speed had the most significant impact on the ET changes in Qilian Mountain. The warming and humidification of the northwestern Qilian Mountains was the main reason for the increase of ET from 2000 to 2008. The reduction of ET in the central region was the result of the interaction of climatic factors and human activities after 2008. This study can Provide a basis for climate change decision-making and water resource allocation in arid regions of the Northwest.