近20年三江平原地表蒸散发时空特征及驱动因素分析

分析地表蒸散发时空变化规律及驱动因素，对促进区域水资源的科学分配、做好生态系统水源保护具有重要意义。本文基于MOD16蒸散发遥感数据产品，采用趋势分析及显著性检验法，深入分析了近20年三江平原地表蒸散量的时空变化特征，根据Penman-Monteith公式选取与地表蒸散量（ET）相关的驱动因子，分析各驱动因子对地表蒸散量变化的影响，并构建岭回归统计模型，分析研究地表蒸散量变化的主要驱动因子及其相对贡献率。结果表明：近20年三江平原地表蒸散发（ET）年际起伏特征明显，整体呈上升趋势；研究区内91.53%的地区ET呈增加趋势，且ET分布的地域差异逐年缩小；年内ET呈单峰型周期性变化，季节差异性明显；研究区坡度对ET有正向影响，高程和风速对ET有负向影响；气温、日照时数、降水量及NDVI与ET均呈正相关性，其中降水量与ET相关性最为显著；构建岭回归驱动分析模型的决定系数R²为0.823，能够有效解释各驱动因素与ET的关系。模型计算结果表明：降水量和植被覆盖度对三江平原地表蒸散量影响较大，是影响地表蒸散量变化的主要驱动力。

Spatiotemporal characteristics and driving factors of surface evapotranspiration in Sanjiang Plain in recent 20 years

It is of great significance for analyzing the spatiotemporal variation law of surface evapotranspiration and its driving factors to promote the scientific allocation of regional water resources and to do a good job of ecological water source protection. Based on MOD16 ET remote sensing data, trend analysis and significance test method were adopted to analyze the spatial-temporal variation characteristics of surface evapotranspiration in Sanjiang Plain in recent 20 years. According to Penman-Monteith formula, driving factors related to surface evapotranspiration (ET) were selected to analyze the influence of driving factors on the change of surface evapotranspiration. Ridge regression statistical model was built to analyze the main driving factors of evapotranspiration change and their relative contribution rates. The results show that the interannual fluctuation characteristics of surface evapotranspiration (ET) in the Sanjiang Plain were obvious in recent 20 years, and the overall trend of ET was increasing. ET in 91.53% of the study area shows an increasing trend, and the regional differences of ET distribution decreased year by year. The annual ET shows unimodal periodical variation, and the seasonal difference is obvious. Slope in the study area has a positive effect on ET, while elevation and wind speed have a negative effect. Temperature, sunshine duration, precipitation and NDVI are positively correlated with ET, and precipitation has the most significant correlation with ET. The determination coefficient ^R2 of ridge regression driving analysis model is 0.823, which can effectively explain the relationship between various driving factors and ET. The results of model calculation show that precipitation and vegetation coverage have a great influence on the surface evapotranspiration in Sanjiang Plain and are the main driving forces for the change of surface evapotranspiration.