基于SEBS模型和Landsat 8数据的黑河下游蒸散发时空特性分析

Analysis of spatial-temporal characteristics of evapotranspiration in the lower reaches of Heihe River based on surface energy balance system model and Landsat 8 data

对黑河下游地区蒸散发量的估算及其时空特性的研究,有助于进一步了解流域水循环,合理利用水资源,防止生态环境进一步恶化。利用SEBS模型估算了黑河下游额济纳绿洲2014年15天的日蒸散量,将SEBS估算的日蒸散与不同下垫面5个站点的EC实测值进行对比,其均方根误差和确定性系数分别为1.2 mm、0.85(5个站点),0.5 mm、0.96(2个站点),表明SEBS模型的结果是合理的,可以适用于黑河下游额济纳绿洲地区的地表蒸散量的估算。同时分析了黑河下游蒸散发的时空变化规律,结果表明,黑河下游额济纳绿洲地区,蒸散发在时间上存在明显的季节变化规律:夏季>春季>秋季>冬季;空间上呈现明显的沿河分布的趋势。不同土地覆被类型蒸散发有相似的季节变化特征,但其季节变化幅度并不相同,规律为:水体>耕地>灌丛地>草地>裸土地>沙地。

The studies of evapotranspiration（ET） estimate and the spatial and temporal characteristics in the lower reaches of the Heihe River help to further understand the hydrological cycle,the rational use of water resources,preventing further deterioration of the ecological environment.Using surface energy balance system（SEBS） model to estimate the 15-day ET in 2014 and comparing with the EC measured in five different underlying sites in Ejina Oasis,the root mean square error and determination coefficient were 1.2 mm,0.85（in 5sites） and 0.5 mm,0.964（in 2 sites）,which showed that SEBS model was reasonable and could be applied to estimate ET of Ejina oasis regions.At the same time,analyzing the spatial and temporal variation of ET in the lower reaches of Heihe River showed that ET of Ejina oasis had obvious seasonal variation in the rank of summer 〉spring 〉autumn 〉winter,and had significant spatial differential along the river trend.The ET on different land cover types had similar seasonal variation,but the seasonal variation rates were not the same,decreasing as follows： water 〉arable land 〉shrub land 〉grassland 〉bare land .sandy land.