基于MOD16的陕西省蒸散量时空分布特征

基于MOD16 遥感数据集,在ERDAS IMAGINE 2013 遥感图像处理系统的支持下,通过空间建模,计算蒸散多年年平均值和月平均值,并生成图像;结合陕西省矢量边界图、土地利用矢量图,统计不同时间尺度统计行政区域和不同土地利用类型的蒸散值.在ARCGIS 10 系统中,制作陕西省2000-2013 年年、月平均蒸散分布图.利用线性回归进行蒸散时间趋势分析,采用相关系数的统计检验方法进行显著性趋势检验.进而研究了陕西省2000-2013 年蒸散量的空间分布特征和时间变化规律,分析了不同类型下蒸散量的差异性变化特征.结果表明：（1）全省年蒸散量在波动中缓慢上升,波动范围为448.0～533.3 mm·a^-1,年平均值493.3 mm·a^-1.各月蒸散量的年际变化具有季节分异特征,秋末至仲春的月蒸散具有减少的趋势,春末至仲秋的蒸散具有增加的趋势.年内蒸散量呈单峰型分布,季节性变化特征明显,蒸散主要集中在5-9 月份,最高、最低值分别出现在8 月和11 月.（2）多年平均蒸散空间格局呈现北低南高的分布规律,高植被覆盖区蒸散量较大.蒸散变化趋势不明显的面积占77.2%,蒸散显著、极显著增加的像元主要分布在陕北地区、关中地区西部和陕南丘陵浅山区,蒸散显著和极显著减少的像元主要分布在关中城市群.（3）土地利用特点影响着陕西省蒸散量的分布状况,蒸散强度大小按类型排序依次为森林〉草地〉农田〉荒漠.研究结果对于陕西有限水资源的合理利用以及水资源短缺问题的解决、旱涝监测和预警等研究具有重要意义.

Spatio-temporal Variations of Evapotranspiration in Shaanxi Province Using MOD16 Products

Based on MOD16 dataset, annual and monthly average evapotranspiration were calculated by the tool of spatial modelmaker in ERDAS IMAGINE 2013, evapotranspiration of the administrative regions and landuse types for different time scales wasstatistically computed with the vector maps of Shaanxi Province boundary and landuse. Annual and monthly averageevapotranspiration images were drew by ARCGIS 10. The time trends of evapotranspiration were analyzed by using linear regressionand the significance was tested by correlation coefficient statistical test. Then the spatio-temporal variation characteristics ofevapotranspiration from 2000 to 2013 in Shaanxi Province and the differences for evapotranspiration under different landuse typeswere analyzed. The results show that the mean annual evapotranspiration of Shaanxi Province increased slowly in the fluctuationswith values ranging from 448.0 mm·a^-1 to 533.3 mm·a^-1, and with a mean value of 493.3 mm·a^-1. The annual variation of the meanmonthly evapotranspiration presented seasonal difference, the mean evapotranspiration in the period from December to April of nextyear showed decreasing trends, the mean evapotranspiration in the period from May to October showed increasing trends. Themonthly variation of evapotranspiration within the year shows a unimodal pattern, and its peak value occurs in August, its bottomvalue occurs in November, it is mainly concentrated in the period from May to September. The spatial distribution of mean annualevapotranspiration from 2000 to 2013 was generally high over the south of the Shaanxi Province, but low in the north, especially inthe high vegetation coverage areas. The areas with insignificant variation trends were accounted for 77.2% of the total, the pixelswith significantly increased evapotranspiration were mainly distributed in north Shaanxi, Mid-Shaanxi, and hilly-mountainous areasin south Shaanxi, the pixels with significantly decreased evapotranspiration were mainly distributed in Mid-Shaanxi urbanagglomeration. The spatial d