中文摘要：

基于MOD16遥感蒸散发产品,利用降雨径流资料和全球陆面蒸散发估算数据集（MTE）进行精度评价,通过空间建模、趋势分析、标准差法分析了渭河流域2000-2013年实际蒸散发（ET）的年际和年内时空格局变化,探讨了不同土地利用类型下实际蒸散发的差异性变化特征。结果表明：（1）2000-2013年间渭河流域年ET呈缓慢增加趋势,年际波动较大,空间上呈北低南高的趋势,多年平均蒸散发为509.8 mm。（2）年内ET呈单峰型分布,季节性变化明显,主要集中在5~9月份,最高和最低值分别出现在8月和1月;（3）渭河流域ET变化趋势呈减少、基本不变、增加的区域面积分别占14.9%,24.7%和60.4%,年际波动程度整体呈现中度波动。（4）不同土地利用类型ET的分布总体上林地的年ET均值最高,草地、农田和城镇次之,裸地最低。

英文摘要：

Evapotranspiration（ET）,the sum of evaporation from soil and transpiration from vegetation,is of vital importance in the hydrologic cycle and governs the water cycle and energy transport among the biosphere,atmosphere and hydrosphere as a controlling factor. Accurately estimating evapotranspiration is related to issues of climate change,water resources management,crop yield estimation,environmental protection,etc. In recent years,with the development of water resources and ecological problems,particularly the urgent requirement of quantitative water management,quantitative research and pattern analysis of evapotranspiration has important practical significance in rid and semi-arid regions. In this paper,based on MOD16 evapotranspiration product,which were first validated with rainfall,runoff data and global land surface evapotranspiration estimates datasets（MTE）,the spatio-temporal variation characteristics of actual evapotranspiration（ET）in the Weihe River Basin during 2000-2013 and the differences for evapotranspiration under different land use types were analyzed with the methods of spatial modeling,trend analysis and standard deviation analysis. The results are as follows ：（1）The annual ET showed a slow upward trend and large fluctuations during 2000-2013,with the mean annual ET being 509.8mm. The spatial distribution of mean annual ET was generally high over the south of the Weihe River Basin,but low in the north.（2）The monthly ET showed a unimodal pattern with obvious seasonal difference. It is mainly concentrated from May to September,and its peak and bottom value occurred in August and January,respectively.（3）The areas with evapotranspiration trends of decreased,unchanged,increased accounted for 14.9%,24.7% and 60.4%,respectively. The characteristics of stability presented moderate.（4）The overall distribution of ET was related to land use types,with forest land being the highest,followed by grassland,farmland and towns,bare being the lowest. Besides,the change reasons of spati