基于MOD16产品的三江平原蒸散量时空分布特征分析

Spatio-temporal Variations of Evapotranspiration in Sanjiang Plain Using MOD16 Products

借助Arc GIS 10.2和ENVI 4.5/ID软件平台,利用MOD16遥感数据集,统计分析了三江平原2000─2014年地表蒸散量的年际和年内时空变化状况,探讨了不同地表类型下蒸散量的差异性变化特征。首先将原始的MOD16产品进行投影转换、数据拼接和重采样等操作,在此基础上计算三江平原地区蒸散多年年均值和月均值,并分析了三江平原蒸散的变化趋势。利用三江平原的矢量边界和土地利用分类数据统计了不同时间尺度序列下各种土地利用类型的蒸散平均值,进而分析不同地物类型下蒸散量的年纪变化和季节变化特征。研究表明,(1)三江平原年蒸散量总体上呈缓慢上升趋势,波动范围为447~521mm·a^(-1),年平均值为497 mm·a^(-1)。(2)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1月。(3)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。2000─2014年蒸散变化趋势不明显的面积占88%,蒸散显著、极显著增加(8.74%)的像元主要分布在集贤市区域和双鸭山山区,蒸散显著、极显著减少的像元主要分布在河道以及城市群附近。(4)土地利用特点影响着三江平原蒸散量的分布状况,蒸散强度大小按类型排序依次为森林(46.6 mm)>草地(34.7 mm)>农田(38.38 mm)>荒漠(27.11 mm)。研究结果对于加强三江平原水资源管理与水分高效利用具有重要意义。

Based on MOD16 products, we analyzed the spatial and temporal characteristics of evapotranspiration (ET) in Sanjiang Plain during 2000─2014by using ArcGIS 10.2 and ENVI 4.5/IDL softwares.After format conversion, projection conversion, resampling and image mosaic process, annual and monthly average ET was estimated. The ET trends were also analyzed. We analyzed temporal and spatial variation of evapotranspiration with different time scales and land use types based on Sanjiang Plain vector data and land use data. Results showed that the mean annual ET of Sanjiang Plain increased slowly with a mean value of 497 mm·a-1, ranging from 447 mm·a-1 to 521 mm·a-1 during 2000─2014. Mean monthly ET presented a significant seasonal difference that the ET peaks occurred in August and the bottom values occurred in January. The spatial distribution of annual ET was generally high over the south of Sanjiang Plain, but low in the north, especially in the high vegetation coverage areas. The areas with insignificant variation were accounted for 88% of the total The pixels with significantly increased ET were mainly distributed in north Jixian urban district, and hilly-mountainous areas in Shuangyashan, while the pixels with significantly decreased ET were mainly distributed in the basin and urban area. The spatial distribution of ET is related to land use types with the order of ET intensity: woodland (46.6 mm) > grassland (34.7 mm) > farmland (34.7 mm) > desert (34.7 mm). This study supplied important information to the water resources management and water use efficiency in Sanjiang Plain.