2000～2013年鄱阳湖流域蒸散量时空变化

SPATIOTEMPORAL VARIATION OF TERRESTRIAL EVAPOTRANSPIRATION IN POYANG LAKE WATERSHED FROM 2001 TO 2013

蒸散是陆地表面水分循环的重要过程,是研究流域水资源、水循环等领域的重要参数。以鄱阳湖流域为研究对象,利用鄱阳湖流域5个主要子流域水文控制站监测流量资料和气象站监测降水资料,根据水量平衡原理计算各子流域年度蒸散,验证MODIS蒸散数据产品(ETMOD),并分析20002013年鄱阳湖流域蒸散时空变化状况和土地利用变化对蒸散量的影响。研究结果表明:（1）ETMOD具有较高的精度,年蒸散量的平均误差为165.9 mm,平均相对误差为9.78%;（2）20002013年鄱阳湖流域的年蒸散变化范围875.4912.2 mm;鄱阳湖流域总蒸散量呈先增加后减少的'几'字形季节变化特征;（3）从蒸散量与地形特征的关系看,鄱阳湖平原区蒸散量低,周边的山地丘陵区较高;各子流域的蒸散量表现为:赣江流域>抚河流域>信江流域>修水流域>饶河流域;（4）土地利用方式对蒸散量有显著的影响,各土地利用类型的平均蒸散量表现为:林地>农田>草地>未利用地。

Evapotranspiration(ET) is an important process of water cycle over land surfaces.ET is also a crucial parameter in the fields of water resources,water recycling and other fields.In this paper,water discharge from five main tributaries and precipitation from 80 meteorological stations in Poyang Lake watershed were used to verify the MODIS evapotranspiration data products(ET_(MOD)) during 2000-2013 according to the principle of water balance.The spatiotemporal pattern of ET in the Poyang watershed was analyzed.The results showed that(1) the sum of ET_(MOD) and water discharge is closed to precipitation for every sub-watershed in the Poyang Watershed.The average absolute error of annual ET was about 166 mm,the average relative error was about 10%.It means that ETMOD can be used reliably.(2) In addition to water bodies and building land,the annual ET changed from 875.4 mm to 912.2 mm during 2000-2013.The ascent happened in 2003,2012 and 2013,which exceeded the average ET value by 21.36 mm,16.93 mm and 14.86 mm respectively.The seasonal variation characteristics of the ET in the Poyang watershed increased during spring to summer and then deceased during autumn to winter.(3) The annual ET is lower for the alluvial plain around the Poyang Lake and higher for the mountainous region that is mainly covered by forest.ET was higher in the Ganjiang sub-watershed than the others,which was attributed to the high forest cover.(4) ET is affected by land use significantly,the average ET for every land use type was ordered as woodland> farmland > grassland> unused land.