黑河流域上中游植被蒸散发时空演变趋势及其影响因子分析

Temporal-spatial variations in evapotranspiration in the Heihe River basin and their correlation with different meteorological/hydrological factors

结合遥感产品及气象站点数据,分析了黑河上中游2001—2012年蒸散发(ET)时空演变规律及分布格局,对比分析地表温度(LST)、空气温度、降雨、水汽压、相对湿度、风速6个环境因子对ET的影响.结果显示,2001—2012年时间段黑河上中游年ET有略微下降趋势(R2=0.01),12a的年平均ET为470.3mm,年ET最小值出现在2001年,2002年发生了"突增",2003—2007年呈现上下波动趋势,2008年发生了"突降",2008—2012年呈现了显著上升的趋势(R2=0.97),同时上、中游区域年平均ET呈不同的变化趋势.对整个研究区域生长季内ET呈显著影响的因子为降雨、空气温度和水汽压.同时,由于气象条件及地表供水条件的时空变化,针对不同区域及不同植被类型,影响ET变化的主要环境因子也发生变化,除空气温度和水汽压之外,农田ET对能量供给的太阳总辐射变化较为敏感,草地ET对水分供给的降雨变化较为敏感,林地ET则对表征大气湍流情况的风速变化较为敏感,而灌木ET对地表温度的变化较敏感.

Temporal-spatial ET variations in the Heihe River basin from 2001 2012 was analyzed,and impacts of meteorological and hydrological factors including surface temperature, air temperature, vapor pressure,wind speed,precipitation and relative air humidity on ET during vegetation growth seasons were analyzed.It was found that annual ET in the Heihe River basin from 2001 2012 showed insignificant decreasing trend (R2=0.01),average annual ET in the 12 years was 470 mm.Minimum annual ET appeared in 2001,and fluctuated from 2002 2007 after a sharp increase in 2002,a sharp declination happened in 2008, followed by a significant increase from 2008 2012 (R2 =0.97).Annual ET in upper and middle reaches showed different variations from 2001 2012. Precipitation, air temperature and vapor pressure were significantly correlated to ET.Due to the temporal-spatial variations in meteorological condition and surface water supply,the main factors influencing ET variation were different for different area and different vegetation types.With the exception of air temperature and vapor pressure,ET over crop-land was more sensitive to solar radiation;ET over grassland was more sensitive to precipitation;ET over forests was more sensitive to wind speed,ET over shrubland was more sensitive to land surface temperature.