长江流域1982～2005年陆地水储量变化及时空分布特征

Temporal and Spatial Distribution of Terrestrial Water Storage in the Yangtze River Basin during 1982-2005

利用PER（Precipitation-Evaporation-Runoff）水量平衡方法结合大尺度陆面水文模型VIC（Va-riable Infiltration Capacity）模拟了长江流域1982~2005年陆地水储量的时空变化特征。结果表明：PER方法模拟的长江流域陆地水储量变化与重力卫星的观测试验（GRACE）结果呈现良好的一致性,显示该方法的合理性。长江流域在1982~2005年的多年平均气温、降水、蒸散发和径流分别为13.3°C、1036.8 mm、459.4mm和576.7 mm,陆地水储量季节和年际变率分别为23.3 mm和37.0 mm,水储量这24年变化的量级在200mm左右。按照年代对1982~1990年、1991~2000年和2001~2005年这3个时段进行了统计分析,其多年平均气温分别为13.0、13.4和13.9°C,多年平均降水分别为1031.6、1051.2和1017.4 mm;与此相应的多年平均蒸散发分别为459.8、459.9和457.7 mm,多年平均径流深分别为569.0、590.1和563.8 mm;长江流域陆地水储量的季节变率分别为21.8、26.8和22.9 mm,而年际变率分别为37.7、29.8和17.6 mm。相对于基准时段（1982~1990年）,2001~2005年时段的增温速率远大于1991~2000年时段,但该时段降水却呈现减少趋势;然而两个时段的蒸散发变化不大,并且径流与降水变化趋势相同;流域平均来讲,与基准时段相比1991~2000年时段陆地水储量增加而在2001~2005年时段减少,这与降水的变化趋势相同。此外从空间分布来讲,1991~2000年和2001~2005年时段的水储量均在中部和西北呈现减少趋势,其余地区呈现增加趋势,特别地1991~2000年时段在东南地区的增加趋势尤其明显而2001~2005年时段流域的中部区域呈现明显的下降趋势,由此推断长江流域东南部水储量资源丰富,中部一些地区和西北部地区是储水量的脆弱区且对气候变化响应敏感。

The water balance method PER（Precipitation-Evaporation-Runoff） combined with the land surface model VIC（Variable Infiltration Capacity） is used to estimate the temporal and spatial distribution of TWS（Terrestrial Water Storage） over the Yangtze River basin during 1982-2005.The TWSC（Terrestrial Water Storage Change） derived from PER method agrees well with that from GRACE（Gravity Recovery and Climate Experiment） observation,which indicates its reasonability.During the whole time period the mean annual temperature,precipitation,evapotranspiration,and runoff are 13.3 °C,1036.8 mm,459.4 mm,and 576.7 mm,respectively;the seasonal and annual variabilities of TWS are 23.3 mm and 37.0 mm respectively;the magnitude of TWSC is about 200 mm.For the three time periods 1982-1900（control time）,1991-2000,and 2001-2005,the mean annual temperature is 13.0,13.4,and 13.9 °C,and the mean annual precipitation is 1031.6,1051.2,and 1017.4 mm,respectively;the corresponding mean annual evapotranspiration is 459.8,459.9,and 457.7 mm,and the mean annual runoff is 569.0,590.1,and 563.8 mm,respectively;the seasonal variability is 21.8,26.8,and 22.9 mm,while the annual variability is 37.7,29.8,and 17.6 mm;compared with 1982-1990,the warming rate during 2001-2005 is greater than that during 1991-2000;however,precipitation during 2001-2005 time period is reduced;while evapotranspiration changes a little during the three time periods and the runoff trend is similar to the precipitation trend.Compared with the control time period,basin-integrated TWS increased during 1991-2000 while decreased during 2001-2005.On the other hand,spatially TWS increased all over the basin apart from the middle and northwest of the region in comparison with control time period,and especially during 1991-2000 there is a distinct recharge of water in southeast while during 2001-2005 there is a great discharge in middle part of the basin,from which the authors inferred that the water resources of TWS in the southeast of the Yangtze River basin is abundant while that in middle and northwest of the whole basin is vulnerable and sensitive to climate change.