中国大型水库蓄水对近海相对海平面空间变化的影响

Impact of Water Impoundment of Large Reservoirs on Spatial Variation of Coastal Relative Sea Level in China

通过对我国大型水库蓄水的时空特征进行深入分析,统计得到近60年来大型水库蓄水累积的库容量已达到697km^3,占全国所有水库库容量的83.3%及全球库容量的6.5%;而2000年以来的大型水库数量及蓄水量的变化有明显的加速,库容量的变化率为16.7km^3/a,远高于1950年到2000年的4.9km^3/a的增长率;同时借助卫星重力（Gravity Recovery and Climate Experiment,GRACE）观测手段,对2000年以后主要分布在长江流域以南地区的水库进行水储量估算,结果显示GRACE仅能估算得到63%的水库变化量,两者之间的差异可能反映了该地区地下水的长期变化.结合大型水库的分布位置与库容量,基于海平面变化方程计算得到了中国近海相对海平面的空间变化.水库蓄水导致的渤海与东南沿海海域的相对海平面上升明显,最大上升高度约为8mm;而2000年以后的水库对海平面的影响主要集中在东南沿海,其中南海海域较为突出,上升高度约为2-3mm,在此期间蓄水造成的近海不同验潮站位置的海平面增长速度在0.02-0.11mm/a之间变化.

The spatial-temporal characteristics of water impoundment of large reservoirs in China are analyzed in this study.The results show that 697km^3 of water has been impounded in the large reservoirs since 1950,which amounts to 83.3% and 6.5% of the total reservoir storage capacity in China and the whole world,respectively.The numbers of large reservoirs and water storage capacity have been accelerating since 2000,and rate of the capacity change is 16.7km^3/a,much higher than the increase from 1950 to 2000 at 4.9km^3/a.Meanwhile,terrestrial water storage in the south of the Yangtze River basin is estimated by using satellite gravity data by the Gravity Recovery and Climate Experiment（GRACE）after 2000,showing that the estimate by GRACE is only 63% of total reservoir volume changes,and the difference between GRACE and real reservoir storage variations suggests a long-term trend of groundwater in this area.Based on location and capacity of the large reservoirs and sea level equation,the dam-induced spatial distributions of coastal relative sea level（RSL）are calculated.The results depict that the RSL caused the water impounded behind dams rise most quickly in the Bohai Sea and southeast coastal areas,and the maximum of the RSL is approximately about 8mm.Besides,impact of the water impoundment on the RSL mainly concentratesin the southeast coast,where the rise of the RSL is approximately about 2 to 3mm since 2000.And the rising rate of the RSL in the China coastal tide gauge locations is 0.02-0.11mm/a.