三峡水库调度运行初期荆江与洞庭湖区的水文效应

以1951-2008年实测水文资料为依据,运用对比方法,分析了三峡水库调度运行初期,荆江与洞庭湖区的连琐水文效应.结果表明:①莉江冲刷星占宜昌至城陵矶段的78.9%,其平均冲刷强度也远高于该河段;②三口分流比减少2.33%、分沙比减少2.78%;③三口多年平均入湖径流泥沙比依次减少7.7%及24.4%;④洞庭湖区淤积速率减缓26.7%、汛期水最较同期多年平均值偏少20.2%,使湖区连年季节性缺水,前者对延长湖泊寿命有利,后者酿成了连年性的夏秋连旱灾害、居民饮用水、生产用水和航运等水安全问题以及涉及到了珍禽鸟类数量和种类减少,东方田鼠种群数量极度膨胀等生态系统的稳定性;⑤湖口多年平均输沙泄洪能力增强了26.6%和3.7%,避免了溃垸决堤之灾.并认为,为适应新的江湖关系变化,必须进一步优化调整三峡水库调度运行方案,重新审视江湖治理的理念,维系江湖连通的纽带.

The Hydrological Effect between Jingjiang River and Dongting Lake during Initial Period of Three Gorges Project Operation

Based on the measured hydrological data from 1951 to 2008, the linkage hydrological effect between Jingjiang River and Dongting Lake was analyzed by comparative method after the operation of Three Gorges Project. Firstly, the results showed that the scour amount in Jingjiang River was 78.9% of the total scour amount from Yichang to Chenglingji, and that its average scour intensity was higher than the total scour intensity from Yichang to Chenglingji, too. Secondly, the dividing-water and dividing-sand ratios in the three bayous of the Jingjiang River were reduced by 2.33% and 2.78% separately. Thirdly, the average runoff and sediment in the three bayous flowing into the Dongting Lake were reduced by 7.7% and 24.4%, respectively. Fourthly, the speed of sediment filling-up was lowered by 26.7%, which would prolong natural life of the Dongting Lake. In flood season, the runoff amount of the Jingjiang River flowing into the Dongting Lake was 20.2% less than the multi-year average value. The decreases of runoff amount induced droughts in summer and fall, as well as shortage of drinking water and industry water, shipping safety, similarly led to the decrease of birds and the increase of the oriental field mice. Finally, the multi-year average values of sediment and flood discharge capacity in bayous were respectively increased by 26.6% and 3.7%, which protected embankment effectively.