构造沉降和泥沙淤积对洞庭湖区防洪的影响

作者利用洞庭盆地多年水准测量资料和洞庭湖近年的泥沙资料，对洞庭盆地的构造沉降速率和泥沙淤积速率进行了分析，从地貌学和水利学角度，对“洞庭湖盆”和“洞庭盆地”这两个不同的空间概念进行了区分，在此基础上，探讨了构造沉降和泥沙淤积对洞庭湖蓄洪空间和防洪大堤的影响。在目前洞庭湖盆被大堤围限的情况下，洞庭盆地的构造沉降运动使洞庭湖的蓄洪空间不断减小；洞庭盆地的构造沉降量虽然在一定程度上缓解了洞庭湖不断萎缩的趋势，但构造沉降对洞庭湖区的防洪形势却是不利的。构造沉降和泥沙淤积均对防洪大堤的质量提出了更高的要求，增大了洞庭湖区防洪的难度。

Influences of the Tectonic Subsidence and the Siltation on Flood Disaster Prevention Situation in the Region of Dongting Lake

With the long-term data of the geodetic sea level measurements undertaken in the Dongting Basin and the recent sediment data of Dongting Lake, we analyze the tectonic subsidence rate of the Dongting Basin and the sedimentary rate of Dongting Lake. From the point of view of geomorphology and hydrogeology, we distinguish the two different spatial concepts between "the basin of Dongting Lake" and "the Dongting Basin". Then, we discuss the influences of the tectonic subsidence and the siltation on the space of storing flood of Dongting Lake and the levees. Under the circumstance of the basin of Dongting Lake encircled by levees, the capacity of storing flood of Dongting Lake will decrease due to the tectonic subsidence. The tectonic subsidence capacity of the Dongting Basin restrains the shrinking tendency of Dongting Lake to a certain extent, but the tectonic subsidence is harmful to the situation of preventing flood disasters in the region of Dongting Lake. The better quality of levees is required due to the tectonic subsidence and the siltation, and the difficulties of preventing flood disasters are increasing in the region of Dongting Lake.