南水北调中线工程与天津地面沉降防治关系研究

Relationship between the Middle Route of the South-to-North Water Diversion Project and Land Subsidence Control in Tianjin City

天津市资源性缺水,多年持续地下水超采导致严重的地面沉降。截至2009年,天津市地面沉降覆盖区域约8 900km2,全市最大累积沉降量超过3m。南水北调中线工程初定于2014年实现通水,天津引水段工程设计方案中的供水、调蓄和输水工程均位于天津地面沉降区范围内。一方面,地面沉降导致引水工程中的重要调蓄水库设计高程和库容丢失,供水管线不均匀累积沉降对工程的运行具有一定影响。另一方面,南水北调中线工程可每年供给天津地区10.2亿m3水量,有效利用水量达8.16亿m3,这部分水量除保证重点地区用水需求外,可用来实施大规模的地下水水源转换工程。天津控制地面沉降历史经验和数值模拟结果表明,南水北调中线天津引水工程通水及大规模水源转换能有效防治地面沉降。

There has been great shortage of water resources in Tianjin City, and the excessive groundwater extraction in recent years resulted in serious land subsidence. Until 2009, the area of land subsidence coverage was approximately 8900 square kilometers in Tianjin City and the largest cumulative land subsidence was more than 3 meters. The Middle Route of the South-to- North Water Diversion Project in Tianjin City will be completed in 2014, and the water supply, storage, and transfer projects in Tianjin City are all located in the area of land subsidence. On one hand, land subsidence led to the loss of the design elevation and the capacity of the reservoirs in the project,and a certain influence of the uneven cumulative subsidence of the supply pipelines on the operation of the project. On the other hand,the annual efficient water use can be up to 816 million cubic meters in Tianjin City, which is a part of 1.02 billion cubic meters of the water supply from the South-to-North Water Diversion Project. The water use not only can meet the water demand for the key areas of Tianjin City, but also can be used to implement the largescale groundwater source conversion project. The historical experience and the numerical simulation results for land subsidence control in Tianjin City indicated that the Middle Route of the South-to-North Water Diversion Project in Tianjin City and the groundwater source conversion project can effectively control land subsidence.