天津市滨海新区地面沉降经济损失评估

Assessment of the Economic Losses Induced by Land Subsidence in Tianjin Binhai New Area

鉴于地面沉降演化的地质系统渐变性特征,从主要致灾因子考虑建立地面沉降数值模型。基于情景分析设计3种地下水开采方案:方案一,保持2007年抽水条件不变;方案二,以2007年实际开采量为基准逐年递减2%;方案三,南水北调水源逐步替换地下水开采,到最后完全替换地下水源;编译计算机程序预测地下水位动态变化过程中的地面沉降值。在此基础上,以分部门统计分析为原则,把地面沉降灾害经济损失分为23个小类;综合运用终值法、影子工程法、重置成本法、工程费用法、灾情比较法、间接损失与直接损失比例法和权重分解法等评估方法,计算不同情景下的地面沉降损失。2007-2020年,在最不利、适中和最理想3种情景下天津市滨海新区最大累计沉降量分别达640 mm5、20 mm和150 mm;地面沉降损失分别达122.21×108元、80.71×108元和43.32×108元。

Different from sudden disasters, land subsidence is a slow-onset geohazard and accumulated over years. In terms of the main causing factor, the numerical model of land subsidence was established. With three groundwater extraction scenarios, the computer program was compiled to predict the land subsidence in the process of dynamic changes of groundwater level. Maintaining the same condition of groundwater exploitation in 2007 （Scenario 1 ）, from 2007 to 2020, the maximum accumulative subsidence in Tianjin Binhai New Area （TBNA） will be 640mm and the average accumulative subsidence will be 268mm. With 2% decrease in groundwater exploitation year by year （Scenario 2）, the maximum accumulative subsidence will be 520mm and the average accumulative subsidence will be 177mm. With the water from South-to-North Water Transfer Project replacing groundwater exploitation completely （Scenario 3）, the maximum accumulative subsidence will be 150mm and the average accumulative subsidence will be 95mm. The economic losses caused by land subsidence were sorted into 23 classifications. From 2007 - 2020, the economic losses in TBNA were evaluated according to the evaluating methods of future value method, engineering cost method, shadow engineering method, replacement cost method, disaster comparison method, proportional method of indirect and direct comparison, and weight method, etc. As the result of the evaluation, the loss induced by land subsidence under Scenario 1, Scenario 2 and Scenario 3 will be 122.21 ×10^8 yuan RMB, 80.71 ×10^8 yuan RMB, and 43.32×10^8 yuan RMB respectively.