System Analysis and Numerical Simulation of Land Subsidence in Shanghai

Land subsidence has become a major geological hazard in Shanghai . Based on the view of system theory, The paper sets a numerical model of land subsidence, the results of model simulation are as follows: 1) the speed of land subsidence will be 8.81mm/a in Shanghai in the next 10 years if it can maintain present trends of load increase and groundwater mining; 2) Since 1998, we adjust the ratio of groundwater extraction and filling to 1:1, the accumulated quantity of land subsidence will rebound to 30mm in 2017, from 2018, it will continue to drop. However, the overall future land subsidence will keep the trend of slow growth; 3) Double the exploitation capacity in1998, the speed of land subsidence will be 41mm/a in 2020, the accumulative quantity of land subsidence will be close to 1m. According to the average high tide level (5.15m) in the Huangpu River in 2000-2008, the actual average high tide level of the Huangpu River will reach about 6m and exceed the orange warning response against flood and typhoon in Shanghai. If superimposing sea level rise and strong typhoon disasters, it will face with more serious flood risk.