Land Subsidence Disaster Survey and Its Economic Loss Assessment in Tianjin, China

Land subsidence is a kind of widespread geological disaster that occurs in China's coastal cities. The Tianjin metropolis has suffered negative influence of land subsidence since the 1950s. Land subsidence disaster scenarios were field surveyed and done with archival research using a variety of sources to document the historical record of the disaster, with the results showing land subsidence lead comprehensive detrimental effects on society, economy, and the natural environment. The economic loss was assessed and evaluated in urban infrastructure, building, conservancy engineering, environmental loss, secondary disaster, etc., with help of various methods, such as historical data statistics, expert judgment, shadow project calculation, modeling techniques, etc. The outcome of economic loss is about RMB135.6 billion (US$18.03 billion) up to 2007. This result, although undoubtedly incomplete, subjective, and selective, provides a believable support for the administration's decision making toward the implementation of policy regarding land subsidence disaster reduction and mitigation.