In 1965,the United Nations Educational,Scientific and Cultural Organization (UNESC)adapted land subsidence as one of its major projects for research and development (UNESCO and IASH,1970).Since then,a great number of scientists,researchers and engineers have made tremendous efforts to investigate various relevant subjects on land subsidence.  In 1965, the United Nations Educational, Scientific and Cultural Organization (UNESC) adapted land subsidence as one of its major projects for research and development (UNESCO and IASH, 1970). Since then, a great number of scientists, researchers and engineers have made tremendous efforts to investigate various relevant subjects on land subsidence