Economic Consequences of Land Surface Subsidence

Abstract

Overdraft in the Santa Clara Valley ground-water basin caused land surface subsidence over an area of about 63,000 hectares with a maximum depression of about 3.6 meters between 1912 and 1967. Since cessation of overdraft and replenishment of ground-water levels in 1969, there has been no significant land surface subsidence. During the period of active land surface subsidence the following occurred: water well casings buckled; sanitary and storm drainage sewers lost capacity as a result of changes in slope; roads and railroads had to be raised to stay above floodwaters; and new levees had to be erected and old ones raised to protect developed areas against flooding from San Franciso Bay. These damages resulting from land surface subsidence are estimated to have amounted to over –130,000,000.