STUDY ON THE HISTORY OF LAND SUBSIDENCE IN LOWER LIAOHE RIVER PLAIN

The ground subsidence in Lower Liaohe River Plain, which results in the degradation of wetlands, has seriously impacted on not only the local economy, but also the ecological environment. Without a monitoring network, the scopes and sizes of the subsidence in this region are not clearly known. In order to find out the historical land subsidence in Lower Liaohe Plain so as to effectively improve the local economy and environment, the terrain map matching method is put forward. By collection of topographic maps of different periods, the elevations for the same spots are compared. The result shows that the land subsidence does exist in and around the concentrated areas of the oil fields and the groundwater exploitation, with maximum subduction up to 3 m. The topographic map matching effectively solves the problems of determination of scope and magnitude of subduction in the Lower Liaohe Plain. It is a practicable method to know the subsidence situation without the network monitoring data.