Research About Differential Subsidence Of Dongting Lake Basin Based On DEM

Lake is one of the most important wetlands in which we depend on to live. The evolution of modern lakes is one of the hotspot of the geography nowadays. Study on differential subsidence has become one of the frontline of evolution research of lakes. Significant land subsidence in Donting Lake basin impedes the fast development of this area in some degree. Study on differential subsidence and arise of Donting Lake basin is needed for construction of Two-oriented society, consolidation of embankment surrounded region, practice of desilting project, flood control, and restitution of the ecosystem.The former studies showed that tectogenesis, sediment deposition and human affect were influencing factors for differential subsidence. Although there were many achievements for differential subsidence of Donting Lake basin, the concrete value of subsidence is needed to replace the average value reported and specific and public schematic diagram for subsidence of the whole area of Dongting Lake is needed either. This study can redeem the deficiency and have a certain academic value and practical significance.This research about differential subsidence based on DEM is summarized as follows:(1) Schematic diagram for subsidence of the whole area of Dongting Lake is obtained by aerial image transformation of the free SRTM 3 and ASTER GDEM data combination with space operation by geographic information systems (GIS).The deficiency of this method is discussed either.(2) The topographical map of Dongting Lake area in 50th and 80th 20st respectively with a scale 1:50,000 were obtained. Schematic diagram for subsidence of the whole area of Dongting Lake in different time was showed finally after extracting the high-scale information by determination the four representative areas of obvious subsidence through visual interpretation combined with homologue space operation. The pattern of change for four representative areas of obvious subsidence were obtained by statistical analysis of each subsidence velocity diagram.(3) By comparative analysis,it is confirmed that the three main inducing factors of tectogenesis, sediment deposition and human activities affect different areas of the Dongting Lake basin with different intensity, and these factors also impact the region for differential subsidence.(4) An idea to monitor the differential subsidence of Dongting Lake basin by D-inSAR is raised as the common leveling surveying and other method is time-taking and exertion.