Characteristics and affecting factors of land subsidence identification based on PSInSAR measures in Shandong Peninsula Blue-Yellow Overlapping Economic Zone

The study area is located along the overlapping zone of the Shandong Peninsula Blue Economic Zone and the Yellow River Delta Highly Efficient Ecological Economic Zone, showing important location advantages. The occurrence of land subsidence disasters has posed threats to the planning and construction of the city and the tide dike height of the port. Therefore, it is utmost important to fully recognize the characteristics of land subsidence and, in particular, to identify the main factors affecting land subsidence. Previous researches have been mainly focused on partial area using GPS and leveling survey methods without covering the whole area, which cannot support the regional city planning efficiently. Based on previous researches, the authors used PSInSAR measuring to analyze the land subsidence rate and its variation in the whole region in comparison with the leveling survey results. The results show that land subsidence has been evidently covering 75 percent of the area in recent years where there have appeared several flat districts at the junctions of Shouguang-Guangrao, northern location of Shouguang-Binhai Development Zone, northwestern Shouguang downtown, and northern location of Changyi-Binhai Development Zone, and there is an increasing trend for the harm degree of land subsidence. There are 16 settlement centers whose maximum settlement rate has reached 29-168 mm/a, and the rates of 62 percent of centers exceed 40mm/a, which are distributed in the west and northwest of the study area. Fault structure, stratigraphic structure, groundwater exploitation and ground load are the influencing factors of land subsidence, among which groundwater exploitation is the main factor of regional land subsidence, and the ground load enhances the uneven settlement of local sections, while the fault structure and stratigraphic structure provide geological background conditions for the development of land subsidence.