Water Level Change Monitoring Of Plateau Wetland Based On Accurate Ranging Capability Of TerraSAR

The particularity and importance of wetlands have been widely concerned by all of the world,and water level is the key parameter of wetland ecological health status.Remote sensing technology has been widely used in wetland survey because of its high spatial resolution,wide coverage and low costs.However,there were few studies on water level in remote sensing.The paper based on the National Natural Science Foundation Surface Project——Remote Sensing Inversion of Key Hydrological and Vegetation Parameters in Plateau Wetland with Multitemporal Polarimetric SAR?because of the shortcomings of optical remote sensing,laser altimeter and radar altimeter in measuring wetland water level,the ability of TerraSAR-X in accurate ranging should be fully excavated,and the water level change of plateau wetland should be discussed based on accurate ranging.The conclusions were as follows:(1)The author had studied the methods of modifying atmospheric delays in SAR ranging,the atmospheric phase was analyzed quantitatively,and the model between the tropospheric delay and the water vapor parameters had been established.And the calculation procedure of atmospheric delay in the radar image was realized,which draw the concluation that atmospheric delay caused the error of about 1.6 m in Keluke lake during October.(2)The influence of the geophysical effects on observation points was calculated by the model of solid tide,atmospheric loading and polar tide.In this paper,the mathematical relationship between the geophysical effect and slant distance of SAR had be discussed,which draw the conclusion that the geophysical effects caused the decimeter of the error influence in slant distance of SAR.(3)We had accived accurate ranging with radar satellite TerraS AR-X based on the atmospheric delay model,the geophysical effects correction methods and the precise location of the corner reflector.In order to get the accuracy of ranging with TerraSAR-X,we had calculated the distance between SAR satellite and cornor reflection in the time of imaging,which got the concluation that the difference between two methods is 5.4cm?the result had proved the feasibility of accurate ranging with TerraSAR-X.(4)We had established the geometric relationship among accurate ranging with TerraSAR-X,the position of SAR satellite and corner reflector based on the study of response characteristics of corner reflector on SAR imaging.We had calculated the change of water level between two images in this paper.The water level difference measured by the water level indicator was 4.8cm less than the method used before,which proved the feasibility and precision of water level change monitoring of plateau wetland based on accurate ranging with TerraSAR-X.