Remote Sensing Detection And Preliminary Analysis Of Surface/Subsurface Features In The Juyanze Paleo-lake Basin

Juyanze paleo-lake basin,which is not developed by mankind,is located in the arid and semi-arid area.It is rich in natural resources.In the Holocene and MIS5 stage,it has developed huge paleo-lake.Because of the sand erosion,the river drying and the lake disappeared.It is gradually evolved into today's desert and Gobi landscape,this evolution reflects the general laws of the changes in the arid lake.It is of great significance to study the surface/subsur face characteristics of Juyanze paleo-lake basin and to understand the environmental evolution of the area,also it can provide useful information for studying the process and mechanism of climate and environmental change in arid area.The variation law of surface/sub-surface features and physical and chemical properties of the lake is taken as the research point from the lake shore to the lake direction of paleo-lake basin.By using the optical remote sensing and radar remote sensing technology,the spectral reflectance of the area and the variation of the surface/subsurface scattering characteristics were obtained,and the corresponding soil physical and chemical parameters were analyzed.Finally,the interpretation of the surface/subsurface characteristics of the paleo-lake basin was completed,and the environmental changes in the area were speculated.The surface of the paleo-lake basin shows a unique "cardiopulmonary" surface feature in the optical image.By extracting the spectral reflectance,it is found that the reflectivity of the surface spectrum is gradually increased from the shore to the center by the surface salinity has the same change of the law.In order to facilitate the follow-up research work,a series of comparative experiments on the measured spectrum found that the measured spectral data and indoor simulation of the measured spectral data,but the reflectivity which is extract by the Landsat-8 and the measured data is basically consistent.So with the image extraction reflectivity supplement in the wild region which is difficult to get involved has a certain effectiveness.The radar image contains more details of the features and terrain and the polarizat io n scattering characteristics.In this paper,the polarization characteristics of the surface/subsur face of the paleo-lake basin are described by the calculation and analysis of the polarizat io n parameters.Based on Radasat-2 polarization data,the correlation coefficient,polarizat io n degree,scattering entropy,inverse entropy and average scattering angle are calculated by the correlation polarization decomposition algorithm in PolSARpro software.It is known that the whole scattering mechanism is complex,but it is different in different surface morphology and roughness.The scattering mechanism is mainly scattered in the area of the lake bank in the outer lake,and there is no single scattering in the center area.Surface roughness is an important indicator of the scattering characteristics of the surface,and from the scattering component analysis after polarization decomposition,and the scattering characteristics of the area are affected by the salt and moisture,the scattering characteristics of this area are affected by salt and moisture.Finally,the formation of the special texture of the surface is mainly caused by the surface roughness,salt content and water content,corresponding to the evolution of the climate and environment.With multi-band,wide coverage,high resolution optical image,for the surface landscape has a strong expression.The radar scatter plot can provides more detailed geometric and physical information about the surface/subsurface features,enhancing the image features and identification capabilities of the lake's remains.The combination of the two can be complementary to each other in the detection of surface/subsurface features in the arid area,which provides a new clue for the study of environmental change in arid area.