Reconstruction of surface deformation characteristics in alpine canyons under shadow conditions

Monitoring deformation in high undulating mountainous environments is critical for surface process research and disaster prevention studies. Although observations based on interferometric Synthetic Aperture Radar(InSAR) are an excellent tool for monitoring deformation, the shadow phenomena can limit its application. Based on a series of geomorphic parameters and limited InSAR observation data, surface deformations were reconstructed in areas with missing observations by constructing a random forest model to compensate for the shadow phenomenon at the grid-scale. The findings suggest that this method can be used to rebuild landscape variation characteristics in places where observation data is lacking. The dominant slope direction in the observation area corresponded to a more significant correlation between the reconstructed topography deformation characteristics and the observation. In addition, when building this model, consideration was given to the geomorphic parameter selection, elevation variation, hypsometric integral value, slope form, lithology, slope variation,and aspect variation;these parameters can significantly affect the surface deformation, which is closely related to their spatial autocorrelation. These findings are significant for eliminating the shadow phenomenon, which often occurs in In SAR observations taken over alpine canyon regions. The terrain and lithology of the underlying surface should be considered when reconstructing the surface deformation characteristics of the shadow region by using satellite observation data.

Geomorphologic patterns of dune networks in the Tengger Desert,China

Dune networks are widely distributed in the world＇s deserts,which include primary ridges and secondary ridges.However,they have not been sufficiently studied in a systematic manner and their origins and spatial and morphological characteristics remain unclear.To provide information on the geomorphology of dune networks,we analyze the software geomorphologic patterns of the dune networks in China＇s Tengger Desert using matrix and laboratory to process remote-sensing images.Based on analysis of image features and their layout in a topographic map,we identify two types of dune networks （square and rectangular dune networks） with different size and morphological structures in the Tengger Desert.Four important geomorphic pattern parameters,ridge length,spacing,orientation and defect density,are analyzed.The length of primary ridges of dune networks decreases from northwest of the desert to the southeast,resulting an increasing spacing and a transition from rectangular dune networks to square dune networks.Wind regime and sediment supply are responsible for the variation in pattern parameters.We use the spacing and defect density data to estimate the construction time of dune networks and found that the dune networks in the Tengger Desert formed since about 1.3 ka BP.