A Novel Self-Adaptive Method in Generating DEM of Riparian Zone With Satellite Images and Corresponding Water Level in a Classification Way

Fine and new DEM of riparian zone is emergently required for hydrological and environmental modeling. With the effects of water fluctuation and submersion, acquiring DEM in the riparian zone is difficult. In this study, a self-adaptive ROC (Receiver Operating Characteristic) method was proposed to generate the DEM of riparian zone with the aid of water fluctuation (called as ROC DEM). The water extent acts as an altimeter to measure the altitude with corresponding water level. The elevation of each pixel was the optimal threshold to determine whether it was covered with water or not. With the fluctuation in water, the time-series labels of land or water and the corresponding water level of each pixel were recorded. Finally, the elevation of each pixel was obtained by acquiring the most optimal classification threshold with the ROC algorithm. The proposed method skillfully transformed the problem of acquiring the elevation of the riparian zone into a 2-class classification problem. The riparian zone in the Dongting Lake was considered as the study area to test the proposed method with the time-series Sentinel-1 SAR images and the corresponding water level. The proposed method is feasible to obtain the DEM and its results is more consistent with the actual topography comparing to other DEM products. The values of R2 between the ROC DEM and GLAS and field altitude reach to 0.7 and 0.9 respectively. This paper presents an alternate method for acquiring the topography in the riparian zone and tidal flat.