Mapping of Planation Surfaces in the Southwest Region of Hubei Province, China—Using the DEM-Derived Painted Relief Model

Planation surfaces (PS) play a major role in reconstruction of the evolutionary history of landforms in local areas. Thus, objective and consistent mapping of planation surfaces from remotely sensed data (e.g., satellite imagery, digital elevation models (DEMs)) is paramount for interpreting the geomorphological evolution. Due to the lack of dated sedimentary covers and the difficulties of comprehensive field work, the number and age of planation surfaces in the Southwest Hubei (湖北) Province of China are still controversial. In order to map the PS in the study area, four data visualization techniques including ETM+ false color composite, grey-scale DEM, shaded relief model (SRM) and painted relief model (PRM) were examined. It is found that the PRM is the most optimal technique for planation surface mapping. The study area was successfully mapped by visual interpretation of a PRM derived from ASTER GDEM. The mapped PS was divided into five classes in terms of elevation according to previous studies, varying from 1 700–2 000 (PS1), 1 300–1 500 (PS2), 1 000–1 200 (PS3), 800–900 (PS4) to 500–600 (PS5) m. The results were partially compared with the published works. It is revealed that this method of mapping enjoys a higher accuracy and can reduce the time and effort required in the traditional mapping to a large extent. The results also demonstrated that the PRM is an effective tool for geomorphological feature mapping with considerable accuracy. The preliminary results can serve to facilitate locating representative samples for the planation surfaces dating, thus to determine the ages of PS in the study areas.