Volume VIII |

The Semiautomated Identification of the Planation Surfaces on the Basis of the Digital Terrain Model. Case Study: The Mehedinti Mountains (Southern Carpathians)

Abstract: The paper presents a method for the semiautomated classification of the planation surfaces, using the Digital Terrain Model (DTM) and the object-oriented analysis. The effort undergone for developing such a method has a number of motivations. The first one is that these landforms are very important for decoding the geomorphologic evolution of the relief units. The second motivation concerns the fact that their identification and mapping, by using classical means, represents a difficult demarche, which requires a lot of time. Finally, the already-known limits of the relief analysis using the DTM at pixel level impose the testing of an object-oriented analysis, in which the area under study is divided into objects of various dimensions, as homogenous as possible from the viewpoint of one or more properties. The method that we propose supposes the following steps: the realisation of the slope model and of the flow model, starting from the DTM; the division, by segmentation into objects that are as homogenous as possible from the viewpoint of the slope; the classification of the objects into landforms (planation surfaces) by using the fuzzy functions and taking into account more factors simultaneously (the average slope value, the minimum slope value, the flow coefficient and the altitude), and the selection and grouping of the identified surfaces into sculptural complexes. The first stages represent the automated part of the method, while the last one requires a detailed geomorphologic analysis of the area, as well as the validation of the results on the field. The method was firstly developed for the Godeanu Mountains, the map of the levelled surfaces (Niculescu, 1965) being used for the identification of the parameters included in the algorithm, as well as for testing the results obtained in the view of the improvement of the method. Due to the good results thus obtained, the same method was also used for mapping the levelled surfaces in the Mehedinţi Mountains, and, along with the field observations, there was realised the planation surfaces map for this relief unit.