ABSTRACT
The limit between low morphological units is quite difficult to be established due to the fact that the lithological, elevation and/or structure differences are hardly visible. Thus, the contact between piedmont and plain units is represented, in many cases, by areas where limits are hard to be drawn. In order to establish the way geographic information system (GIS) may contribute to the determination of the aforementioned limits, we used the situation of the limit between the Getic Piedmont and the Romanian plain and compared the obtained results to examples from other areas with different formation and evolution conditions. Presently, the Getic Piedmont undergoes a modelling process as valleys widen, torrential enlargements laterally advance, and slope denudation develop, which make difficult to establish a clear southern limit. The fan texture of the valleys, their age, the flowing direction, as well as the differences of altitude, lithology, and structure disposal represent the main elements when establishing limits even in the case of GIS analysis. The drawing of thematic layers rendering elements such as hydrographic system, hypsometry, DEM on a traditional cartographic support, orthophotoplans, satellite images, for a better interpretation of the geomorphologic aspects allow a more objective attempt of reconstructing the morphological limits.
ABSTRACT
Features of gully morphometry and associated relief characteristics emphasize that gully develop under a wide variety of rock conditions, rainfall regimes, geomorphic predisposition, and human influence. Consequently, many slopes within piedmont areas, in this case, the Getic Piedmont, are characterized by dense gully systems, as there occur excessive clearing, inappropriate land use, compaction of the soil caused by grazing, on the general background of a favourable climate. Both rainfall and runoff factors must be considered in assessing a water erosion problem. The erosional slope development within the Getic Piedmont was evaluated based on maps and field studies in the last 15 years, which emphasized that about 20 % of the total surface of the piedmont is affected by gully erosion. The results show that the factors leading to the strong gully erosion in this area include – the widely distributed friable rocks, the unique geomorphologic configuration, the strong and time-concentrated rainfall, the alternance of drought-humid periods that prepares the ground for the development of fissures in soils, the drought that influence the growth and recovery of vegetation, and the intense human activities. Gully erosion is one of the most visible forms of soil erosion, which affects its productivity, provides considerable material transport – torrential transports, debris flow, restricts land use, and threatens local communities.