Geomorphological evolution of longitudinal river profiles in the Carpathians

The main rivers which drain the east and southeast side of the Eastern Carpathians and those that drain the Southern Carpathians have been analysed regarding the sediment transit, the change of the riverbeds and the type of channel deposits. In this paper, attention is focused on the concavity of the stream profile. On this basis, we tried to determine the evolution of some Carpathian rivers and thus estimate their long-term evolutionary tendencies. ncavity index of the east-Carpathian rivers shows a trend to increase from north to south from the Eastern Carpathians to the Carpathian Bend and the Bucegi Mountains. The explanation of this situation required a review of the evolutionary stages of the Eastern Carpathians, in order to establish the age and the evolutionary tendencies of the river network in our study area: the Rivers Suceava, Moldova and Bistriţa have followed the same courses since the Sarmathian (approximately 13.5 million years ago); the Trotuş River, between 10 million and 5.4 million years ago); the Rivers Putna, Buzău, Prahova, and Ialomiţa suffered the most important changes, so the age of their present course is about 2.5 million years. vers could be grouped according to the mathematical model which fits best: the exponential, exponential–logarithmic, and logarithmic model. Finally, we tried to correlate the age of the river with the form of its longitudinal profile. The customary theoretical models require that: the older a river is, the more its concavity should increase in the headwater area and should asymptotically approach a longitudinal equilibrium profile or “grade” as Davis calls it. However, the Carpathian rivers do not follow this general tendency. What we have demonstrated is that age had no influence on the form of the longitudinal profiles for the rivers on the exterior side of the Carpathians. This is because tectonic uplift was important, and this phenomenon is still present today with values of over 6 mm/year.