Active landslides in Tutova catchment (Eastern Romania)

Abstract

Tutova catchment is situated in the eastern part of Romania, having a surface of about 685937 hectares. The study of active landslides actually took into consideration the analysis of causal factors (geology, morphometry, rainfall), in order to determine the susceptibility of slopes to these processes. Each potential factor of imbalance is divided into several classes of susceptibility, usually based on frequency of landslides. Given the specific of lithology and relative or absolute weight of sliding lands on geological deposits, these ones have been grouped into four classes of susceptibility. The altitude is a control factor of landslides, but only indirectly, through other geomorphometric variables. In relation to slopes, landslides are distributed almost entirely in the gap 5 to 25°, a half being on lands with slopes of 10-15°. Interpreting the distribution of landslides according to the depth of fragmentation, it appears that the maximum frequency is specific to sectors characterized by values of vertical fragmentation between 60-100 m. Gully erosion is an active factor in triggering landslides, with a very close relationship between the two types of processes. Rainfalls play an important role in triggering or reactivation of landslides. Morphodynamic response of the Moldavian Plateau diluvium trigger in the case of long-term rainfalls; fastest dynamics is found for a sequence of at least two years of excess rains, allowing accumulation of sufficient water in diluvium masses.