THE HÂRTIBACIU TABLELAND. GEOMORPHOLOGICAL RISKS

The Hârtibaciu Tableland (4,000 sqkm, 80 km long an d 50 km wide) is a distinct subunit of the Transylvanian Tableland. Sarmatian and Panno nian sedimentary formations represent an alternation of impermeable marly-claey strata and p ermeable strata of sands, loosely cemented sandstones and conglomerates with a monocline struct ure, locally disturbed by folds of a general E-W or N-S orientation. The grade of fragmentation in point of energy and density of slopes, geodeclivity, climate and edaphic conditions, as wel l as human intervention reflect in the diversity of present-day geomorphic processes. A hierarchy of geomorphic risk classes – high, moderate and low, has been established based on slope dynamic s, as the outcome of a combination of main criteria (type of dominant process, volume of mater ial dislodged by erosion, landslides and human activity). Transition from one class to anoth er has rather a limited value for predicting process evolution. The normal evolution of natural processes in agreement with slope balance at a certain moment, tends to stabilise the terrain. Whenever ex treme natural phenomena cause imbalances on slope, bringing about changes of relief configuration and producing material damage or casualties, geomorphological hazards develop.