عنوان مقاله [English]
1- Introduction :
Slope instability and falls are main risks in mountainous areas . Rock falls refers to abrupt or instantaneous movements of loosend blocks or complexes of solid rocks detached from steep rock walls (Chau et al 2004, 385). Rock falls occur mainly on the steep slopes above the vertical walls of the cliff and rocky reef areas without vegetation (Nader sefat 2006, 63). Due to the risk of these movements to human communities, one has to control them. In order to control mass movements, different aspects of the movements should be studied in detail.
The Aghlaghan chay catchment area with 166 square kilometer area, bounded by lat 38, 10-38, 44N and long 47, 46-48 E. this catchment area is located in northwestern of Iran and southwesternslope of Sabalan Mountain. Aqlaqhan Chay catchment by having mountain face and the geological, lithologic and climate conditions is sustainable for the production of falling movements. These phenomena every year causing damage to lives and property in residential areas, road destruction and widespread creation and filling of reservoir sediment and riverbed sediment is Yamchi dam. Therefore, zonation of catchment area in view of sensibility to Rock fall is very necessary .