عوامل ناپايداري دامنه ها در مناطق كوهستاني غرب درياچه اروميه

Factors Affecting Mass Wasting in the Western Mountainous Regions of Orumieh Lake

The mountainous regions in the west of Orumieh lake are subject to variety of mass movements. Each of the falls and topples, debries avalanches, earth flows, mud flows, slumps and complex landslides play a role in this mass wasting. Falls and topples spread over most of the region, but as for the frequency, intensity and the damages, slumps are more significant. Falls occur in regions where limestone dissolves from beneath and Conglomerate with 4 meters depth and graded bedding is decayed in the lower parts. For mud f low and debries avalanche to occur, however removed vegetation cover plays apart, this removal in the debries avalanches zone is usually attributed to the previous removals. Despite the causes we cited to be responsible for the said mass wasting, in the occurrence of slumps and debries flow, the role of human factor is more prevalent in reducing the threshold of sliding. Although the kind and infiltration rate of the superficial deposits, the slopes and precipitation are the main factors accounting for the distribution of slumps and debries flows, human activities such as constructing irrigation canals, roads, buildings, cultivation of land, and installing water pipes has largely increased the sensitivity of the material.