Geomorphic Effects of Road construction Operations in Geomorphological Sensitive Regions: Case study, Rural Road of Aralan (Northwest of Iran)

The road of Aralan village (38°23′21″ - 38°27′15″N and 45°33′08″- 45°34′24″E) is a 10.7km paved mountain road. Widening and repairing operations on this road have begun since 2007. Inattention to regional geomorphologic considerations at the time of these operations caused activity of some of geomorphologic processes in parts of the route. This paper is an effort to analyze the role of these kinds of operations on the landscape transformation and their geomorphic results and to investigate and analyze geomorphology of road route. The methodology of this paper is based on field studies and interpretation of geologic maps, topographic maps and aerial photos and study of literature review are used for complete field information. The results showed that, the road of Aralan crossed four geomorphological units with special processes: 1) alluvial fan (floods and debris flows), 2) red Miocene (gully erosion and landslide), 3) arcuate ridge (rockfalls, falls and landslide) and 4) high plateau (liquification and landslide). The presence of debris deposits and Quaternary alluvials on Miocene sediments (mainly marly) on three recent units has an inevitable role on slope stability. In spite of the importance of such debris deposits, removal of this debris cover and appearance of Miocene formations as the result of recent road widening and repairing operations have caused aggravation of geomorphic processes such as mass wasting and gully and rill erosion. This is a regrettable phenomenon that could be prevented by taking into consideration the assessment of geomorphologic activities; inattention to its next effects can capture us into a crisis similar to forest removal and inopportune activities in the domains of agricultural and animal husbandry.