Geomorphologic and Environmental Hazards Assessment in Karaj-Chaloos Way (Karaj to Kandowan Tunnel)

IntroductionIn many engineering activities awareness from geomorphologic active processes in relation to the construction of roads, dams, buildings and bridges is an essential element that should be considered. The road weakness could be classified in many aspects such as climatic, topographical, geological and hydrological aspects. Constructing the transportation networks that pass through dynamic environments, finally leads to some changes in physical environments that if this changes pass over the thresholds, it may lead to environmental unbalance and also lead to some bad socio-economic feedbacks. The geomorphologic hazards are the main agents of threat to the engineering and construction activities. Awareness of geomorphologic processes and hazards is one of the main essential things in road construction. These hazards usually cause traffic problem, car accidents, and also financial losses and fatality. For example, the destruction of a large portion of northern Haraz road in Iran by a 5/5 magnitude (6/ 2 magnitude of external sources) earthquakes in 8th June of 2004.
Study AreaThe study area is the main road between the city of Karaj to Kandovan tunnel and adjacent regions, which is part of major Karaj - Chaloos roads and one of the important roads of Iran in the north and north west of Tehran province. The geographic location of the study area is between 51 to 51 degrees and 37 minutes east longitude and between 35 degrees 18 minutes to 36 degrees 15 minutes of north latitude.
Material and MethodsThis study is an experimental - application of conceptual models – which is based on mathematical and fieldwork conceptual models. For this purpose, we collect the data using library resources and web-based sources such as internet websites. We used 1:100,000 geologic maps and 1:50,000 topographic maps, LANDSAT and P5 images, and field surveys (devices and digital cameras). Then, using Google Earth software, Excel, Photoshop, ERDAS and GIS, we prepare data layers. By field work and measurements and photography, we gathered evidences for analysis and conclusions, and then by a deep understanding of active morphodynamic mechanisms and morphogenesis action, we prepared a map for geomorphologic hazards.
Results and DiscussionAccording to high topographic gradient (elevation gradient is relatively large, steep, slopes due to being stuck in the snow), that highly guarantees, morphogenesis and morphodynamic process therefore the erosion process occurred continually. In study area the first factor that causes hazards is differences in lithology, which play a fundamental role in the formation of rough shapes or topography. The index VF=3% indicates high tectonic activity of forces in the region. The freeze-thaw and mechanical weathering caused rocks to have fissures and cracks in the roadbed and surface. Morphologic changes in the road beside human activities, made imbalances and increased instability and degradation of the natural environment. Based on field studies, many tectonic forces in the region (folding, along with faults), and river channel erosion (washing), such as loss material movements, debris flows, landslides, snow and rock avalanches, cryoclastic and human morphogenesis are important geomorphologic active factors along the road.
ConclusionGeomorphologic processes in many engineering research related to the construction of roads, bridges, dams, and buildings is essential. Road engineers should understand and learn more and more about geomorphologic processes. So, before they make any plan and construct a way, they should understand geomrophologic factors affecting roads and make appropriate designs in relation to land use based on geomorphic indicators.