عنوان مقاله [English]
River as a dynamic system can change its location and morphological characteristics based on time, geomorphologic, geological, hydrological and sometimes due to human intervention. By exact examining and identifying of these factors can obtained correct behavior of river and realized its natural reactions and possible changes. Thus the goal of this paper is reviews the role of geomorphologic and geologic factors on the geometry of the river bed and showing cause of curvature in the interval of plain and mountain. In this research, the study area is Qezel Owzan River in 47º48َ to 48 º 27َ N and 37 º 12َ to 37 º25َ E. high Length of river and its pass from erodible and Marn formation has been caused increasing River sediment
load and also the formation of bed geometry is indifferent at various intervals.
In this research to extract river path satellite images of Land Sat 7/ETM+ in 2007 have been used by Indices of WI, NDVI, False color images, Convert Tsldkap and single band which finally the middle infrared band 5 and False color images (7-4-2) was realized as the beast combination for extraction of river path. To separate the mountain and plain intervals, the study path was divided into three periods. In this paper for studying effective factors on river geometry applied criteria such as the widthdepth ratio, Entrenchment, longitudinal slop, river power, Sinuosity, central angle of meanders, plan view and Bed River lithology. For Numerical determining these parameters, satellite images, and topographic maps with the scale 1:250000, cross sections taken along the rivers and their margins, extracted River longitudinal profiles from digital elevation model (DEM) have been applied. The geological maps were prepared in all three intervals with scale 1:100000 including Miyaneh, Ardebil and Hashtchin maps.
The studying River channel Lithology indicated that formation on the sides of the river in range of floodplain has very high instability. In the mountain interval due to very strong lithology, river bed is relatively stable. The indices of Sinuosity, central angle of meanders indicated that the average wavelength in the first interval is more than the second and third intervals. This is due to migration of meanderings rings and high power of placement the bed river in the alluvial and loose bedding. In the first interval Entrenchment was very low and ratio of width to depth was very high and variable. Pattern of the river was the artery. Second interval, Entrenchment is more in compared to other intervals and width/depth is less and pattern of the river is a single channel. The third range is between tow mentioned states and its pattern is meandering to artery. Comparing river hydraulic power and Cutting strength of the rock mountain of Qezel Ozan indicated that river hasn’t capability of Narrow, rocky valley.
Result of this search showed that high length of river, passing from Marl formation and erodibility caused geometry of river in plain interval influenced by lithology of bed and Lateral erosion and Power River have main role in meandering of river that bed is Multi branches due to decrease slop and power river. While in the mountainous range tectonic is important and bed geometry was affected by tectonic parameters already designed and pattern of river path will follow from this factors. River path is single cannel due to geological formation resistance.