عنوان مقاله [English]
The Monitoring on route changes trend and geometric pattern of rivers is essential for identifying and evaluating eventual problems and risks in order to maintain and optimize utilization of natural resources and it is among the priorities of Geomorphology Studies. The purpose of this study is analysis of affecting factors in Kalghan Chai River and Assessment of river power and effects on the river morphology influenced by human actions is changing the river shape. The Kalghan Chai Basin is part of the Ghezel Ozen basins, which is the Garango River is its main drainage. This is located at the position 28° 46 to 30 46 east longitude and 34 37 to 46 37 north latitudes on the eastern slopes of the Sahand Mountains. In this research, studied region is range between Kalghan Dam to connect Garango River.
Material and methods
In study in order to achieve research goal were used techniques and different methods, materials of research are include of Satellite Image, Topographic map, Geological map, flow Hydrological data, data provided from Dem and field data. In this research were used methods of River Power Analysis, River specific power, Sinuosity Index, Central angle, Route Sinuosity in order to channel pattern and dynamic analysis. In order to study the river power and its effect on the erosivity, River discharge was calculated in different return periods. Then the river power was calculated by the following equation:
The flow power can also be expressed in units of the bed surface if the width of the river (W) is divided, Therefore, in order to express the power of the river at any point, it is necessary to calculate the special power of the river, is calculated by the following equation:
To study the shape and pattern of the river, coefficients Sinuosity Index, Central angle, Route Sinuosity were used. Then the Sinuosity Index size for each arc was calculated by the following equation:
The center angles of the arches on each of the intervals were calculated using the following equation
The sinuosity of the river route was also calculated using the following equation:
Results and discussion
The analysis of the characteristics of river meandering on the basis of Sinuosity Index showed that the Sinuosity Index of the study area was 1.31. And more than 90% of the curvature range is from 1.05 to 1.5, and the curvature is more than 1.5, 89% of the meandering of the study area. There are no curvatures of less than 1.05 and no more than 2 in any of the studied meanders. Therefore, the pattern of the river in study area is sinuosity. The sinuosity analysis of the river interval also showed that of the 20 interval studied, there is no Meandering interval, And 7 interval are straight pattern the rest of the interval has a sinuosity pattern. River Power Analysis showed which has the maximum River power of the Sections 20, 21 and 22, the lowest of river power are at Sections 11, 12, 13, 14 and 15. The lowest of specific river power in the sections of 19, 21 and 6. And the maximum river power in the section of 9.
Results indicated that forming of channel pattern and dynamic in studied area was controlled by hydrological processes cased flow and sediment discharge, lithological resistance of river bed and sides and the role of human factors for capture and occupation of the river bed to create gardens and farms as well as at some sections the main factor shaping is the Chanel of removal of sand from the river bed. The results of flood power and specific power analysis showed by reducing the width of the river crossing, river power increases, and the flood power depends on morphological characteristics of the river The results of this study can be used to identify of interval Maximum River power and interval affected by river erosion.