The Review of Plan form and Variation in Sinuosity Index of Kaleibar Chai

The streams of rivers are extremely complex in nature. Rivers are beneficial for natural vegetation, animals, living organisms and human communities. The river provides the possibility of drinking water and irrigation of agricultural fields. Rivers are considered as active land cultivators with erosion and sedimentation. Some of the negative effects of rivers such as floods are considered as a natural disaster. Such natural disasters have been shown when the river by anthropogenic activities by changing the shape of the river and arched their plans change. Meandering parts of the rivers are vulnerable to floods. Therefore, river studies are very important in terms of hydraulic characteristics, sediment, width to depth ratio, morphology and arched plan. Kaleibar Chai basin has located on the North West of the country. This research pays attention to the arcuate plan of Kaleibar River from the city of Kaleibar to Jananloo village (one of the branches of Aras River). The study region is part of Kaleibar Chai River with 72 km of length. The channel consists of right, waving, meandering, and braided patterns. The study of horizontal plan of the river in relation to different active processes shows the mutual relationship between hydrological parameters and the materials in the river. The continual changes in sinuosity index in the channel are indicators of variations in the river behavior. For doing this research we used Google Earth and DEM 10m images. The river was divided into 4 openings in which topographic conditions were considered. The river sinuosity index was calculated for all 4 openings in GIS software under the formula: TSI= . In this equation TCI is topographic sinuosity index, CL is the length of the river channel, Al is the aerial length of the beginning and ending part of the channel. The maximum sinuosity index for different lengths of the Kaleibar Chai River was estimated at 1.05 to 1.83. The heterogeneity of bed materials causes erosion and deposition on the river bed of Kaleibar Chai. Erosion and depositional processes occur in the area during the spring and fall floods. The variety of materials and their sizes cause erosion and the collapse of the brinks and the loop in sinuosity index, which finally lead to channel changes. The study of sinuosity index and the identification of rivers patterns help ease the planning procedure