Quantitative Research on Meanders of AjiChay River between Khaje and Vanyar

Most of water structures and land uses being rivers or in rivers banks are somehow influencing morphological changes in rivers. Therefore survey of this phenomenon is considered as the most important part of studies projects and land uses. In this study part of the Aji Chay River has been studied between Khaje and Vanier with about 22 km length. The main aim of this study is indicating trend of morphological changes in the river, in 52-years period using the geometric parameters of the channel such as arc length, along the river valley and radius of the river circle tangent arc in the form of models the curvature coefficient and the central angle. For this purpose river path from satellite image IRS sensor Pan and aerial photos for years 1956-1995 and 1995-2008 in the ArcGIS environment in two intervals and two periods were digitized and calculated. Causes of changes using the topographic maps 1:50000 and geological 1:100000, hydrological data and field methods were investigated. Results show that 1) river on average in both periods and in both interval of their arch curvature is reduced. So that the central angle in the first interval of 137 to 100 degrees and the second interval of 160 to 148 degrees and curvature coefficient in the first range of 1/133 to 1/15 and the second period from 1/48 to 1/27 is reached. Also numbers of arcs in the years 2008 to year 1956 have increased making the year 2008 the first range number of arcs of 11 to 51 and the second interval of 19 to 86. No observed meander-like and horseshoe (oxbow) pattern on the river exists. Morphological changes of AjiChay River in the timeframe and location studied have been affected by natural factors such as loss of power of flow due to reduction of annual average water discharge and sediment, accumulation of sediment and erosion.