Examining Meandering Pattern of River, Using the Indexes of Curvature Coefficient and Central Angle (Case Study: Babolrud and Sajjadrud Rivers)

A great number of towns and villages are established along the rivers and especially on the terraces made by rivers. Under the influences of the river’s dynamic and discharge changes, these lands are constantly exposed to dangers such as the flood and instability of the river bed caused by the river meandering movements. Therefore, examining the meandering pattern of the rivers is necessary in order to prevent possible dangers. In this article, the study areas are Babolrud and Sajjadrud rivers in Mazandaran province in Iran which are situated on the coastal plains of Mazandaran. In this study, methodology was to use curvature coefficient (applied by Leopold and Wellman) and the central angle (cournice approach), as non-physical tools and topographical maps and aerial photographs were used as physical tools of the study. In the end, the results of the study showed that the average curvature coefficient within the area under study is equal to 2.46. This figure indicates that the ratio of the river’s meandering is high. It also shows that the rate of meandering river evolution is not the same regarding time and location. On the other hand, with regard to the obtained results of the index of curvature coefficient, 71.6 percent of the curves of this river fall into the category of evolved meandering pattern. The coefficients obtained from these models, necessitate the medium-term and long-term stabilization of the river bed, using management approaches and structural engineering.