Analyzing the lateral changes of Aras River channel in Ardabil province using morphological indicators

Subject Areas : Applications in water resources management

Fariba Esfandyari Darabad ¹ , sayyad asghari saraskanroud ² , Mehdi Ghandai Asl ³ , Raoof Mostafazadeh ⁴

1 - Professor, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
2 - Professor, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
3 - M.Sc in Geomorphology, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
4 - Associate Professor, Department of Watershed Management and Member of Water Management Research Institute, University of Mohaghegh Ardabili, Ardabil, Iran

Received: 2022-11-20 Accepted : 2022-12-09 Published : 2022-12-05

Keywords: River morphology, River dynamics, River channel change, Floodplain, Braided rivers,

Abstract :

Considering the morphological changes of rivers, the use of satellite images and information processing using geographic information system can be effective in quick and accurate evaluation of studies related to flooding. Quantitative geomorphic indices including the central Cornice angle, bending coefficient, Channel migration rate, Linear directional average and transect were calculated to assess Aras River morphometry. The indices were obtained in years 2000, 2010, and 2021 using RS and GIS. Results showed that the most important processes affecting the changes and lateral displacements of the Ares River channel is formation, development and advance of meanders across the floodplain, creating shortcuts and changing the routes of the channel. The development of shortcuts and changes of river path have caused a significant increase in the lateral changes of the river channel. Floods play the most important role in the shortcut formation and change of channel along Aras River. The results show that the Aras River has high mobility and lateral dynamics, which the river channel has moved more than 5 meters on average every year. However, all the quantitative geomorphic indicators show a decrease in changes and lateral displacements of the channel during recent years. The most important reason for the significant decrease in the values of quantitative geomorphic indices in the second time period (2010 to 2021) was in connection with the significant decrease in the occurrence of short-cuts and changes in the cut-off route. In general, it can be said that the decrease in the river discharge and the decrease in the intensity and frequency of floods have played the most important role in reducing the development of shortcuts and changing the path of the channel. The reduction of extreme floods has reduced the tendency for the braided pattern and increased the meander development.