چکیده:
River meanders are dynamic landforms in the paths of usually low-gradient river channels. These features are highly unstable under the influence of river dynamics and the low slope of deltas, evolving over relatively short time intervals and sometimes causing changes in the channel course. In this research, the channel changes of the Jegin River on the Makran coastal plain have been investigated. Existing evidence shows that the meandering movements and bed changes of this river are much more striking compared to other regions in Iran. Geomorphological and hydrodynamic characteristics of this river's path, including the low delta slope, fine-grained sediments, river flooding, and tectonic factors, are the main causes of the instability of the Jegin River channel. The main objective of this research is to investigate the variables influencing the changes of this river. The research technique involves comparing meandering developments and river course changes from the year 1350 to 1383 over a period of approximately 50 years. Topographic and geological maps, satellite imagery, and aerial photographs of the region constitute the primary data for investigating the spatial and temporal changes and meandering developments of the Jegin River. Longitudinal profiles were drawn to examine the slope and other morphometric data of the region. Additionally, the position of part of the river meanders was controlled with GPS during fieldwork, and sampling was simultaneously conducted to analyze sedimentological effects. The results show that the frequency and development of river meanders, as well as the course changes of the Jegin River, are primarily dependent on the low slope of the Jegin delta and subsequently on the fine-grained nature of the sediment texture. Meanwhile, severe changes in river discharge that occur periodically are the main factor in course changes. The presence of numerous coastal inlets at the base of the Jegin delta, which in the past formed the active mouths of the river, testifies to this situation. On the other hand, it seems that the active tectonics of the region and the continuous uplift of the delta base in the Makran coastline area may not be without influence on these changes, as almost all course changes have occurred upstream of the delta.
خلاصه ماشینی:
Investigation of factors affecting the pattern changes of the Jokin River in the Makran coastal plain Mojtaba Yamani 1 and Cyrus Fakhri 2 Abstract Meanders are dynamic landforms in the channel paths of usually low-gradient rivers.
The geomorphological and hydrodynamic characteristics of this river's course, including the low slope of the delta, the depositional nature of sediments, the torrential nature of the river, and tectonic factors, are the main causes of the instability of the Jokin River channel.
The results show that the frequency and development of meanders, as well as the course changes of the Jokin River, are primarily dependent on the low slope of the Jokin delta and subsequently the depositional nature of the sediment texture.
Given previous studies, the objective of this research is also to investigate the variables affecting meandering movements and the bed changes of the Jokin River located on the Makran coastal plain, as well as the temporal and spatial changes of its channel.
(Refer to page image) Materials and Methods The objective of this research was to investigate the temporal and spatial changes of meandering movements and also the course changes of the Jokin River on the Makran coastal plain and the delta of this river.
Considering the sinuosity of the river and the faults in the study area (Figure 3), the tectonic movements of the region also play a significant role in changing the course of the Jokin River and its meandering movements.
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