Investigation and Estimation on the Rate of Aras River Displacement in its Floodplain

Introdution
Alluvial floodplains, and in particular those associated with the world's largest rivers, have a complex relief  that is produced by recurring erosional, and depositional events.The magnitude, heterogeneity, spatial distribution, and connectivity of this relief controls river floodwater routing and storage, sediment dispersal, and biogeochemical cyclingChannel Lateral movement and course changes are main causes for floodplain extend ,bank erosion and soil loss due to cut bank .Aras river that located in NW of Iran(from 45°E to 48°E), have many curvatures on course and due to this reason Aras is made high rate movement yearly .Aras is a boarder river and for this reason is  very important  that direction is determined .
Methodology
In this article for determining the rate  of  lateral  movement is  used  landsats  5,2 (Mss) landsat5™landsat 7(ETM+) and landsats(OLI) with 30 and 15  resoulation in 1985 to 2015 epoch. In this study is used Rm, R and MI for rate and degree movement and rate of river course curvature .
In order to determining of power flow against instability of mater in this article is used MI idex:
MI=S√Q/D50
And for determining of rate of displacement of channel, is used of Rm index:
Rm=(A/L)/Y
Discusses
Investigation on the curvature radial Aras channel show that average rate of radial is 509.62 m. In other site this rate is 515.71 m. The study also show that changes in Aras river course is vary .When wide is high ,channel  migration is excess .In recent time this changes is high ,but rate of migration in Iran site and other site is decrease to compare of past time .The average of channel migration  to Iran site is 27,21m in 2010 and other site rate is 28,32 m.
Results
Sum all area that located  at  other site  due to displacement are 1410255 m3  (1985-2015).Area in site of Iran is 2230869 m3 (1985-2015).That is to say ,difference is 820614 m3.This has meaning  that our land and soil  is placed  other site due to channel movement  .Yearly  average   displacement of channel  Aras  river  is 475 m  at Iran site   and  353 m at other site .So ,displacement at two site is vary .Over the past three decades, the fluvial dynamics of meander bends, including processes related to outer bank erosion, have been the focus of numerous scientific investigations. Despite this effort,a comprehensive understanding of the hydraulic processes of outer bank erosion—especially the role of flow turbulence—remains elusive.Because natural river flows are fully turbulent, the erosive stresses acting on the banks of meandering rivers should be related to turbulent stresses. Current models of outer bank erosion, however, rely on simple parameterization of the flow via excess velocity, excess shear stress at the bank toe, or excess flow depth .
Aras River is very dynamic .This river make curvature in its curse and cut bank .When river make meander in flow curse ,cut power of flow is increase .This high power is energy for bank cut  and  movement .Soil lost is other result for cut bank .This story is happened in northern border of Iran .