Modeling Flow Velocity and Determine the Scope of Erosion and Sedimentation at the Entrance Arvand River to the Persian Gulf Using GIS

Rivers affected by erosion and sedimentation, which are subject to various changes, including changing the direction of transverse and longitudinal movements, the shortcuts, changing river bed elevation change, change, change size and geometrical properties route pointed. Erosion and sedimentation studies provide the opportunity to identify the behavior of river morphology, the effects of different measures to reorganize its behavioral performance evaluated on quantitative and qualitative data And thereby allows detection of unstable and applying measures to protect and advance engineering measures It was already possible. Arvand River is one of the most important navigable rivers in Iran, and it’s the most traffic place for oil floating which don’t have any system for delivery waste materials and discharging these waste materials in water making oil pollution. Arvand River vast river in southwestern Iran in the Iran-Iraq border and the connections of the dejle, forat and Karun emerged. This study range to which the mouth of the Arvand River in the northern part of the Persian Gulf to the middle of Abadan, about 48 km from the river encompass. In this research for simulating the way of diffusion of oil pollution in Arvand Rood the Arc GIS and surfer software and three dimensional hydrodynamic model (COHERENS) are using, has been employed to solve the equations of continuity and Navier-Stokes in three dimension as well as equations of salinity and temperature. Also for displaying data Ferret software is using. First the model is verfing by using field information and then the result are showing as different senarios for diffusion oil pollution. Including modeling, taking into account different rates for Arvand, spill pollution at different times of the tidal cycle, leaks in different areas and with different loss amounts to is the possible crisis management. In this study, three-dimensional hydrodynamic model of coherence, is used to simulate the flow velocity the Navier-Stokes equations in three dimensions and equations are solved transfer salinity and water temperature separation method. Boundary conditions applied، including changes in temperature، salinity and flow rate، temperature and salinity changes and apply for open border river and tidal components O1, S2, M2 and K1 open sea in the model used for the border. To create files bathymetric mapping of the Armed Forces of hydrographic maps in the scale of 1:25, 000 use software and GIS georeferenced digital interpolation were then. In this study, a computational grid of 80 x 83 meters with an accuracy that range in size 96/52 * 97/48 km covers. One of the most effective tools in the interval erosion and unsustainable use of aerial photographs. The aim of this study was to determine the scope of erosion and sedimentation in Arvand River is using GIS. GIS is a computer-based technology that uses geographic information systems as a framework for managing and combining data, solve problems and understand situations in the past, present and future uses. Software of GIS to identify areas of erosion and sediment has been used in Arvand River And also output the final maps with erosion and sediment pollution is classified. To show the flow rate in different parts of the river, three cross-section upstream, mid-stream and river mouth for the average speed for different times and different places been brought, According to the average upstream speed is observed that the flow rate of water flow rate on the beach on the coast of Iran is Iraq, In the middle sections of the river, the average flow rate on the coast of Iran, Iraq coast, at some point in the middle of the river mouth of the river can be seen that the average speed is lower and on both sides of the river. Because of Arvand River is a tidal river, when the diffusion of oil pollution happen in specified place in high tide, it polluted the outside areas of river, and when it happen in reflow it quickly reached to Persian Golf and controlling it become difficult. The accessible result, represent the effect of tidal on oil pollution diffusion.
Table 1: different parts of the Arvand river coast erosion and sediment
long range (%) long range (km)
62. 57 45. 54 sediment on the beach
26. 75 19. 47 Beach erosion
10. 67 7. 77 Established beach
100 Total Most of the beaches in the study area are related to sediment The length of this range is 62 percent and more of beach fixed and erosion Due to the different horizontal sectioning to speed on the river, and the output flow velocity of the coherence we conclude Where the water flow rate is high, more erosion, and where less water flow speed, sediment more. Where the sediment is covered zone is the highest pollution