A number of detailed study sites have been selected for each phase of the MONITOR SB&B project. Four sites were selected for the first phase, which are: 1) the area in the southeast corner of Chabahar Bay including Shaheed Beheshti (SB) and Shaheed Kalantari (SK) ports (or SBSK area), 2) Water Desalination Plant (WDP) area north of Chabahar Bay, 3) Konarak area on the southwest corner of the Bay, and 4) Iranbandar area outside of Chabahar Bay on the Pozm Headland. Selection was based on the importance of the site from economic and/or social point of view, existing problems that need to be addressed and future economic potential. Sediment transport patterns and rates were investigated in detail at the selected sites. Existing problems were investigated and possible solutions to address those problems were presented.
A combination of numerical modeling, GIS analysis of historic shoreline changes and engineering judgment and experience was employed to define sand supply and/or transport rates. The Baird in-house 2DH hydrodynamic and sediment transport model (HYDROSED) was applied to the analysis of the conditions of waves, nearshore currents and sediment transport at the selected sites. In addition, the COSMOS profile model was applied to assess variations of longshore transport rate with shoreline orientation.The hydrodynamic 2dimensional horizontal analysis and sediment transport have been implemented based on measured wave field and vertically averaged flows, in two horizontal dimensions. The considered driving forces for moving sediment are:
Orbital motion due to wave (non-linear), inshore current system which includes rotational and parallel to the coast currents and the currents back from the beach. A two dimensional transport and hydrodynamic model (Hydrosed) has been applied to analyze the waves conditions, inshore currents and sediment transport. Hydrosed model is a comprehensive two dimensional horizontal hydrodynamic and sediment transport model. This model is an internal model and is just used in the Baird Canadion company for coast areas which consists of a spectral wave transport model (in which the wave field is determined by spectral energy conservation equation, Karlsson 1969 with dissipation term due to breaking. Isobe 1987), a hydrodynamic model (Nishimura, 1988) for describing the coastal currents created by the wave and rotational currents (created by radiation stress which is estimated by spectral wave transport model), and a sediment transport model presented by Dibajnia etal. (2001). The mensioned sediment transport model considers the effect of nonlinear orbital velocities and also returning current and is based on plane flow transport equation (Dibajnia and watanabe, 1992) which has been developed by Dibajnia, 1995 for concluding suspended sediment transport on the ripples in addition to bed load.
The sensitivity aualysis of the model has been performed in the research (Dibajnia et al.2001). The model response under real and different conditions in nearshore wave media is satisfactory. For definite wave conditions, Hydrosed is able to determine an accurate location of inshore currents and sand transport, The model has been validated by experimental data and field measurements.
A key parameter in every two dimensional horizontal hydrodynamic modeling is the conditions existing in latteral and offshore boundaries. The ideal case is that both lateral bounderies are located in the areas with direct shoreline and parallel bed contours, in order to define outlet and in inlet conditions of the current and wave fields, easily. The offshore boundary is located along the depth contour at which the dopth is almost constant. Since three of the whole four detailed study sites are located in Chabahar bay, it is impossible to satisfy the boundaries like boundaries above, in a condition that a separate Hydrosed model is considered for each site. So it was decided to consider the model for the whole bay with a small mesh network.
Figure (1) Predicted offshore wave-rose in Chabahar by WW3
Figure (2) Breaking probability distribution for a wave with height of 2m and period of 10s. The waves come from south
Figure (3) Hystorical comparison of shorelines in the area SBSK
Figure (4) Hystorical comparison of shoreline changes in the fresh water maker region (WDP)
Figure (5) Hystorical comparison of shoreline changes in Jetikenarak southern
Figure (6) Hystorical comparison of shoreline, west of Iran Bandar
Figure (7) Hystorical estimations of LST potential rate in Chabahar bay