Application of Numerical Modelling to Optimise Design of a Coastguard Harbour

As part of the design process of the Sidab Coastguard harbour in Oman, 2-dimensional wave transformation modelling was carried out to generate inshore wave conditions (outside the harbour) using the MIKE21 Spectral Wave (SW) model of DHI (Danish Hydraulic Institute). The MIKE21 Boussinesq Wave (BW) model was then used to simulate the wave penetration so that acceptable wave conditions were achieved inside the harbour. Tide levels and currents (speeds and directions) inside and outside the harbour were simulated using the MIKE21 Hydrodynamic (HD) model. Finally, the MIKE21 model was used to simulate the flushing mechanism to ensure good water quality inside the harbour. Both the existing and proposed harbour layouts were modelled for operational and extreme conditions. The influence of cyclones on the design was also considered. An acceptable harbour layout was determined which provided good shelter from waves and with an exchange rate of water between the harbour and the sea which was high enough to prevent eutrophication and to allow removal of man-made pollutants such as accidental oil spills. The paper compares the findings of the present study with a range of internationally used guidelines on harbour flushing. Finally, the paper demonstrates the value of using numerical modelling technique in optimising the layout of a new harbour.