Risk approach to land reclamation: Feasibility of a polder terminal

New ports are mostly constructed on low lying coastal areas or shallow coastal waters. The quay wall and terminal yard are raised to a level well above mean sea level to assure flood safety. The resulting ‘conventional terminal’ requires large volumes of fill material often dredged from the sea, which is costly. The terminal yard of a ‘polder terminal’ lies below the outside water level and is surrounded by a quay wall flood defense structure. This saves large amounts of reclamation cost but introduces higher damage potential during flooding and thus an increased flood risk. A risk-based framework is made to determine the optimal quay wall and polder level, which is an optimization (cost benefit analysis) under two variables. Overtopping failure proves to be the dominant failure mechanism for flooding. The reclamation savings prove to be larger than the increased flood risk demonstrating that the polder terminal could be an attractive alternative to the conventional terminal. polder terminal not only ‘traditionally’ retains soil and water, it will also act as the flood defense for the polder terminal yard. The structure may consist of two sheet pile walls forming a cofferdam or a gravity structure such as a caisson. Preliminary studies showed that a polder terminal could be feasible in any low-lying area in the world, specifically in areas where low quality subsoils are present and reclamation cost are high (van beemen, 2010). A polder terminal requires smaller volumes of fill material, which saves reclamation cost. The flood risk is calculated by the multiplication of the probability of flooding and the damage of flooding. Due to a higher damage potential of the polder terminal yard during a flood, the polder terminal will have an increased risk of flooding. As a result of the lower reclamation height less settlement of the subsoil is expected, which is especially attractive for low quality subsoil often found in river deltas. In addition to the increased cost due to the higher risk of flooding a polder terminal requires a water drainage system to drain excess water out