The final phase of the Delta Project undertaken in the south-west of the Netherlands consisted of erecting a closable storm surge barrier in the mouth of the Eastern Scheldt and constructing two compartmentalization dams, away from the mouth, at the eastern end of the basin To limit the cost of this part of the project, it was decided to use sand instead of stone to effect the dam closures However, in view of the high flow velocities that can occur during the final stage of sandfill closures, the success of this operation very much depended on the use of the newly built storm surge barrier to reduce the magnitude of the tidal motion Due consideration was gven to the best way in which the storm surge barrier could be employed The main concerns involved were the technical implementation, environmental requirements and the protection of the barrier itself A system was therefore set up to measure and predict such effects in order to ensure that the best possible timing, and closure settings were selected for the gates in the storm surge barrier This chapter describes the system that was developed and discusses the results obtained.
After large parts of the south-west Netherlands had been flooded during the catastrophic storm surge flood of February 1953, it was decided that action must be taken to improve the safety in the area This resulted in the Delta plan being formulated Basically, the plan envisaged the construction of a large number of enclosing dams at the sea inlets in the region, to minimize the risks of future flooding The enclosure of the Eastern Scheldt was to be the final and largest single civil engineering operation in the whole project
A summary of the salient features of the Delta Project and the dates at which the major engineering works were completed is given in Figure 1
Originally, the enclosing dam for the Eastern Scheldt was to have been based on a fixed type of structure similar to that of the other dams However, a growing realization of the high ecological value of the Eastern Scheldt led to this decision being reconsidered Many people thought that other technical solutions should be found to reduce the risk of flooding In 1974 the Dutch parliament decided to close off the Eastern Scheldt by means of a closable dam which would minimize the impact on the environment The design of the Eastern Scheldt storm surge barrier (SVKO) is such that, at times of high water, the barrier can be closed by lowering a series of gates.
However, during normal tidal conditions the gates are kept open This provides an effective area through which the water can flow of 17 900 m2.
Because an opening of 17 900 m2 is insufficient to maintain the same tidal range that existed before the storm surge barrier was constructed, it was necessary to reduce the capacity of the basin behind the barrier.
Fig. 1 Salient features of the Delta Project (available in full paper)