The Bathse Spuisluis and the syphon under the Spui canal A fresh water basin will be formed at the back of the Oosterschelde on the execution of the compartment works. In order to maintain the water level and the quality of the water in the basin a drainage system will have to lead into the open Westerschelde. A canal is being dug for this purpose through Zuid-Beveland with a discharging sluice at the end. According to the definitive design this Bathse sluice, situated in the Westerscheldedijk, consists of six tunnels which are sufficient for a discharge capacity of 100 m3/s. Discharge is regulated by the number of tunnels opened. The discharge characteristics of each tunnel have been investigated in a model. With normal use the gates are raised hydraulically to a height of 5,85 m. Energy provision comes from batteries topped up with mains voltage. The discharge construction has receding walls and a zig-zag sill. The deposit bed is 100 m long, with decreasing stone weight of the top layer. The tunnels are operated automatically either on the spot or from the Kreekrak locks. Thesyphon is a waterway under the Spuikanaal. The architectural part of both works was completed in 1984. Hydraulic works and underwater life Underwater life on hard sub-stratas under water has introduced a flora and fauna previously unknown in the Netherlands and which can therefore be considered as an enrichment. Research has been carried out since 1979 in the Oosterschelde and in the Grevelingen. The vertical layering and the relation to the type of sub-stratum have proved especially interesting aspects. As far as the layering is concerned an accurate inventory is being set up in order to be able to make forecasts which can later be tested with regard to the influence of changing tides in the Oosterschelde. It is not only the physical and chemical characteristics of the sub-strata which are the object of attention but also their form and the texture of their surface. Experiments were initiated on eleven sorts of stone. Continuation of these experiments with concrete blocks appears to be the most promising. Strengthening of the Flaauwe Werk sea defence on Goeree The last part of the strengthening and raising of the primary sea defence on Goeree, between pillars 11 and 13, is being carried out in the form of a dike with an asphalt covering. However it connects up on both sides to a coastal range of dunes. A clay dike had already been built along this stretch in the eighteenth century. A further strengthening of this coastal defence is being carried out this year as a continuation of the initial restoration afterthe catastrophe in February, 1953. There has been extensive discussion on aspects of landscape with the authorities concerned and with nature preservation societies before deciding on a design. 104

Tijdschriftenbank Zeeland

Driemaandelijks bericht Deltawerken | 1985 | | pagina 58