Pressure Equalization Modules

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International Coastal Symposium

ICS2007

Gold Coast

Australia

Coastal protection based on Pressure Equalization Modules (PEM) P.Jakobsen† and
†SIC Skagen Innovation Center Skagen 9990 Denmark sic@shore.dk

C.Brøgger‡ ‡ SIC Skagen Innovation Center Skagen 9990 Denmark sic@shore.dk

ABSTRACT JAKOBSEN,P and BRØGGER,C., 2007. Coastal protection based on Pressure Equalization Modules (PEM) . Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), pg – pg. Gold Coast, Australia, ISBN Land-based activities and natural physical processes have resulted in significant modifications of the ICS 2007 International Coastal shorelines in many countries, with drastic effects on the coastal geomorphology as well as on the coastal infrastructures. There is an urgent need to introduce new and cost-effective measures that can reduce and Symposium. GoldCoast, Australia mitigate the impacts on the shorelines. SIC Skagen Innovation Centre has invented an environmentally friendly coastal protection system. The SIC system is based on pressure equalisation modules. A long-term and comprehensive test of the efficiency has been carried out on the west coast of Denmark. Furthermore, a three years scientific research programme was performed in 2005. The obtained result shows that the system is far more efficient than conventional methods such as groins, breakwaters and sand nourishment. Due to the well-known lee side erosion effect, groins and breakwaters create even greater erosion in adjacent coastal areas. Sand nourishment by dredging is in general terms a very expensive approach (about 130,000 USD / km / year in Denmark), but unfortunately it is an inefficient solution since usually the sand will disappear during the first spring tide. The result is significant already after the first year. The coastal erosion is stopped and a buffer of 476.000 cubic meter sand is built up in the fore shore and the dune front in the drained areas. 139.000 cubic meters is leeside accumulation. ADITIONAL INDEX WORDS: Beach dewatering, SIC, PEM.

INTRODUCTION
A field test over 11,0 km with the SIC vertical drain system was carried out in January 2005 and placed by Skodbjerge at the Danish west coast(fig 1) meters per year. As we see in fig. 2 the 450 meter long groin generates big leeside erosion south for the harbour.

Figure 1 The location for the field test is 5 km south of Hvide Sande harbour on the west coast of Jutland fig. 1. In relation to the channel into the harbour, was placed a groin 450 meters long in the beginning of the sixties fig. 2 The background for this long groin out in the sea was to stop the sand drift to the channel. The groin has only an effect in about two years. Afterwards the harbour authorities buy a dredger to pick up the sand from the channel and bypass the sand to the beach south of Hvide Sande harbour .The amount of sand is apx. 200.000 cubic

Figure 2 The yearly erosion rate in the field test area is 4 meter per year in the north and 1,5 meter per year in the south. In our evaluation we calculate with a average erosion rate in the test area at 2,0 meters per year The dune system is 15 meter’s high and the yearly erosion at 11 km is 330.000 cubic meter’s average per year

International Coastal Symposium, ICS2007

International Coastal Symposium

ICS2007

Gold Coast

Australia

Erosion budget Danish west coast

Field test area 11 km.

Figure 3 The central part of the Danish west coast 100 km is a high erosion area with a yearly erosion on 4,17 mill. cubic meter per year. The background for this big erosion is man made constructions with two harbours, Thorsminde and Hvide Sande. On the top we have apx. 100 groins 100 - 150 meter’s long, as increase the erosion on the west coast. The costal protection is normally based on beach and bar nourishment with 2,4 mill. cubic meter per year. The cost for the yearly bar and beach nourishment is apx. 10 mill €. The result...
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