New Developments on Coastal Protection Along the Belgian Coast

Journal of Coastal Research Fort Lauderdale, Florida Fall 1995 New Developments on Coastal Protection along the Belgian Coast Roger H. Charlier and Christian P. De Meyer HAECON, Inc. 110 Deinsesteenweg B9031 Ghent-Drongen, Belgium ABSTRACT _ CHARLIER, R.H. and DE MEYER, C.P., 1995.New developments on C08Btal protectionalong the Belgian C08Bt. Journal 0/ Coastal Research, 11(4),1287-1293. Fort Lauderdale (Florida), ISSN 0749--()208. Beach, and Partic~l.y pro.filenourishment is not a universally accepted solution for coastal protection. Its ~t has been criticized; Its temporary remedial nature emphasized. However, no better, less expensive solutl(~n has been proposed. Let nature take its course is indeed the simplest approach but one that in ~y ~8tan~.doe8 not face up to economic realities. Belgium's coastline is short and its occupation is ID~nslve. Politically and economically it cannot be left to evolve without intervention. Traditionally groins have been constructed to hold off the assault of the 80S and retain sand for the beaches. This approach has proven to be unsatisfac:oory'0even damaging. A major beach nourishment program was undertaken at the eastern ~n~; atthat time, .t was the largest such program ever carriedout and absolutely necessary t:" save the touristic nature of the area. The results have been generally praised. New problems developed In the coast's central part. The situation is far from redressed in Ostend; trouble spots appeared at th~ very western end and in~n8ive erosion has occurred in Bredene, near Ostend, a situation already described ten years ago. But rt was De Haan (a.k.a. Le Ceq-sur-mer] that immediate action became necessary and an apparently successful artificial nourishment has just been completed. This paper briefly recapitulates the work undertaken at Knokke-Heist; the proposals made for Ostend describes the present situanon In Bredene and provides a detailed account of the completed program at De Haan. ADDmONAL INDEX WORDS: Beach profile, beach nourishment, groin. shore protection, coastal engineering. INTRODUCTION are required. Nor is this remedy to erosion in Though the approach has been used with in expensive; the cost has been criticized and the creasing frequency, beach and profile nourish temporary nature underscored. Nevertheless it has ment are still not unanimously accepted as the proven successful, but hard structures require up best solution to counter coastal erosion. The soft keep and constant repair. At the Hilton Head solution which espouses nature's ways has its pro International Coastal Symposium (June 6-11, tagonists, but defenders of seawalls, groins, tri 1993), five papers dealt with artificial beach nour bars and similar structures still believe that, in ishment and no less than another five included it the long run and regardless of some negative as as a topic. The number of beach nourishment pro pects of this type of coastal engineering, they re jects, some Federal and others State or locally main preferable. sponsored, is quite impressive and their magni Cases where a mixed solution has been pro tude varies from small to very large. posed appear to be an advantage in specific sit The history of coastal protection in the United uations. Beach dewatering has been suggested as States provides a comprehensive dossier of a con an "alternative" remedy to protect retreating tinuous fight against encroachment of the sea in coasts, also gravity drainage, bypassing-back areas where only touristic values are at stake and passing, beach-scraping and beach-building. in others where an entire portuary, industrial and commercial infrastructure is threatened. Finally, OBJECTION TO NOURISHMENT some second residences on coastal islands may Undoubtedly artificial nourishment is not a have to be sacrificed. once-and-forever cure. Monitoring and upkeep A few years ago, the U.S. decided in some in stances to "let nature take its course", at least where that solution was economically tenable. In many sites such an approach is unthinkable; that 93070 received 12 July 1993; accepted in revision 29 September 1994. is the case for the Belgian coast. 1288 Charlier and DeMeyer 51'30' .-_0· ' ...... 51--J5' SCALE BELGIUM d Scale (at 5(20') Mercotorprojection - European coordinates Figure 1. Location map. Main towns and continental shelf along the North Sea coast of Belgium. THE BELGIAN COASTLINE a narrow-gauge line paralleled the coast, and ac The coast of Belgium, along the North Sea is cess to Ostend was eased by steamship connection short, about 67 km (± 42 miles) long (Figure 1), to Dover. Development had its negative effects; but its modest size is strongly balanced by its dunes were destroyed, beaches shrank. intensive occupation and major economic signif icance. A policy of letting nature take its course COASTAL PROTECTION is ruled out here. The shoreline has been sub As beaches had to be protected, sometimes not stantially modified during the historical period withstanding ill-advised strong objections of top and towns that once existed have long ago been civil servants in Brussels, who denied any "danger engulfed. to the coastline", engineers turned to the tradi Protection works were undertaken as early as tional approach of the times (XIXth and XXth the 14th century with, e.g., the construction of centuries), and a series of parallel groins, placed Count John's dyke. Except for the harbor of Ost perpendicular to the coast, were implanted. Ef end and some small fishing ports, the economic fects of coastal protection by means of groins has activity of the coastal zone was principally geared beenwidely discussed in literature. They occurred towards agriculture and husbandry in the low in Belgium as well as many other places. lying polders protected by a string of dunes. Groins could not be kept-up under German oc A new economic scene unfolded in the second cupation during the Second World War, and in half of the nineteenth century when resorts de the "fifties" and "sixties" the area of dry sand on veloped; the railroads reached the coastal towns, many beaches was either reduced at high tide to Journal of Coastal Research, Vol. II, No.4, 1995 Coastal Protection in Belgium 1289 IS I JUNE 1979 I o----211m. + HfT + ALIEIIT I(N()«.I(I· ZOUT1 HIIST ZlE'OUGG( [)UtN. STRANO -"- ZH IlJItGEH + (BRUGGEI KNOKKE HEIST .."" 191 FEBRUARY ·APRll 1981 I ,I o----2km. + H(l + ALIEOT ."OUI ZOUT( Zll.OUGG( OUIN. 5rlllAND -"'" m IEllIGiPli • IBRUGGEI KNOKKE HEIST .""" 111 I APRll·JUNE 1982 I I o___..2km. + H(l + "LIERT KNC)«KE ZOUTI ZlUOUGGl DOtH STlIANO _ ZlE IUlGEN • cBRUGGEI KNOKKE HEIST . .." 11. I SECTIONS •. 5 AND 6 MARCH MAY 1983 I I o...........2km. + H(l . ALlERT ItNOKlitE ZOUn: ZlI.OUGG( OUIN STJlANO een lIE aUtGEh • IBRUGGEI KNOKKE HEIST . +." Figure 2. Evolution of "Appelzak" gully. Journal of Coastal Research, Vol. 11, No.4, 1995 1290 Charlier and DeMeyer o SHINGLE o IIAND WEST JET1'Y 05nND tleACtl REtfADf l lTATI O'oII'AO.IECT. RETAllIE D LAYOUT Figure 3. Retained layout of the beach rehabilitation project at Oostende, Belgium. Figure 4. Relative position of feeder bar , beach and dry benched beach (De Haan, Belgium). Journal of Coastal Research, Vol. 11, No.4, 1995 Coastal Protection in Belgium 1291 Figure 5. De Haan, Belgian coast, beach prior to artificial nour ishment. a few square meters (Knokke) or was non-existent shore, and it was decided to use these in a re (Heist). The eastern sector was the most severely building program of the beaches east of the en affected by beach erosion. larged harbor. Hence , the largest artificial However erosion problems have spread, or nourishment scheme ever to be undertaken was grown, in other spots along the coast. De Moor carried out. The operation has been described and has for many years warned about a serious de discussed in the literature by the authors of this terioration of the beach at Bredene. Mode st re paper and by numerous other writers. The results mediation works have been undertaken at the of the program have been generally praised. western end of the shore in De Panne-Coxyde The Appelzak trough has gradually extended (Koksijde), and in Ostend the seawall was dam itself to within 500 m (550 yds) of the seawall aged while the beach shrank in several spots . extending from Het Zoute to the harbor of Zee brugge. The "pier" or "mole" of the port ham pered sand transport and by deflecting longshore ARTIFICIAL NOURISHMENT cur rents had a starving effect upon the beaches A unique opportunity to try a different ap situated to the east. Roovers, Kerckaert and oth proach to coastal protection was afforded by the ers have described the beach nouri shment pr oject expansion of the port of Zeebrugge. The works in detail. Coastal changes and beach evolution are included dredging of huge quantities of sand, off- being mon itored (Figure 2). T he Appe lzak trough Jou rna l of Coastal Research, Vol. 11, No.4, 1995 1292 Charlier and DeMeyer Figure 6. De Haan, Belgium, beach extension after completion of the works. or gully acted as a trap for the sediments removed were implanted but did not cure the situation. from the beaches; it has been reduced in size and The erosion remains strong and is enhanced by the westerly segment is doomed to disappear. refraction-induced wave-energy concentration and Currently a wide beach of some 100 m (330 ft) storm tides. Yet, large scale beach nourishment has been built and is being described as "stable". is excluded, because a navigation channel must New problems developed however in the oth be keptopen and beach slopes cannot be extended er-central and western-sectors of the coast. too far seaward.

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