Recommendations for the sustainable exploitation of tidal sandbanks

Abstract

A basic requirement for allowing marine aggregate (sand) extraction on the Belgian Continental Shelf (which takes place on sandbanks) is that it should not result in major environmental changes However a tidal sandbank (Kwinte Bank Flemish Banks) exploited intensively since the 1970 9 has shown evidence of significant morphological changes with the development of a 5 m deep depression in its middle section thus since February 2003 sand extraction has ceased in this area in order to study the environmental impacts and the regeneration potential of the seabed The present contribution synthesises the results of the multidisciplinary research which has taken place in the area and on the basis of these findings considers the need for an efficient management framework in both the planning and monitoring stages of the extraction The investigation has shown that extraction has had significant impacts on the seabed sedimentary character and ecology and the local hydro and sediment dynamic regime Under these conditions regeneration of the seabed is not likely in the short term and although modelling exercises have indicated possible recovery in the medium and long term this is likely to be inhibited by the lack of appropriate sediments in the area The results have provided the basis of the identification of a suite of cruel la which can assist in the strategic planning/design of marine aggregate concession zones the efficient management of marine aggregate extraction and the planning of effective environmental monitoring these criteria are related to considerations on resource location the nature/thickness of the targeted deposits morphodynamics and sediment dynamics biology and ecology and extraction practices The Kwinte Bank investigation has demonstrated also the need for intensive monitoring schemes in order to identify the morphological sedimentary and ecological impacts related to the dredging activities A critical part of these schemes should be the evaluation of the (hedging related effects against the background of the natural dynamics of the seabed thus baseline information is crucial as in its absence impact assessments are likely to remain inconclusive