The impact of subsidence and sea level rise in the Wadden Sea: Prediction and field verification

Abstract

Gas exploration is expected to cause subsidence in the Wadden Sea. This in turn may have impacts on hydrodynamics, tidal geomorphology, benthic fauna, wading birds and salt marshes. This paper reports on two separate multidisciplinary studies: one predicting the longer-term effects of additional gas exploitation sites relative to sea level rise, and the other a longer-term verification monitoring at an existing site on the Wadden Sea island of Ameland. Both studies conclude that subsidence will cause local impacts on tidal flats, saltmarsh and dune geomorphology, on groundwater levels and inundation frequency of coastal marshes. The induced increased sediment needs, however, are small compared to those generated by sea level rise, and can be covered by present annual sediment fluxes unless sea level rise follows the most extreme IPCC scenario of a 100 cm rise in the coming century. The effects on the biota are insignificant compared to natural temporal variation.