Adaptation of protection structures to the continuously rising sea level is a major topic at many coastal areas all over the world. In shallow marine environments like tidal flats these structures often aim at mitigation rather than prevention of inundations. These anthropogenic interventions, however, are prone to disturb sediment transport onto regularly inundated marshlands. This applies to ten island-like marsh areas called Halligen in the southeastern North Sea, off the coast of Schleswig-Holstein, Germany. The capability of these marsh surfaces to keep pace with sea level rise depends on vertical accretion rates due to the accumulation of suspended sediments that reach the Hallig surface during annually occurring inundations. According to latest findings, the current coastal protection structures such as revetments, dikes and breakwaters represent an obstacle for sediment transport, which intensifies the imbalance between sea level rise and vertical accretion rates on the Halligen.

A detailed hydrodynamic model of the largest Hallig Langeness and its surrounding tidal flats is applied to investigate adjustments to impermeable breakwater constructions for different inundation scenarios. The sediment transport from the tidal flats towards the marshland and the subsequent accumulation is modelled by Lagrangian particle tracking. The particle tracking results indicate almost doubling of accumulated particles by decreasing the breakwater heights from 2.56 ± 0.3 m to a constant height of 1.92 m in the moderate inundation scenario. In comparison, storm surges conditions show an increase of particle accumulation by a factor of 6.9. The results further delineate a potential increase of the recently measured vertical accretion rates by almost an order of magnitude, given an appropriate design and management of the protection structures.

在世界上许多沿海地区，保护结构适应不断上升的海平面是一个主要课题。在诸如潮滩之类的浅海环境中，这些结构通常旨在缓解而不是防止洪水泛滥。但是，这些人为干预措施容易干扰沉积物向定期淹没的沼泽地的运输。这适用于位于德国石勒苏益格-荷尔斯泰因州沿海的北海东南部的十个岛状沼泽区，称为哈利根。这些沼泽地表跟上海平面上升的能力取决于垂直的积聚率，这是由于在每年发生的洪水中，到达哈里格面的悬浮沉积物的积累。根据最新发现，目前的海岸保护结构，例如护岸，

使用最大的哈利格朗格内斯及其周围的滩涂的详细流体力学模型来研究针对不同淹没场景对不渗透防波堤构造的调整。拉格朗日粒子跟踪模拟了沉积物从潮滩向沼泽地的转移，以及随后的堆积。颗粒跟踪结果表明，在中等淹没情况下，通过将防波堤的高度从2.56±0.3 m降低到1.92 m的恒定高度，可以使堆积的颗粒几乎翻倍。相比之下，风暴潮条件显示的颗粒堆积增加了6.9倍。结果进一步表明，最近测得的垂直吸积率可能增加了近一个数量级，