荷兰泰斯灵岛水下凹槽抛沙养滩

为了维持海岸沙丘和海滩的稳定,抵御日益加重的海岸侵蚀,荷兰泰斯灵岛于1993年5-11月对该岛中段长4.6 km(13.6~18.2 km段)的海滩实施大规模的滨面抛沙养滩工程。以驳船吹填式向两水下沙坝(最外沙坝和中沙坝)之间的凹槽区抛沙约210万m3,单宽沙量约450 m3/m。工程后监测发现已填平的凹槽区6个月后即发育出新凹槽,但是此工程后得到了8~10 a的海岸稳定,纵向运移的泥沙明显降低。事实证明,凹槽抛沙养滩通过凹槽沙的补给效应及消浪效应靠自然力缓慢向海滩滩面输沙稳定了海岸,自然扩宽了滩肩,且不破坏海陆结构,值得在日后的海滩养护工程中研究和推广。

UNDERWATER TROUGH NOURISHMENT AT TERSCHELLING ISLAND,THE NETHERLANDS

In order to maintain the stability of coastal dunes and beaches against increasing coastal erosion at the Terschelling island of The Netherlands, shoreface nourishment was implemented in the middle of the island from13.6 km to 18.2 km on November 5, 1993. 2.1 Mm3 of sands were nourished in the trough between two underwater bars, i.e. the most outside bar and the middle bar, and the average volume of nourished sand is around 450 m3/m per meter of width. Six months later, a new trough appeared again at the site of nourishment. However, the beach remained in stability for 8~10 years. The vertical movement of sediment decreased obviously. It is confirmed that trough nourishment may weaken the wave effect and transfer the sediments to the beachface to stabilize the coast and to broaden the berm automatically without damage of the sea-land pattern. It is worth to research and promote beach nourishment as such in the future.