By examining a coastal zone with a long-term history of management strategies, the focus of this paper is on the evolution of a beach system on the updrift of a sequence of coastal interventions. Here, we review previous assessments of the natural morphodynamic adjustments of the Letitia Spit (New South Wales, Australia) in response to the construction of the Tweed River training walls (c. 1964) and a subsequent permanent artificial sand bypassing system (c. 2001) downdrift of our study site. In addition, the temporal and spatial scale of the changes on the sediment deposits is investigated for a period of 53 years (1967 to 2020). The results showed that while the immediate updrift sector (~1 km long) responds rapidly (from the first few months to two-three years) to the introduction of the coastal management structures, the extension of those impacts further updrift along the beach (~3 km) is gradual and takes decades. About two to three decades were necessary to reach a new equilibrium state after the accretionary period caused by the training wall obstruction of the littoral drift, whereas the erosional state derived from the commencement of the artificial bypassing continued for about one decade before the new equilibrium was reached. Overall, this paper contributes to the understanding of the evolution of an updrift beach in response to coastal protection works and highlights the importance of long-term morphological monitoring of the beach – from the dune to the depth of closure – for informing the planning of future coastal interventions and improving morphodynamic conceptual models focused on coastal structures and adjacent coastlines.

通过检查具有长期管理策略历史的沿海地区，本文的重点是海滩系统在一系列沿海干预措施的上升过程中的演变。在这里，我们回顾了之前对 Letitia Spit（澳大利亚新南威尔士州）的自然形态动力学调整的评估，以响应特威德河训练墙（约 1964 年）和随后的永久性人工绕沙系统（约 2001 年）的建设) 我们研究地点的下降。此外，还调查了53年（1967年至2020年）沉积物沉积变化的时空尺度。结果表明，虽然直接上升的部分（约 1 公里长）对沿海管理结构的引入反应迅速（从最初的几个月到两三年），这些影响沿着海滩（约 3 公里）进一步上升是渐进的，需要几十年的时间。在由沿岸漂移的训练墙阻塞引起的增生期之后，大约需要 2 到 30 年才能达到新的平衡状态，而在新的平衡之前，由人工绕道开始产生的侵蚀状态持续了大约 10 年。到达。总体而言，本文有助于理解上浮海滩响应海岸保护工程的演变，并强调了对海滩进行长期形态监测（从沙丘到关闭深度）的重要性，以便为未来的规划提供信息。沿海干预措施和改进形态动力学概念模型，重点是沿海结构和相邻的海岸线。