Shoreline Management Plan Policies

A Shoreline Management Plan (SMP) is a large-scale assessment of the risks associated with coastal processes and helps reduce these risks to people and the developed, historic and natural environments. Coastal processes include tidal patterns, wave height, wave direction and the movement of beach and seabed materials. The SMPs set the strategic policy direction for coastal management and identify the most sustainable approaches to managing the risks to the coast in the short term (Epoch 1 0-20 years), medium term (Epoch 2 20-50 years) and long term (Epoch 3 50-100 years). A set of preferred policies are identified which are assigned to 'policy units' for each SMP epoch. A 'policy unit' (PU) is a length of shoreline where a separate shoreline management policy appl
ies. PU's are defined by coastal areas that have similar characteristics in terms of coastal processes and assets at risk, that can be managed efficiently. Four policy options are available for SMPs:

- Hold the Line (HTL): an aspiration to build or maintain artificial defences so that the current position of the shoreline remains. This can involve maintaining or changing the standard of protection.
- Advance the Line (ATL): by building new defences on the seaward side of the original defences. This is rarely used and is limited to policy units where there is significant land reclamation is considered. There are no policy units in Wales assigned ATL.
- Managed Realignment (MR): by allowing the shoreline to move backwards or forwards naturally but managing the process to direct it in certain areas.
- No Active Intervention (NAI): where there is no planned investment in coastal defences or operations, regardless of whether or not an artificial defence has existed previously.
The coastal management approach for a certain section of coast may change from the status quo where a policy may no longer be practical or acceptable over 100 years. Therefore, a combination of policies may be proposed over the length of the SMP.
The dataset identifies which of the second-generation Shoreline Management Plans are applicable to a particular stretch of the Welsh coastline and the policies assigned to policy units related to that particular area. This dataset is a polyline, spatial data layer for the Welsh coast only.

海岸线管理计划（SMP）是对沿海过程相关风险的全面评估，旨在降低这些风险对人类及已开发、历史和自然环境的影响。沿海过程包括潮汐模式、波浪高度、波浪方向以及海滩和海底材料的变化。SMPs 为海岸管理设定了战略政策方向，并确定了短期（纪元1，0-20年）、中期（纪元2，20-50年）和长期（纪元3，50-100年）管理海岸风险的最可持续方法。针对每个SMP纪元，确定了一系列首选政策，并将这些政策分配给相应的‘政策单元’。‘政策单元’（PU）是指一段海岸线，其中适用的海岸线管理政策是独立的。PU由具有相似沿海过程和风险资产的海岸区域定义，这些区域可以有效地进行管理。SMPs提供了四种政策选项：

- 维持现有海岸线（HTL）：旨在建造或维护人工防御设施，以保持海岸线的当前位置。这可能涉及维持或改变保护标准。
- 前移海岸线（ATL）：通过在原始防御设施外侧建造新的防御设施。此方法很少使用，仅限于考虑进行大规模填海造地的政策单元。威尔士没有分配ATL的政策单元。
- 管理性调整（MR）：通过允许海岸线自然后退或前移，但管理该过程以引导其在特定区域。
- 无主动干预（NAI）：在没有计划投资海岸防御或运营的情况下，无论之前是否已存在人工防御设施。
对于某一特定海岸段的海岸管理方法可能会发生变化，从现状来看，某一政策可能在100年后已不再可行或可接受。因此，在SMP的整个长度上可能会提出一系列政策的组合。该数据集确定了哪些第二代海岸线管理计划适用于特定段落的威尔士海岸线，以及与该特定区域相关的政策单元分配的政策。此数据集是仅针对威尔士海岸的线形，空间数据层。