NSW Estuarine Inundation - 2025

This dataset comprises spatial inundation layers for all estuaries in New South Wales (NSW), representing both current (2020 baseline) and projected future inundation from a range of tidal water level exceedances at decadal intervals from 2020 through to 2150, under a range of sea level rise (SLR) scenarios associated with the Intergovernmental Panel on Climate Change’s shared socio-economic pathways (i.e. SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5 medium confidence and SSP5-8.5 low confidence). The inundation mapping is underpinned by a comprehensive estuarine tide gauge database, a water surface fitting methodology that accounts for spatial variability in water levels both between and along individual estuaries, and the most recent digital elevation model (DEM) with 5 m horizontal resolution.\r\n\r\nDaily maximum water levels were analysed to derive empirical exceedance frequencies, enabling the delineation of inundation extents for a series of exceedance thresholds. The focus is on relatively frequent tidal inundation events (i.e. 1 day/year, 3.6 days/year, 36.5 days/year and 182.5 days/year) rather than flood events, which require more complex hydrological modelling. To isolate tidal influences, records affected by flooding were systematically removed prior to analysis using a threshold-based method. In estuaries lacking direct gauge data (ungauged estuaries), proxy data from hydrologically and geomorphologically similar nearby estuaries were utilised.\r\n\r\nFuture inundation conditions were estimated at decadal intervals through to 2150, incorporating probabilistic SLR projections derived from the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6), as accessed via NASA’s AR6 sea level rise projection tool. Sea level rise was added to the existing water level time series, randomly sampled from future sea level rise distributions fitted to the AR6 IPCC projection data. In estuaries with available hydrodynamic models, modifications to tidal dynamics under SLR (i.e., amplification or attenuation) were also considered through the application of estuary-specific adjustment factors. \r\n\r\nWater-level surface layers were constructed from the water-level exceedance distributions for indicative exceedance frequencies (1 day/year, 3.6 days/year, 36.5 days/year and 182.5 days/year). Inundation was mapped by overlaying the water-level surface layers onto a 5-metre resolution digital elevation model derived from the best available high-resolution LiDAR data. Each scenario is represented by two polygon layers: one depicting primary inundation (areas hydrologically connected to the estuary), and the other depicting isolated inundation (low-lying areas disconnected by more than 5 metres, yet potentially connected through stormwater infrastructure).\r\n\r\nDetailed information on file naming conventions, directory structure, shapefile attributes, and layer descriptions is provided in the accompanying ReadMe documentation. Readers are also encouraged to refer to the accompanying technical report (NSW Coastal Erosion and Inundation Hazards and Exposure Assessment – Technical Report, 2025) for detailed information on the methodology, assumptions, and modelling procedures.\r\n\r\nThe primary purpose of this dataset is to inform strategic coastal and estuarine land use planning, early-stage risk assessment, and the prioritisation of adaptation needs across NSW. Its consistency across the state facilitates comparative exposure analysis and regional prioritisation. However, while the mapping provides a scientifically robust basis for understanding tidal inundation risk, it is not a substitute for detailed, local-scale flood or inundation modelling required for statutory planning or engineering design purposes.\r\n

本数据集涵盖新南威尔士州（New South Wales, NSW）所有河口的空间淹没图层，包含2020年基准现状情景下，以及2020至2150年每十年间隔的一系列未来预测淹没情景，这些情景基于政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）共享社会经济路径（Shared Socio-economic Pathways, SSP）下的多种海平面上升（Sea Level Rise, SLR）场景，具体包括SSP1-2.6、SSP2-4.5、SSP3-7.0、SSP5-8.5中等置信度情景，以及SSP5-8.5低置信度情景。本次淹没制图依托一套完整的河口潮位站数据库、可刻画单个河口内部及河口间水位空间异质性的水面拟合方法，以及分辨率为5米的最新数字高程模型（Digital Elevation Model, DEM）。

研究通过分析每日最高水位以推导经验性超频率，进而划定一系列超阈值下的淹没范围。本数据集聚焦于相对高频的潮汐淹没事件（即年发生1天、3.6天、36.5天及182.5天的情景），而非需要更复杂水文建模的洪水事件。为分离潮汐影响，分析前已通过阈值法系统性剔除受洪水影响的水位记录。对于缺乏直接潮位观测数据的河口（无实测站河口），本研究采用水文与地貌特征相似的邻近河口的替代数据进行分析。

本数据集以每十年为间隔估算至2150年的未来淹没情景，纳入了从政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）第六次评估报告（Sixth Assessment Report, AR6）获取的、经美国国家航空航天局（National Aeronautics and Space Administration, NASA）AR6海平面上升预测工具发布的概率型海平面上升预测结果。将从适配IPCC AR6预测数据的未来海平面上升分布中随机抽样得到的海平面上升值，叠加至现有水位时间序列中。对于具备可用水动力模型的河口，本研究还通过应用河口专属调整因子，考虑了海平面上升下潮汐动力的变化（即放大或衰减效应）。

水位表面图层基于指示性超频率（年发生1天、3.6天、36.5天及182.5天）的水位超量分布构建。通过将水位表面图层叠加至由最优高分辨率激光雷达（Light Detection and Ranging, LiDAR）数据生成的5米分辨率数字高程模型，完成淹没制图。每个情景包含两类多边形图层：一类为直接淹没区（与河口水文连通的区域），另一类为孤立淹没区（海拔低于淹没水位但与河口水文隔断超过5米、但可通过雨水管网实现连通的低洼区域）。

关于文件命名规范、目录结构、形状文件（Shapefile）属性及图层说明的详细信息，已随附在ReadMe文档中。建议读者参阅随附的技术报告《新南威尔士州海岸侵蚀与淹没灾害及暴露评估——技术报告（2025）》，以获取研究方法、假设条件与建模流程的详细说明。

本数据集的核心用途是为新南威尔士州全域的战略性海岸与河口土地利用规划、早期风险评估，以及适应需求优先级排序提供数据支撑。其全州范围内的一致性便于开展跨区域暴露分析与优先级划定。不过，尽管本制图为理解潮汐淹没风险提供了科学可靠的基础，但它无法替代法定规划或工程设计所需的精细化局地洪水或淹没建模工作。