Flood Extent 10 Year (OpenData)

This entity describes how far floodwaters could spread during a '1-in-10-year flood'. A '1-in-10-year flood' means there is a 10% chance of that level of flooding happening in any given year. Similarly, a '1-in-50-year flood' has a 2% chance of occurring in a year. These probabilities are based on long-term weather and tide records. We also adjust the data to account for future changes in rainfall and sea levels due to climate change. To estimate flood areas, we use computer models that simulate how stormwater flows through Christchurch’s drainage system. These models test different rainfall durations—from short bursts (30 minutes) to long storms (up to 60 hours). For each flood scenario, the model calculates the deepest flooding expected, the largest of which becomes the final flood extent shown in the data. This flood extent data is used in a derived model called drvFloodExtent, which combines flood models for all catchments and scenarios and is intersected with Rating Units to generate Property Condition comments on the LIM. Any updates to the flood extent data need to be synced to the derived model to appear on the LIM. It is spatially abstracted to: Area. Entity Type: Event.本数据集实体描述了十年一遇洪水（1-in-10-year flood）发生时洪水的可能蔓延范围。所谓“十年一遇洪水”，即任意一年内该等级洪水发生的概率为10%。同理，50年一遇洪水（1-in-50-year flood）的年发生概率为2%。上述概率基于长期气象与潮位观测记录推算得出。同时，我们针对气候变化引发的未来降雨与海平面变化对数据进行了校正。为估算洪水淹没范围，本数据集采用计算机模型模拟雨水在基督城排水系统中的径流过程。这些模型会测试不同降雨历时场景，涵盖从短时强降雨（30分钟）到持续性长暴雨（最长60小时）的各类工况。针对每一种洪水情景，模型会计算预期的最大积水深度，取其中极值作为本数据集最终呈现的洪水淹没范围。该洪水范围数据将被应用于一款名为drvFloodExtent的派生模型中，该模型整合了所有集水区与各类情景的洪水模型，并与物业评级单元（Rating Units）进行空间叠加分析，以在土地信息备忘录（Land Information Memorandum，LIM）中生成物业状况评述。若需更新洪水范围数据，需同步更新该派生模型，方可在土地信息备忘录（LIM）中展示更新后的内容。本数据集在空间维度上抽象为：区域。实体类型：事件（Event）。