Flood Extent 50 Year (OpenData)

This entity describes how far floodwaters could spread during a '1-in-50-year flood'. A '1-in-50-year flood' means there is a 2% chance of that level of flooding happening in any given year. Similarly, a '1-in-10-year flood' has a 10% 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.本数据集描述了“50年一遇洪水”发生时洪水可能蔓延的范围。“50年一遇洪水”指任意一年内发生该量级洪水的概率为2%；同理，“10年一遇洪水”的年发生概率为10%。上述概率基于长期气象与潮汐观测记录推导得出。我们还针对气候变化导致的未来降雨与海平面变化趋势，对数据集进行了校正。为估算洪水淹没范围，我们采用计算机模型模拟暴雨径流在基督城排水系统中的流动过程。该模型可覆盖不同降雨时长的场景，从短时强降雨（30分钟）到持续长时风暴（最长60小时）。针对每个洪水情景，模型将计算预期的最大洪水深度，其中的最大淹没范围即为本数据集展示的最终洪水波及范围。该洪水波及范围数据将用于衍生模型drvFloodExtent：该模型整合了所有集水区与情景下的洪水模型，并与评级单元（Rating Units）进行空间叠加分析，以生成土地信息备忘录（LIM）中的物业状况说明。若更新洪水波及范围数据，需同步至该衍生模型，方可在LIM中体现更新内容。本数据集在空间维度上抽象为：区域。实体类型：事件（Event）。