River Catchment Flood Models Hazards

The models have been prepared by consultants on behalf of Council. A total of seven catchment flood models were prepared to inform the maps. Tonkin & Taylor updated five of the models in 2021 and Orphanage/Orchard again in 2023 and these were peer reviewed by consultants Stantec and WSP Opus. WSP Opus updated two of the models in 2020 which were peer reviewed by Stantec in 2021. The flood model maps are available online at www.nelson.govt.nz, along with an explanation of the terms and scenarios. River flooding layers show areas modelled as flooding in a 1% AEP present day flood event and in a 1% AEP flood event in the year 2130. The floodway shows the main channel that carries floodwater. While usually aligned with natural channels, floodways can include artificial watercourses. Blocking a floodway can change floodwater flows, damage riverbanks, and increase flood levels.

本批流域洪水模型由顾问受议会委托编制完成，共计7个，用于支撑相关洪水风险图的制作。Tonkin & Taylor于2021年更新了其中5个模型，并于2023年再次对Orphanage/Orchard相关模型进行更新，上述更新工作均由Stantec与WSP Opus两家咨询机构完成同行评审。WSP Opus于2020年更新了剩余2个模型，该批次更新内容于2021年由Stantec完成同行评审。相关洪水模型风险图可于官网www.nelson.govt.nz在线获取，同时可查阅对应场景的术语说明与情景解释。河道洪水图层展示了当前情景下1%年超越概率（Annual Exceedance Probability, AEP）洪水事件，以及2130年情景下同等年超越概率洪水事件的模拟淹没区域。行洪道（floodway）图层标注了承载洪水的主河道，尽管行洪道通常与天然河道走向一致，但也可包含人工水道。堵塞行洪道会改变洪水径流路径、损毁河岸并抬高洪水位。