Overland Flow Paths

Overland flow paths (OLFPs) were re-mapped for the Auckland region in 2019 by WSP using LiDAR data flown in 2016 and 2017. The OLFPs were re-mapped using a 1m DEM formed from ground points. Nearly 6,000 manual adjustments to the DEM were used to map the overland flow paths in flat and depression areas. OLFPs were identified using GIS techniques and are not based on hydraulic modelling. Peak flow rates and runoff volumes for 2-, 10- and 100-year annual recurrence interval (ARI) and 90th and 95th percentile events have been attributed to each overland flow path, following the graphical method outlined in Guidelines for Stormwater Runoff Modelling in the Auckland Region: Technical Publication 108 (TP108). Both the existing scenario (existing imperviousness and rainfall) and the future scenario (future development and rainfall due to climate change) are represented here; two climate change scenarios were considered, viz., temperature increases of 2.1 and 3.8 degrees-C. The aim of this dataset is to provide a regionally consistent validation tool for runoff calculations and hydraulic modelling to assist consultants, contractors, development engineers, catchment managers and hydraulic modelling staff. A copy of the full background report can be obtained from the Regional Planning team in Auckland Council’s Healthy Waters department. The data will be updated on an ad hoc basis to align with updates to Auckland Council’s LiDAR data. Vertical Datum: NZVD19462019年，WSP公司利用2016年与2017年获取的激光雷达（LiDAR）数据，对奥克兰地区的坡面流路径（Overland flow paths，OLFPs）完成了重新绘制工作。本次坡面流路径的制图基于由地面点生成的1米分辨率数字高程模型（Digital Elevation Model，DEM），通过对该DEM进行近6000次手动调整，完成了平缓区域与洼地区域的坡面流路径精准制图。研究团队采用地理信息系统（Geographic Information System，GIS）技术识别坡面流路径，未依托水力学模拟开展相关识别工作。参照《奥克兰地区雨水径流模拟指南：技术出版物108（TP108）》中所述的图解法，为每条坡面流路径赋予了2年、10年、100年年重现期（annual recurrence interval，ARI）降雨事件以及90%、95%百分位降雨事件对应的峰值流量与径流量。本数据集涵盖了现状情景（现状不透水面积与降雨条件）与未来情景（因气候变化引发的未来开发与降雨条件）两类场景；共考虑了两种气候变化情景，即气温分别升高2.1℃与3.8℃的情景。本数据集旨在提供一套区域统一的径流计算与水力学模型验证工具，以辅助咨询机构、承包商、开发工程师、流域管理者以及水力学建模人员开展相关工作。完整背景报告可向奥克兰理事会健康水务部门的区域规划团队申请获取。本数据将根据奥克兰理事会激光雷达数据的更新情况进行不定期更新。垂直基准面：NZVD1946（新西兰1946年垂直基准面）