An Innovative Approach to Flood Hazard Mapping in Hamilton City

Hamilton City Council (HCC) recently embarked on a Three Waters Modelling program to better understand the potential risks and hazards relating to the water, wastewater and stormwater networks. In terms of stormwater, this has meant developing an understanding of flooding potential across the whole city, and identifying areas of potential high risk hazards to enforce development and planning constraints and red flag areas.

In order to achieve a cost effective solution across the whole city an innovative approach was developed by AECOM and Hamilton City Council. The approach that has been adopted included a rapid flood hazard model covering the city. The outputs from this model were then used to quantify the number of affected properties in each subcatchment. Performing a cost benefit analysis between the model build cost and the potentially affected properties identified areas of benefit for detailed modeling.

This paper describes the model’s conceptualisation and development. It explains the methodology used to deliver the project on time and budget while achieving the required outputs. It also discusses the limitations of certain aspects of the results and the potential advancements that could be made for marginal additional cost. Finally, it examines the lessons learnt and how they can be applied to future projects.