2D modelling of stormwater in Auckland city - Lessons learnt

Due to recent advances with hydraulic modelling packages and the availability of LIDAR (light detection and ranging) survey data, the application of two dimension al (2D) modelling techniques to better represent surface flow behaviour and flood extents in hydrodynamic models is increasing. The purpose of this paper is to contrast the methods used and results gained from flood risk assessment projects utilising one dimensional (1D) hydraulic models coupled with a 2D model component. Examples used are part of studies undertaken by AECOM on behalf of Metrowater and Auckland City Council in recent years. This paper describes the differences in processes used in the development of the models, the advantages and disadvantages of each, the instabilities encountered and the difference in the types and nature of results achieved. The lessons learned from the projects are discussed, which can be applied to future projects.

Key areas described in the paper are model conceptualisation, model development, instabilities encountered, model run times achieved, issues found and how they were dealt with, along with how results were interpreted and validated. The paper shows how each project is unique and the catchment characteristics that need to be considered when identifying the optimum modelling methodology.