Hydraulic and Hydrological Modelling for Complex Design in a Peat Area

Addison Development is an 80ha development in Takanini, South of Auckland. This area is well known as a peat area with the unique geological characteristics of flat contours, high ground water table and peat soil substrate. The development in this area is a challenge in terms of stormwater management due to the complex site constraints.

This paper primarily focuses on the application of hydraulic and hydrological modelling as a robust tool to aid the comprehensive stormwater management design for the 4th stage of Addison Development. The design consists of 42 raingardens and a reticulation network with pipe sizes up to 2300mm diameter for stormwater treatment, detention and conveyance. HEC HMS model was used at the preliminary design stage to investigate the practicability of using raingardens for the stormwater detention function. During the detailed design stage, MOUSE (MIKE URBAN) model was used to optimise the size of the reticulation network and to simulate the peak water levels in various rainfall events. The advantages of each modelling tool are also discussed in this paper.