Long Bay Development - Benefits of Coupled Modelling

In certain complex situations, 1D models are less suited to reliably predicting actual flow and flood behaviour during larger storm events. A key advantage of coupled 1D-2D models is the closer spatial representation of the true physical catchment, thereby simulating flow behaviour with greater accuracy.

Extensive Environment Court proceedings have advanced the Structure Plan for one of Auckland’s largest and original water sensitive communities at Long Bay. The Structure Plan area is over 380ha providing some 2500 dwellings and a town centre. This includes 25ha of the lower Awaruku Stream catchment undergoing significant landform changes to provide civil infrastructure, in particular, the creation of a large 2ha wetland within an existing flood affected area. This retrofit system provides quality treatment for 180ha of non-greenfield catchment.

This paper presents a unique and complex stormwater case study problem, explaining the use of current technologies (GIS, LiDAR, terrestrial survey and 3D land surface modelling) to produce a detailed integrated model used as both a hydraulic analyses and a design tool.

Coupled models require quality data and this project highlights a positive partnering between consultant and Council facilitating the use of a single hydraulic model, encouraging innovation and optimisation of Community Assets.