Stormwater Management and Flood Mitigation in the Meola Catchment, Auckland

Auckland Council established the Central Auckland Stormwater Initiative (CASI) to investigate options to alleviate flood hazards and address other stormwater management issues in central Auckland, which includes the Meola, Oakley and Epsom catchments among others. A series of CASI technical workshops resulted in the identification of probable high-level solutions to address flooding. This paper provides background on flood issues in Meola and details stormwater management and flood mitigation options.

The Meola drainage system is a complex combination of Meola Creek, wastewater pipes, stormwater pipes, combined stormwater/wastewater pipes, and public and private soakage systems. Flood issues in the Meola catchment, including habitable floor flooding are commonly associated with topographical depressions, lack of available soakage for stormwater disposal, limited drainage network capacity and contaminated flooding.

Functional requirements for flood solutions considered the influence of growth, future climate change on rainfall patterns, the extent of soakage sensitivity on flood issues, and geological conditions on construction techniques. Furthermore, geological conditions and topography in the Meola catchment play a significant role in the design and costs of the stormwater issues and options.

Stormwater management solutions considered a number of options including improved soakage systems, increased stream conveyance capacity, low impact design options, increasing stormwater storage capacity, stream daylighting and large-diameter stormwater tunnels.