The Waimakariri River once flowed through Christchurch, forming an area that is rich in deep alluvial soils with interspersed peaty soils and coastal sands.
These diverse soil types once supported a variety of ecosystems including impressive podocarp forests, and abundant freshwater springs which formed the various low gradient streams and extensive wetland networks.
The abundant freshwater springs throughout the zone support a network of low gradient streams and rivers including the Avon/Ōtākaro, Heathcote/Ōpāwaho, Styx/Pūrākaunui and Ōtūkaikino and catchments.
A number of peaty wetlands occur in historic back swamp areas including Travis Wetland and the Sanctuary wetlands, which is the largest wetland area on the lower Waimakariri River. The Avon-Heathcote Estuary/Ihutai and Brooklands lagoon are the two largest examples of these habitats within the zone.