Stormwater Management - Urban Aquatics
The Urban Aquatics Group works with all aspects of urban stormwater management and monitoring and is based at NIWA's Auckland office with two field hydrologists at Bream Bay.
Group Manager Dr Jacquie Reed takes sediment samples from mudflats of the Upper Waitemata Harbour.
The view from Kemp House on 29 March 2007 showing rising floodwaters which threatened the historic buildings.
Floodwaters reach the steps of the Stone Store, 29 March 2007. Note how the bridge acts as a dam.
The group specialises in water quality and flow monitoring and modelling. We regularly work with scientists across NIWA to investigate the impacts of urbanisation on urban receiving environments such as streams, estuaries and harbours.
These pages contain examples of our work past and present as well as contact details.
News Bulletin: Group members help safeguard historic buildings
Bream Bay group members Ben Harding and Graeme Mackay have been able to warn the New Zealand Historic Places Trust (NZHPT) that Kemp House and the Stone Store, Kerikeri were at risk of flooding twice in the last four months. Widespread flooding hit Northland in late March and again in July 2007. The floodwaters in March were dangerously close to the historic buildings. Kemp House, also known as the Kerikeri Mission House, was built in 1822 and is the oldest European building in New Zealand. Next door is the Stone Store built between 1832-36. Both buildings were badly damaged in the Kerikeri Flood of 1981 causing over a million dollars worth of damage and are periodically threatened by floods.
The NIWA flood warning system is based on telemetered rainfall and water level recorders upstream in the Kerikeri catchment. The forecasting system has been upgraded and automated over recent years, and a computer modelling system called TOPNET, was installed in 2003. Preliminary warnings can be issued for the Maungaparerua sub-catchment (12 km upstream) and a second warning based on a forecast level on the Kerikeri River. This second level is the basis for a definite evacuation alarm for Kemp House. Warnings can be given up to 48 hours in advance.
On 29 March 2007, the river reached the second warning level, the largest flood since 1981. NIWA sounded the alarm and NZHPT decided to evacuate their irreplaceable ground floor displays. Accurate flood levels at this stage are difficult to predict because of the damming effect at the nearby bridge (as can be seen below), and the waters came within 200mm of the ground floor proving the value of the NIWA flood predictions.
While still an extreme event, the July 10 floodwaters posed little risk to the buildings and the exhibitions were not evacuated.