New and valuable information about where water might pond around Hamilton in heavy rain and extreme events, is now available for residents to understand rain effects on their property.
This new update – result of two years of technical investigation and review, adds ‘flood depressions’ to the city map, identifying areas around Hamilton that have the potential to fill up with water when pipes and culverts are blocked, where there is simply too much water, or where there are no stormwater pipes to carry water away.
Hamilton City Council is making the data available on its public Floodviewer tool; a city map which helps residents understand rain effects on their property.
“Think of them like bathtubs,” said Council’s Stormwater Infrastructure Engineer, Andrea Phillips. “If a pipe or culvert gets plugged by debris or other items, or there is simply too much water for the systems to cope with, the water will pond until it can be released or fills the depression.”
This scenario, although rare, was seen in the Auckland Anniversary Weekend floods of 2023, as torrential rain resulted in blockages to pipes and culverts. Understanding what might happen in a similar rare event in Hamilton helps Council, and homeowners, plan for the future.
Hamiltonians can visit Floodviewer to find out how their property or home could be impacted by flooding. Tips to prepare their property can be found at getready.govt.nz but simple steps include keeping their home’s drains free from debris, leaves and rubbish (if safe to do so). Securing loose items when heavy rainfall is predicted can also help to minimise the chance of these items being washed downstream to block a pipe or culvert.
Around a third of properties in Hamilton have some of their land within a flood depression area (mostly properties around the city’s extensive gully system) and for most the flooding in the modelled scenario is minor or restricted to only a part of the land.
Most of the properties with higher potential flooding will have previously been advised by Council as part of its wider flood mapping work. For added assurance, Council is writing to about 650 properties which have a potential average of a metre of flooding, or more, at a building footprint) in the modelled rare event.
This will inform those potentially-affected properties and means there will be cases where nearby properties, even in the same street, don’t receive a letter because the modelling is under the one metre average. Regardless of the flooding depth chosen, there will always be properties which fall just outside the benchmark, but all properties have individual data available on Floodviewer.
– from NewsViews
