Halswell Domain

Halswell Domain
View from the Model Engineers' site in the Halswell Domain

Thursday, August 19, 2021

Seeing the benefits of flood protection

By Anne Galloway and Chrys Horn


We’ve seen some big floods around New Zealand over the last couple of months – one of them right here in Canterbury in early June when record amounts of rain fell in some areas, breaking the drought that we had had up until that time. 

As our city grows, our houses get bigger and our yards get more asphalted, there are few places for the rain to go.  For those living in the lower reaches of the Ōtākaro/Avon and the Ōpāwaho /Heathcote rivers, having the water rushing off the hard surfaces and into our river systems has been increasingly problematic.  Add to that that we are a low lying city that is part of the Waimakariri River flood plain, that became even lower in places during the earthquakes and it is clear that flooding is one of our greatest risks as a city.

For some years now the Council has been putting in infrastructure to ensure good amounts of green space and water retention.  We’ve seen a lot of these facilities going in around Aidanfield, Wigram, Nga Puna Wai, Longhurst, Knights Stream, Kennedys Bush and in Hendersons Rd - Cashmere Rd - Sparks Rd area.  Some of them have also become increasingly attractive areas for walking and biking as the planting takes hold and gains height – the Quarry and the Sparks Road Wetland are examples.  Some areas are still being built.

Our last flood tested this infrastructure and over all the Council are very pleased with how the retention areas around Halswell worked.   While some flooding occurred along Sparks Road where construction of retention areas is still in progress, millions of litres of water were held back in areas where the water was meant to be held and places that often flood (Hendersons road between Sparks and Cashmere Road, for example) did not.


Along with protecting the new housing going on in the area and protecting those in the lower reaches of the Ōpāwaho Heathcote, all this development has some added amenity benefits (as the walkers and bikers in our new wetland areas will attest) and will capture a lot of sediment thus improving water quality in the Ōpāwaho river system – something that will make life better for the plants, insects, fish and eels that live in the river.    

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