Rachel Landon says to help with future flooding events wetlands should be retrofitted into urban areas and planned for as part of new urban areas, forming a green stormwater network sleeved throughout our region. Photo / Supplied
Rachel Landon says to help with future flooding events wetlands should be retrofitted into urban areas and planned for as part of new urban areas, forming a green stormwater network sleeved throughout our region. Photo / Supplied
OPINION
Now is the time to get serious about stormwater and flood management across the region.
Flooding hazards aren’t going to go away, so we need to reduce the risk to the Hawke’s Bay community by investing in integrated solutions.
The devastation that Cyclone Gabrielle wrecked upon Hawkes’s Bay was a wake-up call about our community’s vulnerability to natural hazards, climate change, and in particular the risk we face from flooding.
Our landscape, of ranges and hills surrounding a central strip of flat land, means that the urban areas of Napier and Hastings are effectively located at the outlet of one big floodplain. Because of this, our region can’t avoid flooding, but we can change our approach to how we manage stormwater to reduce our vulnerability.
Over the years stop banks, dams, pumps, and pipes to manage and contain flood waters have been progressively engineered to address flooding risks.
As a result, much of the urban areas in Hawke’s Bay emerged relatively unscathed from the cyclone, with most of the existing stormwater and flood management infrastructure working as intended. That is, roads contained flood waters, ponds filled and attenuated flows, and stormwater pumps worked to prevent further widespread devastation.
However, the intensity and volume of rainfall from Cyclone Gabrielle were beyond the scope of what these engineered solutions have historically been designed to contain, resulting in notable failures that have devasted the lives of many people in our region.
With the severity and frequency of storms increasing due to climate change, it’s clear that the Bay can’t continue to rely upon the status quo to protect homes and communities from future flooding.
Add to this the current push by central Government to intensify our urban areas, which runs the risk of exacerbating our flooding problems if the increase in stormwater runoff from the intensification is not managed.
More resilient stormwater and flood management systems are needed that create an integrated network of stormwater and flood attenuation areas.
That network isn’t just about pipes and pumps (although they’ll continue to be an important component), but we also need to make room for stormwater to flow and pond and to make sure there is enough space for our rivers to flood in a way that avoids the areas where we live and the land our community relies on for its economic prosperity.
One way we can do this is to regenerate large-scale wetlands and basins to form part of an integrated approach to stormwater management. These wetlands can be retrofitted into urban areas and planned for as part of new urban areas, forming a green stormwater network sleeved throughout our region.
The Hawke’s Bay Regional Council has already included in its Regional Plan the goal to create another 100 hectares of wetlands in Hawke’s Bay by 2040. Action is now needed to turn this goal into reality, not only will this result in a more resilient approach to flood management by providing much-needed areas to attenuate flows, but it will help to improve water quality and ecological biodiversity within our region.
With careful design, we can continue to grow our existing urban areas logically and cohesively and achieve more effective stormwater outcomes.
A resilient stormwater and flood management system will not be cheap; stop banks need to be repaired and raised, land will need to be set aside for overland flow paths, widening stream corridors, wetlands and basins.
To provide these solutions our region needs a more cohesive approach when managing the impact of urban growth, adapting to the impacts of climate change and planning for flood management across both our existing communities and in areas where new development is planned.
* Rachel Landon is a chartered engineer with over 20 years of experience in project delivery. Landon is the principal Three Waters engineer for Development Nous where she helps to lead the Civil Engineering team with other chartered and senior staff. She takes an active interest in the management of community assets and is particularly interested in the linkage between policies, strategies and how infrastructure is procured.
