Environment Waikato is factoring climate change into its river management planning, last week’s Catchment Services Committee meeting heard.
Natural Hazards Programme Manager Brendan Morris said managing hazards in the Region was changing as a result of increasing demand for development on flood plains, climate change, increasing community expectations for flood protection and recent flood events which had highlighted New Zealand’s vulnerabilities to flooding. Changes in civil defence management had also led to an all-hazards approach and requirements for a greater co-ordination of risk reduction activities.
Climate change worsened the effects of river flooding, he said. Recent floods in the Manawatu and Bay of Plenty had clearly illustrated the limitations and risks of structural flood protection measures and that the impacts of river flooding was of national significance.
Over the next two years Central Government was reassessing its role in flood risk management to find ways of managing floods better. It would cover whether current flood risk assessment was adequate, future best practice, funding and affordability for poorer communities, legislation on managing flood risk and river control, getting good information on flood risk and the role of local and Central Government and communities in flood management.
A Regional Council group is working on a flood management protocol designed to develop better processes for assessing flood risks and selecting mitigation options, understanding natural systems, increasing the level of community awareness and treating residual risks.
A wide range of social, environmental, economic and cultural effects are expected as a result of climate change, including more frequent and intense storm events. The increased frequency of flooding and rainfall intensities are likely to increase between 5 and 15 percent, and there would be more pressure on existing flood protection schemes.
Sea level rise would also increase coastal erosion and flooding, particularly with storm surges, with worse flooding in delta regions of major rivers, he said.
The Council was now looking at greater than 100 year events, evaluating one in 500 year events, tsunami and earthquake risks.
Cr Jenni Vernon said the two major floods last year in the Manawatu and Bay of Plenty, along with the Asian tsunami had woken Central Government up to the risks of climate change.