Retreating from the coast, and the riverbank

A recent news item told us that the residents of Westport are talking about moving their town inland. Nobody wants to have to move, but this is solid thinking. The majority of New Zealanders are exposed either to coastal inundation, or river flooding, or both, and the likelihood of both are on the rise. As the RNZ story pointed out, when we are thinking about infrastructure (roads or homes or public facilities) we need to think on the 50-100 year time scale and the effects of the changing climate must be taken into account.

Whether it’s a new house, a new walkway or sports field, or a new office block, we need to consider whether rising seas or more frequent and bigger floods will render it useless or destroy it completely over the course of this century. We are not used to thinking this way as the climate hasn’t changed much, and the seas haven’t risen, for thousands of years – but those days are gone. When I go to the beach near my home on the Kāpiti Coast and see the row of houses built just above the high-tide mark, it’s a struggle for me to say to myself that they will all be gone in 100 years. Even though I know what the evidence tells me. The reality is that unless we take action ourselves, the waves and the water will take the action for us.

Fortunately for New Zealand, we have a great deal of land and recreational space that is far above sea level and not exposed to river flooding. Our task over coming decades is to make the most of that space, and move away from increasingly risky zones on our sea shores and river banks.

Dr James Renwick

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