Castles in the Sand

Sand 1

By Christine Rose, Christine’s Environment Column, Mahurangi Matters, March 2014.

Despite credible international science proving that climate change is human-induced, Governments and the public have been slow to acknowledge the scale of the threats we face. Not only are we collectively failing to anticipate or respond to climate change, but we’re doing little to address its causes. We are exacerbating the problem and failing to provide preventive or protective measures to deal with its effects. Our vulnerability seems high, while our adaptive capacity seems low.

Increased climate variability and extreme weather events, bizarre temperatures, and damage to land and property are the new reality. But we continue to develop and occupy marginal land. We drain swamps, bulldoze sand dunes, build on low-lying land and remove all buffers to the weather. Deregulated land development and building means that almost anything goes, anywhere. Dwellings on steep slopes; on flood plains; cliff tops and sandspits just metres from the beach? Let private property rights prevail.

When councils do attempt to apply precautionary notations on property titles, land owners are appalled; apparently concerned more about their property values than about damage to property from climate change. But when storm events do damage property, costs are socialised through the Earthquake Commission (for landslides etc) or increasing insurance premiums. As insurance companies come to reject climate claims, costs will increasingly fall on homeowners and ratepayers.

Some land should not be built on but should be retained for flood attenuation, or buffers against storm surges and rising seas. Urban coastal development in areas which were recently swamps and sand dunes will be increasingly prone to erosion and damage as previous buffer land is washed away, but particularly in conditions of climate extremes like regular “higher than usual” tides and adverse storm events.

Given the long life of residential and commercial buildings and infrastructure, and the clear prospect of worsening extreme weather conditions, planners would be right to advise development caution. We should also be concerned at the loss of other values such as inter-tidal ecosystems, salt marshes and beaches, as well as culturally and historically significant sites which are often overlooked or understated. The natural character of the coast is also at risk as we seek to engineer hard solutions to worse weather.

Some recommendations for mitigating climate change impacts include “managed retreat” as development is withdrawn over time; adaptation, where buildings and infrastructure are retrofitted (ie lifted or moved) to avoid storm pressures; or defence – hard structures like sea walls. But much development is fixed already. Councils seem reluctant or powerless to stop new development in marginal areas. But they’ll be liable for costs for failing to prevent it. Councils and communities will pay for others’ views, access and ultimately their vulnerability to the rising sea.

The Christchurch earthquake recovery provides opportunities for a managed adaptation to climate change. For most other areas, the problems will be with us for a long time to come.

Published 5 March 2014

Comments

  1. One does wonder whether we should continue to build in Omaha – which seems very vulnerable to even a slight rise in sea level.

    Any ideas on how flood protection will work for this community over the next 50 years, all options would seem to have quite a high environmental impact.

  2. Roger Grace says:

    Floods as such may be a problem for Point Wells, Whangateau, and inner Omaha residents, but the big problem for those on the beach front will be erosion. With severity and frequency of storms set to increase with climate change, and exacerbated by creeping sea level rise, erosion events on the main beach will become more severe and more frequent. If the rock groynes at the north end of the beach are well maintained and eventually built a bit higher they should minimise beach front erosion but will not stop it. You may recall back in the early 1970’s a wooden seawall was put along a large section of beach. It lasted a few seasons and was eventually smashed to bits by storms. One problem is that when the subdivision was first put in place the developers bulldozed the foredunes flat so there would be good sea views from the front sections! This of course removed a large quantity of sand which was an important buffer against periodic erosion. Without sufficient volume of sand the low foredune retreated far more than it would have with its original sand volume. I believe a few houses actually got demolished.

  3. Roger Grace says:

    Maintaining a good population of foredune plants like Pingao and Spinifex will also help by binding sand and encouraging sand accumulation. They will minimise erosion but will not stop it. They also help recovery of the foredune after a storm. They are a “soft option” and preferable to a hard engineering option of a seawall or sloped rip-rap rock. Hard options can in fact increase erosion by reflecting high-energy waves, which carry sand back down the beach.

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