Your Council

Natural Hazards FAQs

This page contains answers to frequently asked questions about natural hazards.

What is a natural hazard?

Natural hazards are those random events Mother Nature sends our way from time to time, including earthquakes and extreme weather events such as storms, floods and landslides.

Why should we be concerned?

Several fault lines run through our district, and the Canterbury earthquakes have shown we can never be sure when ‘the big one’ may strike.

Climate change impacts are potentially a major threat for Kāpiti.  Globally there is increased risk of flooding and erosion from more intense storms and a predicted rise in sea levels caused by a combination of melting ice and the expansion of the water as it warms.  Coastal communities like Kāpiti are more vulnerable than most.

What is known about climate change?

Most climate experts agree average global temperatures are likely to rise by 3–4°C by 2100, unless the world reduces greenhouse gas emissions.  Polar regions will experience much greater warming than equatorial regions, causing ice to melt and sea levels to rise.

Don’t scientists disagree on whether climate change is happening?

No. Ninety seven percent of all climate science experts agree this is happening. There is more agreement on this issue than on almost any other science matter for centuries.

What are scientists saying about rising sea levels?

Ice sheet and ocean scientists project sea levels will rise about 1m by 2100.  Rises of up to 2m cannot be ruled out depending on how the climate system reacts.

Melting ice sheets are contributing to sea level rises and this may continue over time at approximately 1.5 – 2m per century.

How much the sea will rise will depend largely on how much the world can reduce its greenhouse gas emissions.

How could Kāpiti be affected?

Up to 2400 properties may be affected by coastal erosion and/or storm damage over the next 100 years, some a lot sooner.  This represents about $2.2 billion worth of assets.

About 21km of local roads are at risk, along with an estimated 67km of pipes and 27 pump stations in the water supply, sewerage and stormwater networks. Some Council services are located seaward of properties, so in a major storm event some properties could lose access to services before the land or buildings suffer damage.

Parts of SH1 and the North Island main trunk railway could become unusable later this century.  The area between the Ames St/SH1 intersection and Fisherman’s Table restaurant and further south is at particular risk.

Rising water tables could affect underground pipes and cables, and soils and water tables within a couple of kilometres of the coast. Coastal septic tanks and water supply bores could eventually be contaminated by sea water.

What are scientists saying about rainfall?

As air temperature rises, the amount of rainfall during single events will increase because warm air holds more moisture. Storms generated at sea will be more intense because greater energy is released from a warmer sea.  Coastal communities like Kāpiti will experience more violent storms.

What would be the effect of extra rainfall?

Current storm water networks and river flood protection works won’t cope.  Pipes and culverts will overflow and create bottlenecks resulting in new flow paths.  Stop banks will overflow during big events.

Some roads and reserves will need to be used as secondary flow paths during floods. This means they won’t be available for access and recreation.

The frequency and severity of the impacts on some properties might mean they need relocating. In other cases measures such as raising floor levels could be required.

What is Council doing about this?

Council has identified that approximately a third of Kāpiti’s homes are located in a flood plain that is susceptible to a 1 in 100 year flood.

It has produced new stormwater management plans based on 16% extra rainfall.

In August 2012, Council completed a coastal hazard assessment, as required by Government. It included shoreline projections within 50 and 100-year timeframes. This information has been used in the development of policies and rules in the Proposed District Plan.

Council is legally required to ensure new buildings and developments are out of harm’s way or that the risks are eliminated or managed. To help combat the hazard risks there may have to be changes to District Plan rules on where development can and can’t take place. District Plan provisions are currently being reviewed and will be notified for submissions around November 2012.

What are the implications for the proposed Expressway?

Natural hazard issues, including flood control and respecting natural storm water flows, are well known to the Expressway’s design team.

Council is working to ensure construction of the proposed Expressway through the flood plain won’t aggravate flood issues in the district.

What are the implications for Council’s supply from the Waikanae borefield?

The new bores being drilled are well inland. Those nearest the coast will be closed to avoid salt water contamination.