KEY POINTS:
Ask yourself this question: How natural is a natural hazard such as a flood when the settlement affected is built on a flood plain?
Take as an example the Far North town of Kaeo, which was flooded three times last year - in February, in late March and again in July. The town suffered again in February this year, when 200mm of rain caused landslips, downed power lines and closed roads.
Things are not much different elsewhere in the region, including the communities of Kaihu and Kaitaia in the Awanui River catchment and, in particular, in the region's main town, Whangarei.
Some people will remember the serious flooding in Whangarei in 1999. But one lesson is that memories are short and selective.
We do not remember extreme events for a great length of time. The further we get away from the floods, the more likely we are to think the risk is small.
Severe flooding occurred again in Whangarei in April last year, causing an estimated $80 million in damages. A similar amount was spent by central government for road repairs and the clean-up. About $1.2 million is being spent on flood protection works at Kaeo, Kaihu and Kaitaia over the next 12 months, which is on top of about $1.5 million spent there since 2005.
But the residents of these communities may have unrealistic expectations of flood risk and what can be done to change it. Much can be learned from the lesson of the Northland towns, as their circumstances are similar in communities throughout New Zealand.
The damaging effects of natural hazards such as floods and storms are often called "acts of God". This implies natural hazards are accidental and that they are simply physical phenomena outside of society.
In the lesson of Northland, the key questions to ask are: How natural is the flood hazard? How natural is the risk? What are reasonable management options? In finding answers, these are the points to keep in mind:
* A flood that does not affect human beings directly or indirectly is a natural phenomenon but not a natural hazard.
* A flood hazard has an element of human involvement. Living in a flood-prone area is voluntary. As a result of earlier flooding, the places affected by floods are generally known.
* If human activities can cause or aggravate the destructive effects of natural phenomena, they can also eliminate or reduce them. The risk from flooding anywhere is a function of a natural rain event and human vulnerability to that event. The latter is a product of social, political and economic behaviour.
Vulnerability to flood loss is generated by occupying flood-prone land. On the other hand, areas at risk from flooding often offer considerable benefits for farming, such as fertile alluvial flood plains or low-lying land in valleys.
Managing the effects of floods can be achieved in any or all of four ways - structural protection, compensation, regulation and relocation.
The costs and benefits of structural protection measures such as stopbanks, flood dams and channel straightening are fraught with problems that need to be carefully considered.
These measures prevent the river in peak flow flooding naturally into depressions which detain water, releasing the flow in the river, thus preventing the river reaching danger levels further downstream.
A problem with large-scale investment in and reliance on structural protection measures to ameliorate the impact of flooding is that they can induce a false sense of security.
The compensation option raises issues related to fairness and freedom of choice. Should a homeowner who lives on a flood plain reasonably expect to receive reparation from the Government when the inevitable deluge occurs?
The expectation of government aid distorts the true climate resource potential of an area or region.
What is an unacceptable risk in one place, where there is no chance of government relief when a flood occurs, may turn out to be quite an acceptable risk at the same place where there is an expectation of financial bailout or government compensation package.
Relief aid generally works to ensure the same people and areas will be affected again and again, since it discourages taking action to avoid, reduce or mitigate future events.
A "free market" option is to make flood insurance mandatory with the view that insurance premiums will work with market forces of cost-benefit.
Typically regulation and relocation are the preferred flood management tools.
Where the flood damage risk is clearly high, people could be guided towards adopting appropriate land use practices. Land could be classified according to flood risk and land use, regulating land use accordingly, such as re-zoning commercial and residential land as recreational and replacing buildings with parks and golf courses on flood-prone land and relocating flood-sensitive activities.
Clearly, there are many lessons to be learned from Northland's experience. They point to a number of practical policy measures that can be promoted to manage risk. Otherwise, the costs of flooding disasters will continue to grow.
