What is flooding?

It is hard to define flooding simply. For Council’s flood planning and management purposes, flooding is defined as:

Relatively rare and high water that overtops natural rivers, creeks or artificial channels and / or overland flows resulting from:

Flash flooding is flooding which is sudden and unexpected.

Floodplains are lands that have been formed by flooding over time. Much of Newcastle has been built on floodplains. This was evidenced in the floods of June 2007.

Floodprone land is all land that would be affected by the highest conceivable flood that nature can produce. Only land that is above these levels is truly flood free.

The insurance industry has its own definitions of flooding (and stormwater) and you should make your own enquiries about how your insurance company classifies flooding (and stormwater), and how this relates to your insurance provisions.

Local drainage is only designed and intended to manage lesser and more frequent rainfall events. Local drainage problems can occur anywhere and are not included in Council’s floodplain management planning.

What is Floodplain Management?

Floodplain Management is making balanced decisions about the economic, social and environmental costs and benefits of allowing a broad range of activities to take place on a floodplain.

There are many different aspects of floodplain management. These include:

• Calculating flood information such as heights, extents and potential risks to life and property of flooding, including estimating the effects of possible future climate change and sea level rise.
• Finding and evaluating complete systems of managing the risks, which would include consideration of emergency management, examining if it is feasible to reduce the flooding, looking at ways of living with the risk, and how to manage future development
• Consulting with the community when planning for floods
• The elected Council adopting a Floodplain Risk Management Plan.
• Finding the funding and resources needed to implement this Plan over time.

Why does flooding occur?

Flooding can result in property damage and even loss of life. Newcastle and its suburbs was built on natural floodplains so from time to time during times of very heavy or extreme rainfall, nature reclaims these areas.

Who is responsible for managing floods?

Flood management is a shared responsibility.

Management of large scale (and generally rare) flood events is a shared responsibility between Government and the community.

The NSW Government Floodplain Development Manual states: “The management of floodprone land is, primarily the responsibility of Councils”, but adds that other agencies such as the NSW Department of Planning and the NSW State Emergency Service have important and complimentary roles.

Councils are responsible for the preparation of Floodplain Risk Management Plans and the SES (as the combat agency for dealing with floods) for the preparation of Local Flood (emergency) Plans, and in the management of floods when they occur.

In addition, YOU – owners and occupiers of flood prone properties - are required to play a significant role in flood awareness, preparedness of your property and appropriate flood response.

Can flooding be removed from Newcastle?

Flood proofing Newcastle by attempting to prevent floodwaters from entering the floodplains on which much of Newcastle has been built is an impossible task. The city’s drainage system was only designed to cope with frequent rainfall. Trying to build a drainage network to prevent flooding in Newcastle would require massive changes to the city that would make many suburbs unrecognisable.

This is not a reasonable solution as it would severely affect the suburb’s business district and would probably transfer the problem downstream.

Is my property flood affected?

Only land that is higher than all future possible floods is completely flood free. Many properties which were not flooded in June 2007 may be flooded in different floods in the future. To find out if your property is potentially flood affected, apply for a Flood Information Certificate.

What is the probable maximum flood (PMF)?

The PMF is the largest flood that could possibly occur. It is a very rare and improbable flood. Despite this, a number of historical floods in Australia have approached the magnitude of a PMF. Every property potentially inundated by a PMF will have some flood risk, even if it is very small. Other properties may have an extreme risk to life at the PMF where buildings could be washed away with little or no warning, and people trapped inside would most likely perish.

The NSW Government Floodplain Development Manual requires all possible floods up to and including the PMF to be considered in floodplain planning. It states:

“The PMF … provides an upper limit of flooding and associated consequences … . It is used for emergency response planning purposes to address the safety of people.”

History has shown that extreme flood events can and do happen (e.g. the 1990 flood in Nyngan, the November 1996 flood in Coffs Harbour, the August 1998 flood in Wollongong, the 1998 flood in Katherine, QLD’s Central Coast in April 2008 – and it is believed some parts of Newcastle in the 2007 floods)

What is the 1 in 100 year flood?

There is no such flood as a “one hundred year flood”, even though this is a commonly used term in everyday language. All floods are different. We do not know when the next flood will occur, or how big it will be. But we can estimate what the likelihood (probability or chances) of a certain size flood are at a given location for a given period of time. So for example, if your area has had a (so called) “1 in 100 year” flood, it is a fallacy to think you will need to wait another 99 years before the next flood arrives. Floods do not happen like that. Some parts of Australia have received a couple of “1 in 100 year floods” in one decade. On average, if you live to be 70 years old and live at the same location at or below the “1 in 100 year” flood level, you have a better than even chance of experiencing a “1 in 100 year” flood in your lifetime.

We should better refer to a flood that has a 1 in 100 chance of being equalled or exceed in any given year, or a flood that has a 1 in 10 chance of being equalled or exceed in any given year, or a flood that has a 1 in 500 chance of being equalled or exceeded in any given year, all at some chosen location – and so on.

Did the June 2007 floods change Council’s flood classification of my property?

In general, a property can have a physical risk of flooding, yet not be classified as ‘flood liable’ by Council’s Flood Policy. This could occur because a Council’s knowledge of potential flood risks needs to be gained by specialist studies using large amounts of data, complex computer calculations and mapping, taking into account past floods as a guide, and because the Council may not have completed these studies. These studies are costly, require Grant assistance, and take time.

Newcastle City Council’s knowledge of the extent of potential flood risks has been growing over many years as data collection and specialist studies have been progressively carried out over its Local Government Area. Council has used this flood information in its assessment and determination of Development Applications. Council’s knowledge of the day about the flood risks (or otherwise) for any property in the Local Government Area have been available to individuals on application to Council for more than the last 15 years.  While the June 2007 flood event confirmed Council’s flood maps of potential flood risks in many areas, it has not been found necessary to change Council’s mapping of potential flood risks as a result of these floods.

In 2004 Council adopted a Flood Policy. This then legally enabled Council to identify properties affected by Council’s Flood Policy. A property is affected by Council’s Flood Policy if it is wholly or partly within Council’s estimate of the PMF (see section “What is the probable maximum flood (PMF)?”).

How will flooding affect the value of my property?

If your property is identified by Council as being in a flood affected area, the real flood risks on your property have not changed, rather, present estimates of the risk as identified by Council are available to assist and inform decision making.

Ultimately, the market determines the value of any property. Individual owners should seek their own valuation advice if they are concerned that the flood risk estimation available from Council may influence their property value.

Can I get house and contents insurance if my house is at risk of flooding?

Until recently flood insurance was generally not available for residential property in Australia. However, some companies now offer flood insurance.

The information used by Insurance companies to offer flood insurance and set premiums in the Newcastle Local Government Area has not been supplied by Newcastle City Council.

In general Insurance policies and conditions (relating to flooding and stormwater) will not be based on the definition of flooding that Newcastle City Council is required to use by the NSW Government for its development of Floodplain Risk Management Plans. Also insurance policies may change over time and may differ between insurance companies. You should confirm the specific details of your current insurance situation about flooding directly with your insurer.

Will I be able to get a home loan if my land is at risk of flooding?

Property owners who are concerned about their ability to obtain a loan should clarify the situation with their own lending authority.

Will clearing creeks prevent flooding?

Clearing creeks to enable more water to flow but will not prevent flooding during major and extreme rain. Like storm water drains, natural creeks can only take so much rain before they overflow regardless of any debris or vegetation.  In natural flood environments, during floods the whole of the floodplain is mobilized and oftentimes more water flows on the floodplain than in the creek or river.  In contrast, removing vegetation from creeks increases erosion from banks which causes significant structural problems within the creek. Vegetation removal also undermines the health of waterways by removing natural filtration which improves water quality downstream. Maintenance of creeks is regulated to control the removal of vegetation or habitats.

What about a local street drainage problem?

Investigations show that drain blockages by leaves and other debris is not the cause of local drainage problems. Most often the water simply cannot get away because the drains further downstream are already full. In most areas where flooding occurred in the June 2007 storms, the downstream drains were overwhelmed by the volume and intensity of the water flow, and would not have had the capacity to convey all the floodwaters on the floodplain even if the downstream drains were not already full.

Street drainage is usually designed to drain water from the road, without affecting private property for a 'one in five year' rain event. That is to say that every now and then, it is normal for street drainage systems to overflow. If the street drainage system is overflowing more regularly, there may be a problem that Council needs to have a look at, you should write to Council to describe the problem and Council will respond to your request. The most common cause of more frequent overflowing is the inappropriate design of driveway crossings on the low side of a road. This is where a driveway is built to allow vehicular access to a garage that is lower than the street and the driveway allows water to flow out of the gutter and into the property. You may need to reconstruct your driveway to address this issue. Council does not contribute to the cost of driveway reconstruction. You need Council approval to construct a driveway in the road reserve.

Council is working on identifying areas where additional pits or pipes may assist without making flooding worse somewhere else. Once identified, Council will prioritise these in its works program.