The benefits of cleaning and clearing are only temporary unless these continue to be maintained. Other structures such as roads, railways and embankments also have an impact on flood risk management because they can alter flood flows and behaviour. Floodgates can also be used to prevent backflow from river systems into drains.
In addition to the zoning and development controls for new and re-developments mentioned above, modifications to existing property are also essential if the growth in future flood damage is to be contained.
Land filling involves building up low-lying areas and can improve the flood immunity of structures constructed on that land, but can adversely affect flood behaviour elsewhere and therefore is generally limited to the fringes of the floodplain.
Flood proofing involves the sealing of entrances, windows, vents, etc. Generally it is only suitable for brick commercial buildings with concrete floors and it can prevent ingress for outside water depths up to approximately one metre. Ideally, new developments would use flood resilient designs and materials, as addressed in Question 8.
House raising is widely used to reduce the frequency of inundation of habitable floors, thereby reducing flood damage.
This approach provides more flexibility in planning, funding and implementation than removal of development. However, its application is limited as it is not suitable for all building types and only becomes economically viable when above-floor inundation occurs frequently for example, on average at least once in every 10 years.
It also does not remove the risk to people who occupy the house, particularly in larger flood events. Figure Property modification measures to manage flood risk in new and existing development areas. There are instances where a large proportion of, or an entire town has been relocated due to flooding.
For example Clermont, Queensland, was relocated to higher ground after the flood of This approach generally involves voluntary purchase and demolition of the residence to remove it from the floodplain. Voluntary purchase has no environmental impacts, although the economic cost and social impacts can be high.
Communities often oppose such schemes due to the impact on their community, surrounding property values and way of life. Measures to modify the response of the community to a flood are essential to deal with residual flood risk, because development controls and flood mitigation works generally cannot deal with all possible floods. There are four main types of flooding experienced in Queensland. River flooding happens when widespread and prolonged rain falls over a river catchment.
Creek flooding happens when intense rain falls over a creek catchment causing the creek levels to rise, which often occurs quickly with limited warning. Overland flow happens as water travels over the land during heavy rainfall events and generally occurs over a short period of time. Storm tide flooding happens when a low pressure system or strong onshore winds force sea levels to rise above normal levels, creating a storm surge that can cause flooding of low-lying areas close to tidal waterways and foreshores.
Hear from our friend Jesse as he shows us how our river catchments work and where flood warnings come from. Depending on your location, you may experience floods differently. Your location will determine whether you are likely to experience river, creek, overland flow, storm tide flooding or a combination of several of these types of flood risks. Understanding the type of flooding you are likely to experience will help you to prepare for how quickly the flooding is likely to occur, the duration of heightened flood water levels, where flooding is likely to occur, and the impact it will have on your home, workplace and transport networks.
Isolation is an issue that can impact people living in elevated areas that are surrounded by water sources. This was due to a number of factors, including cost, the need to wait for insurance decisions, and there being more properties to be rebuilt than there were builders. A number of abandoned properties were evident in the case study area with a local councillor suggesting up to 10 per cent of properties may be abandoned permanently.
The loss of sentimental items was also deeply felt by many respondents. Flood insurance was a source of dissatisfaction for many respondents, with 33 per cent having thought their insurance covered them for all types of flood. While some respondents believed flood should be a standard inclusion on insurance policies, others expressed cynicism and distrust in the insurance industry believing they would not make flood coverage more accessible.
Some considered insurance to be too expensive. Respondents were largely positive about the considerable amount of help from volunteers provided on the first and second weekends after the flood, but there was a feeling that the volunteers, while eager, were not well organised. The volunteers were held in much higher regard than the city council and SES, but many residents reported not having seen either council workers or SES volunteers during the flood or in the immediate clean up.
The one exception to this was a local councillor who was held in high regard by residents for her involvement in the flood response.
Most Brisbane respondents were not considering significant changes to reduce their flood risk. While 50 per cent stated they were likely to or had modified their insurance policy, few other changes were likely to be implemented. While some properties were being raised or rebuilt at a higher level, many respondents did not see the value in this.
Residents largely felt responsibility for flood mitigation was in the hands of the city council, as well as better management of Wivenhoe Dam, and felt there was little they could do personally to reduce their risk.
While cynicism towards insurance and the local council were very common, there was a strong feeling of resilience in the community. Many respondents talked of how much closer they felt to their neighbours and wider community, expressing that, while the flood was a negative experience, it had produced some positive outcomes.
Researchers came across two girls offering free drinks to flood victims and volunteers. The driver of this vehicle had lost the contents of her home in Gympie due to flooding and wanted to help others affected by the floods. In Donald, the perception of risk was low with few residents making adjustments to protect their family and home from flood.
This is not surprising since 55 per cent of respondents indicated that their house was not vulnerable to flood and a further 37 per cent stated they were not aware their home was vulnerable. It is therefore understandable that nearly all respondents indicated nothing had prevented them from making adjustments since they did not believe it was necessary to do so.
The lack of information available to residents prior to and during the flood may also have contributed to their lack of motivation to make changes, such as raising household items, sandbagging the house, devising an evacuation plan, or preparing an evacuation kit.
Residents did not receive detailed hazard information and were therefore uncertain about the risk during this specific event. Known and trusted sources of information e. However, it would be fair to assume that, in light of recent flooding in September , respondents should have had adequate awareness of how they could protect their homes and properties. Nevertheless, the January flood was much larger than that experienced in September , there was a lack of sandbags during the event, the SES was unable to gain access to Donald, and volunteers focused their efforts on specific places instead of working throughout the town where needed.
The cumulative effect of all these issues resulted in many residents being ill prepared. This might explain the fact that a higher proportion of men who completed the survey indicated that they had suffered negative impacts to their wellbeing as a result of the flood as it is predominantly men who physically operate the farm. However, this result contradicts observations by social workers who reported an increase in women suffering from depression.
As with other parts of Australia that were flooded during the —11 summer, the preceding prolonged drought resulted in flood mitigation efforts being placed on the backburner in Donald.
Local government feared criticism from the public if they maintained or implemented flood mitigation works during the year drought and some residents pushed for development in flood-prone areas based on the fact that properties had not flooded since they had lived in Donald.
Many respondents in Donald thought they had full insurance cover but very few actually knew they were covered for all types of flood. The remaining respondents, a little more than half, knew that they were not covered or were covered for storm damage only. Nearly half those who were unaware of their insurance cover indicated they had no previous experience of flood.
Despite many respondents believing in the likelihood of a flood in the next 10 years, many do not intend to make changes to reduce their risk.
Of those who indicated they would consider changes, the most popular methods were to modify insurance policies, improve garden drainage and build permanent barriers around properties, which could prove difficult due to local government restrictions.
Respondents whose wellbeing suffered after the flood perceive that they are less able to make changes to reduce flood risk compared to others in their community. An interesting adaptation that some farmers were making for drought and flood was the planting of River Saltbush as fodder for sheep.
While River Saltbush and Old Man Saltbush grass varieties survive well in high-salinity soils and drought conditions, the River Saltbush survived the flood even though it was submerged for an extended period. In comparison, Old Man Saltbush died off. These findings may prove valuable to other sheep farmers in the area. Although policy changes are hoped to result from such studies, it may take a long time until they are implemented.
Nevertheless, local residents are very positive about the group and the work they are undertaking. The dedication and persistence of this group of residents is not only encouraging to Donald residents, but should serve as a good example to other communities in Australia. Despite the recent flood in , two-thirds of Emerald respondents were unaware that their home was vulnerable to flood.
Evacuation If you need to evacuate, follow the evacuation tips in your emergency plan. If you need to evacuate… Pack warm clothing, essential medications, valuables, personal papers, mobile phone, photos and mementos in waterproof bags to be taken with your emergency kit. If you stay or when you return … Listen to your local radio station for official advice and warnings Don't allow children to play in, or near floodwater Avoid entering floodwater.
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