Carol Stewart, Thomas M. Wilson, Victoria Sword-Daniels, Kristi L. Wallace, Christina R. Magill Affiliated with Risk Frontiers, Macquarie University, Claire J. Horwell, Graham S. Leonard, Peter J. Baxter.
Volcanic ash is generated in explosive volcanic eruptions, dispersed by prevailing winds and may be deposited onto communities hundreds or even thousands of kilometres away. The wide geographic reach of ashfalls makes them the volcanic hazard most likely to affect the greatest numbers of people.
by Andrew Gissing, Katharine Haynes and James O’Brien
Floodwaters arising from the rainfall of Ex-Tropical Cyclone Debbie impacted North, South and Central Lismore from Thursday, March 30, 2017. Hundreds of residential and commercial buildings were flooded; several thousand residents and business operators were evacuated. Central and South Lismore are protected by levees but both of these were overtopped.
The Lismore Rowing Club Gauge measured a flood peak of 11.6 metres AHD, the highest recorded since 1974 (12.2 metres AHD). North Lismore was flooded late on the evening of the 30th of March, whilst South and Central Lismore were flooded in the early morning hours of the 31st of March.
Risk Frontiers visited Lismore on the 3rd of April to undertake unstructured interviews with residents and business operators in order to gain preliminary insights into impacts; responses to warnings; sheltering behaviours; how levees may have influenced risk perceptions; and the initial recovery. Our team was integrated with emergency service Rapid Impact Assessment teams to avoid duplication and burden on those impacted. In total we spoke with 22 residents and 23 business operators. In what follows, we highlight key learnings from these early investigations.
Residential flood damages in the main appear to have been restricted to the ground storey areas of raised dwellings, with peak flood heights reaching just inches below second storey living areas. In many cases it would appear that these ground story spaces were likely occupied at the time of the flood and in some cases rented out. The majority were certainly used for extensive storage. There were a smaller number of lower set dwellings in which flooding impacted main living areas.
Almost every home and business on the floodplain had a large muddy pile of possessions stacked on the roadside awaiting council pick-up (Figure 1). In some areas possessions had floated away and were now scattered across open areas. Common household items damaged were carpets; household appliances — fridges; washing machines; dryers; cupboards and drawers; fabric lounge chairs; tables and chairs; hardware; bedding; doors and outdoor furniture. Some people stacked goods on tables or shelves within the ground storey only for tables to float and shelving to fail. Pets were also lost with one family losing some sixty guinea pigs.
Damage to commercial operations varied widely depending upon the type of business. A large number of businesses had suffered significant losses, such as a Hotel, which estimated its damages at $600,000; a hire-car business in which all vehicles were flooded; a whole foods store that lost most stock; a bakery that had lost its ovens and mixing equipment; and a large clothing retailer that was disposing of all of its stock and fittings. Some reported that they were unable to move large pieces of equipment in time. Most reported that they were uninsured or were hopeful that some losses may be claimed through severe storm coverage.
Most flood-affected businesses were closed at the time of our reconnaissance mission for clean-up and restoration. A small number, however, had recommenced trading, albeit on a reduced scale. In a higher area that hadn’t been flooded, a café operator reported that they had run out of food to serve two days running due to increased customer demand.
One business owner expressed frustration concerning the closed access to the CBD, suggesting that allowing earlier access on presenting identification would help. Concern was also expressed about bow waves, arising from motorists and boats driving through floodwaters, causing further flood damage to homes and businesses.
Significant flood velocities occurred through Browns Creek and the adjacent car park causing substantial erosion in the lower area of the car park, and structural damage to the roller doors of a nearby business. Figure 2 shows two trucks washed from an adjacent business into Browns Creek.
Recent commercial developments, with floor levels set above the 1-in-100 year flood level avoided flooding. These businesses included Hungry Jacks, Woolworths, Aldi, Bunnings and Toyota, who were all able to trade directly after floodwaters subsided. Figure 3 shows the raised floor level of the Aldi Supermarket. The operation of supermarkets in Central Lismore during the initial recovery phase likely helped reduce the scale of emergency relief required.
Given that we saw many dwellings where the floodwaters had come only inches from second storey levels, a flood of 1974 or 1954 proportions would certainly have resulted in significantly higher damages, community panic and displacement. Roche et al. (2013) estimated that the total normalised economic cost of the 1954 floods in 2011 dollars throughout the region would have been of the order of $7.5 billion, although the uncertainty in that figure is high. The 1954 flood affected many more catchments in the Northern Rivers region of NSW and occurred prior to reliable insurance statistics and the recent escalation in property values. 28 lives were lost in that event (Roche et al. 2013).
Community response to warnings
The Bureau of Meteorology and the NSW SES provided warnings and information to the community throughout the event via websites, traditional media, door-knocking and social media. The local Council also utilised flood sirens when levees were over-topped.
As reported in the media the majority of residents interviewed did not evacuate instead opting to shelter in a higher story of their home as floodwaters rose. The reasons for doing so varied and included wanting to save possessions, fear of looting, that they had sheltered previously and to enable clean-up to commence earlier.
Many appeared to have been caught off guard by the scale and speed at which the flood occurred and were not able to save many items. Some told us that earlier warnings of a moderate flood gave them a sense of security, false as it turned out, and which was quickly replaced by panic when flood heights exceeding 11 metres were forecast. Others simply thought the warnings were exaggerated and that the flood heights would be less than predicted given that this had been the case in the past. A few of those interviewed, however, thought that a larger flood than that predicted was likely and had taken action in advance.
Overall, people described flood warnings as “OK”. Suggestions for improvement included providing warnings more regularly, perhaps every two hours and providing regular river height readings. One resident expressed concern that residents may still be confused by a river gauge datum change that occurred some fifteen years ago. Another favoured forecasts provided by locals over those derived from automatic gauges and delivered by officials in Sydney.
Pointing to the success of Lismore City Council efforts to provide such information, most residents knew how to interpret gauge levels in terms of the corresponding flood heights in their homes and businesses. The degree to which this knowledge influenced behaviour requires further exploration.
Although a frightening experience for some, many, who sheltered in place, said that they would do it again. Some prepared by stocking up on food, however, the majority did not as they considered they would only be isolated for a few hours at most. Most were caught off guard when power was lost resulting in an inability to cook and use lighting or hot water. This surprised them as the power had remained on during previous floods and although some did expect the power to fail, the length of outage was a challenge for everybody.
One resident described how his medications needed to be kept in the fridge and he had just bought a three-month supply only days before the flood. Although the supply had been ruined because of the power loss he had just managed to keep a small amount cool enough during the flood to keep him healthy.
Another resident discussed how they had not only stocked up on food but had also bought iceboxes and ice in order to keep their food from spoiling in the event of a power outage.
Another resident with a child who requires lung support to sleep evacuated their lower set home and waded, in the dark, through waist high water to a neighbour’s house. As the power remained off for a couple of days they could not return to their home. Another mother who sheltered with her four children and two other adults discussed how they didn’t know if the tap water had been compromised, and therefore only drank the fluids they had in the home. The family had taken the precaution of filling the bath with water when the flooding began; however, the bath had emptied overnight due to a poorly fitting plug.
Many did not have radios, torches, candles or spare batteries. People talked about the isolation as their phone signals didn’t work, laptops ran out of power and they could not access information. Others enjoyed the camaraderie of neighbours who assisted through the sharing and cooking of food for each other (if they had access to gas), and the passing on of information from neighbour to neighbour.
Specifically those interviewed stated:
We stayed. Not the best idea. We lost power. We couldn’t cook. (North Lismore business owner)
My daughter stayed. She is pretty freaked out. Still hasn’t left the house.” (North Lismore Resident)
Next door neighbour stayed. Said it was interesting, was blacked out, had no hot water. Lucky water didn’t get in the house. (North Lismore Resident)
I had food, water and plenty of warm beer. . . I always intended to stay, stayed in 74 . . . its just life . . . (South Lismore resident)
Decided to shelter but didn’t realise the water would get that high or stay for so long . . . Didn’t realise the power would be off for so long . . . just had enough food (South Lismore resident)
Still lifting when the water came through, so had to stay, but would have stayed anyway . . . Went out and got extra food. House is built for it so would always stay . . . Could stay a week, had batteries for radio, didn’t have a generator but have bought one now (South Lismore resident)
Next time I will evacuate as didn’t like being without power . . . bought extra food but didn’t think about the power going off . . . 1 camp stove and 7 people to feed . . . everything in the fridge went off and I couldn’t cook it . . . if it had lasted another 12 hours we would have been in trouble (South Lismore resident)
Four-year old daughter had an ear ache and we were seeing how bad it got. She had a mild temperature and we were giving her Panadol, we were considering calling the SES to take her to the doctors but only if it had got really bad (South Lismore resident)
We have a gas stove and we even cooked for our next door neighbour . . . we have been in floods too many times to not be prepared . . . bought eskies and ice to make sure were ok with food (South Lismore resident)
Didn’t expect the power to go off for so long, only expected it to go off for an hour or two (South Lismore resident)
Didn’t want to evacuate, we had enough food and lived on sandwiches. We were due to do a shop on Wednesday as we only get paid fortnightly so we just ate what we had . . . could only have lasted another day. We didn’t want to evacuate because of looters, if we lost our contents that would be it . . . I’m on medications that need to be in the fridge and had just picked up a three month supply and they are all spoiled . . . I had just enough to get me through. Such a disappointment that the electricity went out for so long. Because the TV went out we weren’t able to get any information, take that out and we have nothing. Don’t have a radio, have a mobile but it ran out. (South Lismore resident)
Stoked up on food and water but then the power went off and it all went off . . . a bloody waste of time . . . if I’d known the power was going to go off I would have bought a generator in to save the food… we choose to live here and I wouldn’t want to live anywhere else (South Lismore resident)
Didn’t have time to get food and didn’t think it was going to be this bad. Had some food but had to throw it away. Fridge off for a day and a half and it just goes off so quickly (South Lismore resident)
Perception of Flood Levees
Businesses in the CBD thought some may have put too much faith in the Central Lismore levee and got caught out. Some were said not to have packed up to the amazement of other businesses.
Some perceived the Central Lismore Levee as being both a blessing and a curse: it had kept water out previously in 2005 and 2009, however, once overtopped kept water in.
In North Lismore one resident expressed concern that flood behaviour had changed since the CBD levee had been built believing flood levels were now much higher as a result. In other places residents showed us that flood levels were lower than those experienced in 1974.
We observed both formal and informal mechanisms to assist recovery efforts. Emergency services and council staff were assisting with the clean-up, with local volunteer groups such as Rotary provided catering for residents on the street. On an informal level we observed people bringing hot meals for those impacted, and family and friends assisting in the clean-up.
A Facebook Page called Lismore Helping Hands was cited as a fantastic resource, where community members were helping to coordinate the provision of support for others. As at April 7 the page had 6450 members.
Business owners expressed dismay and anger about looting and theft from their clean up piles in the street and were verbally challenging people who were stealing items from shopfronts.
Discussion and conclusions
Though a significant and very damaging event, we were left with a sense that the community was functioning and resilient, getting on with the job of cleaning up.
Much bigger floods are possible in Lismore and there is much to be learned from this event. The physical and social impacts would have been far greater had the floods been only a little higher.
As well as providing more evidence as to the effectiveness of flood mitigation and flood warning systems, the event offers significant opportunities to better understand community risk perceptions, responses to warnings, sheltering behaviours and flood damages.
Several policy and communication issues already apparent include the following:
What should be done to reduce flood damages in enclosed ground floor areas of high set dwellings? These areas should not be rented as habitable space.
Despite evacuation orders being mandatory many residents chose not to leave. This is consistent with other NSW flood events and experience internationally. In larger floods these people could face significant risks. This issue may be difficult to solve: current messages in evacuation warnings mention the possibility of rescue and this in turn implies the availability of rescue resources. This messaging should be reviewed.
The culture of sheltering-in-place during floods requires further in-depth research in order to determine perceptions and beliefs, and, by documenting the experiences in events like this, the risks and challenges. Emergency services must inform people of what they can expect when they shelter-in-place during floods, particularly the likely lack of power and the number of days of isolation. There is a need to ensure people fully understand the possible consequences both physically and emotionally and that it will always be safer to evacuate. The experiences documented to date outline the many risks involved in sheltering and appear to support existing arguments against the adoption of shelter-in-place strategies within green field developments with similar flood risks.
Can levees be raised to reduce the flood risk? Community members are already pushing for increased flood levee protection. However, the original decision to construct the levee to provide protection with a 10% annual chance of over-topping was made based on a study that found larger structural measures were ‘uneconomical, impractical and socially unacceptable’ (Lismore City Council, 2002). In the absence of levee raising or new engineering works, Lismore would be largely reliant on existing non-structural measures including house raising, education, flood warnings and evacuation, and perhaps the voluntary buy back of flood prone properties by the government.
ROCHE K M, MCANENEY K J, CHEN, K AND R.P. CROMPTON, 2011. The Australian Great Flood of 1954: Estimating the cost of a similar event in 2011. Weather Climate and Society DOI: 10.1175/WCAS-D-12-00018.1.
LISMORE CITY COUNCIL 2002. Lismore Floodplain Management Plan. Lismore: Lismore City Council.
Risk Frontiers’ Andrew Gissing joins a panel on RN Radio with Fran Kelly to discuss mitigating disaster and measuring risk in the wake of Cyclone Debbie. Other panel guests include Rob Whelan (CEO, Insurance Council of Australia) and Karl Mallon (Director of Climate Risk).
By Thomas Mortlock, Niyas Madappatt and Matalena Tofa
Severe Tropical Cyclone Debbie made landfall near Airlie Beach on the north Queensland coast at midday on 28th March 2017. It was a slow-moving category 4 system that generated wind gusts exceeding 160 km/hr, heavy rainfall, large waves and storm surge at the coast. 27 hours later, after having tracked inland over the townships of Proserpine and Collinsville, it was downgraded to a Tropical Low. A team from Risk Frontiers travelled to the landfall site and surrounds a day later to assess the damage.
Surface water and river flooding
From the air, the most obvious impact of TC Debbie was floodwater. The slow forward speed of the cyclone (average 9 km/hr) contributed to surface water flooding from large amounts of accumulated rainfall on Tuesday 28th while river levels at the coast peaked a day later as the inland movement of the (then) ex-tropical cyclone released large amounts of rainfall on the hinterland. Speaking to local residents in Mackay, the delayed flooding of the Pioneer River (Figure 2 A) came at a time when most were reeling from the initial passage of the Cat 4 system.
From our observations, most main road and rail lines remained free from floodwater because of the appropriate elevation of both above the surrounding floodplain. The Bruce Highway – the main arterial between Mackay and Proserpine – was temporarily cut at Gunyarra but good gullies and freeboard (visible in Figure 2 B) ensured this was short-lived.
Wind gusts of up to 260 km/hr were recorded at Hamilton Island (50 km due east of Proserpine) and 160 km/hr at Proserpine on 28th March. Further south at Mackay, the maximum gust speed was considerably less (95 km/hr).
Driving north on the Bruce Highway from Mackay the visible signs of wind damage increased. Fallen power lines and trees were common from Seaforth north. Around Proserpine and Hamilton Plains, fields of sugar cane – usually 2 to 3 metres in height – were bent knee-high, demonstrating the severity of near ground-level winds in this area. The importance of local topography was also obvious, with steep relief exhibiting worse impacts than adjacent valleys (Figure 3 A).
With the exception of trees fallen on houses, there were few external signs of wind-induced building damage. The design gust wind speed for typical buildings in this region is 248 km/hr. Most post-1986 buildings around Proserpine, for example, experienced ~75 % of the design ultimate wind speed and faired well (JCU, 2017).
The only area where we witnessed significant structural damage was flying over South Molle Island (Figure 3 B). While this resort was half-abandoned prior to Debbie, it demonstrates what can happen with significantly stronger winds and sub-standard building condition.
Figure 3 A) Contrasting impacts of exposed relief (hill in background, trees stripped) and adjacent valley (foreground, foliage and power lines intact), B) Destruction at South Molle Island.
Storm surge is the rise in the ocean water level associated with strong onshore winds and low atmospheric pressure during a cyclone. The ‘surge’ element is additional to the normal tide. On top of the tide and surge (collectively known as the ‘storm tide’), waves can further contribute to coastal flooding locally by increasing the surface water level (wave setup) and providing momentum for an up-rush of water up the beach (wave runup). At the Mackay wave buoy, for instance, waves reached 8 m around 5 am on the Tuesday morning.
Overall surge impacts were limited because: 1) the strongest winds occurred two hours after the morning high tide and 2) the cyclone made landfall over a section of the coast partially shadowed by the Whitsunday Islands. If Debbie had made landfall two hours earlier, an extra 1 metre of storm tide may have been possible.
As it happened, water levels were able to breach most beaches on Tuesday morning as sheet flow rather than causing any significant inundation. This was largely because of the delayed landfall of Debbie after the highest state of the tide. The largest recorded storm tide was around 4.1 m at Laguna Quays (1.6 m surge), and 2.7 m at Shute Harbour (0.9 m surge). The worst affected areas that we observed in terms of surge and erosion damage were Seaforth, Midge Point, Laguna Quays, Airlie Beach and Shute Harbour.
At Seaforth, the beach was stripped away and waterfront property damaged (Figure 4 A). At Midge Point there was no surge-related damage because property was well set-back from the shoreline and the mangrove swamps dampened inundation velocities and extents. At Laguna Quays, boats were damaged and the storm tide large enough to break concrete-clad pontoons from their moorings and deposit them above the marina on adjacent high ground. At Airlie Beach and Shute Harbour, several boats were washed up onto the beach (Figure 4 B) and sand and saltwater extended onto the promenade.
Figure 4 A) Storm surge damage at Seaforth, B) boats washed up onto Airlie Beach.
Debbie has probably caused more damage after her transition to a Tropical Low than during her time as a Severe Tropical Cyclone. While witnessing the impacts of Debbie first-hand was impressive, the most striking thing we saw was the positive attitude and community spirit of Queenslanders to clean-up and get-by under very stressful circumstances.
Thanks to residents at Seaforth for providing valuable information on surge impacts in the middle of their clean-up operation. Thanks also to the Cyclone Testing Station group at James Cook University for sharing their Severe Wind Hazard Preliminary Assessment, and RegionalAir charter flights from which all aerial photographs were taken.
Risk Frontiers’ Andrew Gissing was invited to be part of the Channel 10 in-studio television broadcast on Severe Tropical Cyclone Debbie. This gave viewers the opportunity to hear expert insights on the management of the disaster as the cyclone approached the Queensland coast.
“Innovators take to the stage with ideas for building community resilience towards flooding and other disasters
By Ika Koeck, IFRC
From floating structures to sustainable health insurance for flood-affected communities, the First Innovation in Flood Resilience Conference, held recently in Jakarta, saw the presentation of innovative ideas and projects to improve disaster management and build community resilience towards flooding.
The two-day conference was a collaboration between the Indonesian Red Cross Society, the International Federation of Red Cross and Red Crescent Societies (IFRC) and Zurich Insurance, to match local grassroots innovators to potential funders and other partners to scale up ideas and solutions in flood management. Other key partners to the conference included Pulse Lab Jakarta, the Humanitarian Leadership Academy and Hamburg University of Technology.
The Indonesian Civil Society has already been developing their own innovative solutions to improve flood response within the country. However, most innovators struggle to gain the recognition and support needed to take their ideas forward.
Giorgio Ferrario, Head of Delegation for the IFRC Country Cluster Support Team in Indonesia and Timor-Leste, said that a joint effort between private sectors, academic institutions and humanitarian organisations is key to addressing community priorities in a sustainable and effective way.
“We are consciously working in new and innovative ways with non-traditional partners, as the challenges we face with recurring disasters continue to grow in unprecedented ways,” said Ferrario.
The highlight of the conference was when the innovators took to the stage during An Ideas Pitch session to narrate their ideas and what motivated them to seek a change in their own communities before a panel of judges.
Nine promising local inventive and original solutions from different organisations including Risk Frontiers, Starside, Mallsampah.com and Garbage Clinical Insurance took part in the competition. The winners of the session, Mallsampah.com and two other innovative ideas from Risk Frontiers and Telaga, will receive grants to keep developing their innovations.
“Since waste management is a major issue in our village, we decided to create a recycling system where people can exchange their waste for medical services,” explained the creators from Garbage Clinical Insurance. “Everyone should have access to health insurance.”
Wirahadi Suryana, the Director of Corporate and Commercial in Zurich Insurance Indonesia said that the company has been working together with the Red Cross since 2013, focusing on building community resilience before, during and after disasters.
In line with the conference, Zurich Insurance also highlighted their mobile application for flood response. “Our team has developed a mobile app called Z-Alert, which can be downloaded for free in the AppStore and Google Play. Users will be able to locate disasters around them, ranging from floods, traffic accidents and even power outages,” said Suryana.”
by Thomas R. Mortlock, Ian D. Goodwin, John K. McAneney and Kevin Roche.
In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern
seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave
heights offshore of Sydney were not exceptional, nearshore wave conditions were such that
beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave
and current behaviour as well as contemporaneous sand transport shows the east to north-east
storm wave direction to be the major determinant of erosion magnitude. This arises because of
reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.
This paper by R. J. Blong, P. Grasso, S. F. Jenkins, C. R. Magill, T. M. Wilson, K. McMullan and J. Kandlbauer was published on 26th January 2017 in the Journal of Applied Volcanology.
Volcanic ash falls are one of the most widespread and frequent volcanic hazards, and are produced by all explosive volcanic eruptions. Ash falls are arguably the most disruptive volcanic hazard because of their ability to affect large areas and to impact a wide range of assets, even at relatively small thicknesses. From an insurance perspective, the most valuable insured assets are buildings. Ash fall vulnerability curves or functions, which relate the magnitude of ash fall to likely damage, are the most developed for buildings, although there have been important recent advances for agriculture and infrastructure. Read more…
It is never safe to drive through floodwaters, no matter the circumstances. Learn from Sonya’s experience in this NSW SES video about why you shouldn’t take your vehicle into floodwaters. The data in the video comes from BNHCRC research with Risk Frontiers.
The following news pieces have been picked up by various sources from a paper published late last year in the Journal of Geophysical Research, Oceans titled “Tropical and extratropical-origin storm wave types and their influence on the East Australian longshore sand transport system under a changing climate” by Ian Goodwin, Thomas Mortlock and Stuart Browning. Thomas Mortlock is a member of the Risk Frontiers’ team and Ian Goodwin and Stuart Browning are members of the Marine Climate Risk Group at Macquarie University. Click here to read entire article.