Related - Floodplain Manager March 2021

East Coast Floods

March saw heavy rainfall from North Queensland to Victoria with flash flooding and major riverine flooding causing mass evacuations, widespread damage and loss of life.

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New South Wales

A low-pressure trough off the east coast and a band of cloud from north of Western Australia merged to cause heavy rainfall and widespread flooding across vast regions of New South Wales (NSW). The east coast of Australia is currently experiencing the end of a La Niña weather pattern, which typically brings more rainfall and tropical cyclones during summer.  Two of Australia’s three wettest years on record have been during La Niña events. Typically, a La Niña sees a 20% increase in average rainfall from December to March in eastern Australia. The NSW and Australian Governments declared 16 natural disaster zones in areas from Tweed Heads to Bega and as far inland as Walgett, covering 63 local government areas. An estimated 18,000 people were evacuated across NSW with 1,400 first responders conducting over 1,000 flood rescues and responding to over 23,000 requests for assistance.

The Bureau of Meteorology (BoM) reported that the highest 24 hour rainfall was 245 mm at Nambucca Heads on the Mid-North Coast (23 March). Rivers across the state reached major flood levels including the Hawkesbury River, Macleay River, Wollombi Brook, Manning River,  Gwydir River,  Clarence River,  and  Colo River.  The Manning River in Taree reached 5.6 m at its peak, falling just short of the record high of 6 m in 1929. In Western Sydney, the Nepean River peaked at 10 m, a level not seen since 1961, but downstream on the Hawkesbury River at Windsor it only reached 13m, 2m shy of the 1961 peak.  The same weather system caused flash flooding in other parts of NSW.

On the Mid-North Coast, many evacuations were ordered throughout the region, including Kempsey, Wingham, Dumaresq Island, Cundletown, Laurieton, Nambucca Heads, North Haven, Dunbogan, Bulahdelah, Kings Point, Macksville and the low-lying areas of Wauchope.  About 2,000 people were ordered to evacuate from the Hawkesbury Nepean floodplains west of Sydney. Evacuation centres were set up across the state as 130 schools were closed and numerous roads were closed by floodwaters.

On 24 March, in Glenorie in north western Sydney, the body of a 25-year-old man was found trapped underwater in a car (more details in following article).

The floods had broad sweeping impacts on animals as skinks, ants, spiders and crickets were seen congregating in large proportions as they scramble to reach higher grounds. Elsewhere, oyster farmers along the coastal estuaries fear that their crops will not survive the prolonged freshwater immersion and they cannot harvest the oysters now because of contamination from the floodwaters.

Clean-up efforts have commenced as the wet weather has eased across much of the state and floodwaters begin to recede. The Australian Government has announced a one-off payment of $1,000 for eligible adults and $400 for eligible children who were seriously injured, displaced, had damage to their homes or who had family members who had lost their lives as a result of the storms and floods. Small businesses are eligible to receive up to $50,000 and primary producers up to $75,000 if they have been affected by floods. The Insurance Council of Australia has announced that more than 11,000 damage claims were made between 20 and 23 March. The worst affected regions were from the Mid-North Coast towns of Port Macquarie, Kempsey, Laurieton and Taree, and western Sydney in localities around Penrith and the Hawkesbury-Nepean Valley. As of 28 March, many residents were advised by NSW SES not to return until they are given all clear by authorities.

NSW Health has issued advice for those in the affected areas during the clean-up stage to treat all floodwater as potentially contaminated. Several beaches on the NSW coast remain closed due to polluted and hazardous water.

Queensland

The same weather event caused flooding across South-East Queensland with residents in the town of Beaudesert, in Queensland’s Scenic Rim, ordered to evacuate as the Logan River reached the major flood level of 12.22 m at Beaudesert. Queensland Fire and Rescue Services (QFES) answered more than 1,130 calls for assistance since Sunday (21 March). SEQ Water said 11 of the state’s dams were spilling over, including the Hinze Dam, which was running at 114% capacity.

Elsewhere, flooding inundated farms and decimated millions of dollars’ worth of crops on properties beside the Dumaresq River which peaked at 8.4 m on Friday 26 March. The Dumaresq River region has been drought-declared since 2014 and experienced its last major flood back in 2011.

At the Gold Coast, a 38-year-old man died after becoming trapped inside his vehicle in Canungra Creek on 24 March 2021.

Victoria

Heavy rains of 150 mm in 24 hours on 24 March,2021 has caused flash flooding in parts of Gippsland, Victoria. About 2,500 residents were without power across eastern Victoria, including most residents in the remote town of Mallacoota. The Victoria State Emergency Service (VICSES) received 149 requests for assistance between 24 and 25 March 2021.

(Read here, here, here, here, here, here, here, here, here, here, here, and here).

Man Drowns After Becoming Trapped Inside Vehicle

A 25-year-old man has died when his vehicle became trapped in floodwaters in Glenorie, NSW.

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According to news reports, the man became trapped in floodwaters on Cattai Ridge Road in Glenorie and had called triple zero for assistance. His mobile reception failed after 40 minutes and when police arrived, they could not find the car or its occupant.  His body was recovered from his vehicle later that afternoon.  It was reported that flood gates had been closed but they had been completely submerged by rising floodwaters.  Apparently, he was driving before dawn and would have come around a bend to be confronted by the floodwaters.  It is also thought that the car’s electrics ceased to operate when the car entered the water, and the man was unable to open his doors or windows. (Read here).

Early Warning System Failure Blamed for Flood Losses 

A brand new $300,000 early warning system for flood and fire emergencies in the Queensland Gemfields did not alert residents of impending floods.

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On 17 March, a localised weather event dumped 215 millimetres into the Retreat Creek catchment in 24 hours.  This flooded low-lying areas in the central Queensland township of Sapphire which were evacuated but some people had to be rescued from rooftops. Residents of the affected suburbs felt that if the sirens were sounded earlier then there would have been more time to evacuate the area.

Central Highlands Mayor Kerry Hayes said in a statement that the decision was made not to activate the system because, “By the time information was received from gauges in the catchment area, the river was already close to peaking” and that an emergency SMS had already been issued to local residents and the emergency services were already on the scene. In response, Council has shifted focus to the synchonisation of traditional warning systems and the newer sirens to allow for better preparation in future floods. (Read here and here).

Climate Change Could Collapse Financial System

The Australian Prudential Regulatory Authority (APRA) has warned that the effects of climate change could lead to rising insurance premiums which may leave many Australians uninsured, and threaten the overall stability of the economy.

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The cost to the insurance industry from extreme weather and natural disasters between November 2019 and February 2020 was approximately $5 billion. As climate change threatens to increase the frequency and extremity of such events in the future, APRA predicts that a shortage of customers and the inability of insurers to pay every claim will create an unstable economy. APRA has recommended that large financial institutions should consider the financial risks and liabilities posed by climate change. (Read more here).

New Flood Warning Funding for Far North Queensland

Regions of North Queensland are set to receive 171 flood warning infrastructure devices in response to the devastating 2019 floods.

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The devices which will include a mixture of flood warning gauges, river gauges, cameras and signage will be delivered in the next 12 months as part of the Flood Warning Infrastructure Network (FWIN), a $8 million project funded through a disaster recovery package. The devices will be distributed between North-west Queensland, Far North Queensland and the Townsville region and will provide information to councils from across the region to assist with planning when the heavy rainfall occurs. (Read more here).

Determining the Cause of Underinsurance in Australia

A new national study has found that underinsurance is commonly a product of a lack of knowledge of options and a lack of trust in insurers, and more insurance is not necessarily the solution.

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Up to 10% of homeowners do not have home insurance, and about 40% of renters do not have contents insurance. This makes post-disaster recovery much more expensive and difficult. Key causes for this are a lack of clarity on what insurance covers or does not cover, and a lack of trust in insurers based on unfavourable previous experience. Making insurance work better for the public by making it more equitable and accessible is advised as a better solution compared to simply encouraging renters and homeowners to purchase more insurance. Based on an understanding of why people are underinsured or uninsured, this research suggests that governments should not rely on individuals to manage their own risk with insurance, and that the government has a responsibility to protect its citizens with tools that include but also go beyond insurance. (Read more here).

Why Flooding Disadvantages the Disadvantaged

The University Centre for Rural Health in Lismore, using data following Cyclone Debbie in 2017, found that 80% of people in Lismore’s flood-affected areas were living in the lowest socio-economic neighbourhoods.

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The study also found that participants living in the lowest socio-economic neighbourhoods had significantly higher rates of smoking and alcohol consumption and were also more likely to have pre-existing mental health conditions such as depression and anxiety. Furthermore, up to 10% of homeowners or mortgagees are without home insurance and about 40% of renters are without contents insurance.  This occurs in high flood risk areas because insurance premiums are often unaffordable. The study showed that the stress of flooding itself, plus financial stress including the inability to insure a property, exacerbates pre-existing health, substance dependence and violence issues among the socially vulnerable.  These findings have also been found in overseas research. Redlined neighbourhoods in the USA are predominantly non-white and were historically delineated as undesirable for mortgage lending due to high concentrations of racial minorities with typically lower socio-economic status. Today, although redlining is no longer practiced, in 38 major metros in the USA, more than $107 billion worth of homes at high risk for flooding were located in historically redlined neighbourhoods. (Read more here and here).

Extended Closing Date for FMA Excellence Awards

Floodplain Management Australia (FMA) has announced that the closing date for the national awards has been extended until 6 April , 2021.

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The FMA Excellence Awards showcase the work professionals in the field of flood risk management have undertaken in the past 24 months and comprises three categories: NRMA Insurance Flood Risk Management Project of the Year, Allan Ezzy Flood Risk Manager of the Year Award, and Young Floodplain Manager of the Year Award. The winners of the 2021 Excellence Awards will be announced at the FMA Online National Conference to be held on  27 May 2021. (Read more here).

Cascading Risks Associated with Glacier Bursts

Glacial Lake Outburst Floods (GLOFs) pose a serious threat to mountainous communities and cause cascading risks such as landslides, avalanches, and flash floods.

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A study has used 40 years of satellite observations across India, China, Nepal and Bhutan, to reveal that glaciers have lost the equivalent of over 45 cm of the ice each year since 2000. This trend is set to worsen under climate change, which would lead to communities with multi hazard risk hotspots such as ecological fragility, active seismicity, high infrastructure exposure and socioeconomic vulnerabilities to become increasingly and more severely affected. To manage cascading risks associated with GLOFs, the Sendai Framework proposes four strategic actions: understanding risks in hotspots, strengthening risk governance in fragile terrain, building resilient infrastructure, and enhancing preparedness. (Read more here).

Atmospheric Rivers Flood New Zealand

An article published in Environmental Research Letters has found that 90% of floods in New Zealand between 2007 and 2017 occurred during Atmospheric River Events.

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Atmospheric rivers (ARs) are narrow and elongated regions of enhanced horizontal water vapour transport. Researchers in this article developed an AR identification method and analysed daily station data across 11 of New Zealand’s weather stations to test for the concurrence of ARs and extreme rainfall. The results indicated that at least 70% of the top ten most extreme rainfall days between 1980 and 2018 were associated with AR conditions, and 90% of floods in New Zealand between 2007 and 2017 occurred during an AR event. (Read more here).

Role of Neighbourhood‐Level Considerations in Community Flood Resilience Planning

A paper published in the Journal of Flood Risk Management has revealed that resilience is influenced by the socioeconomic attributes of a community regardless of flood risk.

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The researchers undertook a comparative study of three different locations in the City of Hampton, Virginia. While they each were presented with common coastal flood challenges, their neighbourhood‐level resilience differed as a result of socioeconomic attributes. The study compared resilience investment options preferred by the communities including protection, accommodation, and relocation. The results showed that each case study location had its own unique contextual circumstances that defined its preferences for different resilience strategies. (Read more here).

Politics of Flooding

A recent study published in the Journal of Environmental Hazards has shown that floods can become political events which are shaped by political context and tensions.

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The study used a mixed-method approach comparing two similar floods (2005 and 2015) in the north of the UK and related newspaper articles at the time. The researchers undertook a content analysis to investigate how the disaster management by national, regional, and local governments was framed in news media outlets. The study also included a political claims analysis to explore the relationship between actors and how they framed and politicised the disasters through political claims, defined as demands, criticism, and proposals. The results showed that in the case of the 2015 floods, the event was framed in a manner that was heavily affected by the external political context at the time. For instance, the government was criticised and labelled a failure based on the unrelated but politically intertwined tension of lack of disaster relief spending and European Union policies at the time. (Read more here).

Expert-Based Versus Data-Driven Flood Damage Models

Researchers have undertaken a comparative evaluation of expert-based versus data-driven flood damage models for data-scarce areas.

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The case studies included two floods in 2017 and 2019 in two separate locations in Nigeria, Africa. Flood damage data was collected through interviews following the floods to evaluate the performance of the two damage models. The study compared the accuracy of an expert-based approach which combines the vulnerability indicator method and regional expert knowledge, to the data driven approach which uses multivariate empirical flood damage data. The results showed that there was a predictive accuracy of 30% and 38% for the expert-based and data-driven approaches, respectively. The implications of the study show that the inclusion of local experts allows data base models to be tailored specifically to regional situations particularly when data is scarce (Read more here).

Improved Precision Method for Identifying Flood Risk in European Road Network

Researchers have presented an object-based continental-scale assessment of direct flood risk to European road networks using exposure data from OpenStreetMap to compute realistic damage estimates specific to road segments.

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The expected annual direct damage from large river floods to road infrastructure in Europe is $354 million (AUD) per year. In this study, the researchers show that object-based damage models, where the damage accounting takes place at the level of objects (in this case road segments), rather than grid cells, provide much higher resolution and precise outcomes when compared to traditional grid-based approaches. The implications of this study are that targeted risk reduction strategies can be used at identified hotspots in the road network based on segment-specific attributes and damage risk. (Read more here).

Perceptions of Participation in Flood Risk Awareness

An article published in the International Journal of Disaster Risk Reduction has shown that participation is often determined by specific country context but can even differ within countries.

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The researchers undertook 27 expert interviews in Belgium, Germany, Indonesia, Iran, Nepal, Pakistan and Peru between March and August 2020. The participants comprised experts and authorities responsible for initiating and carrying out flood risk management planning in distinct catchments in the seven countries. The participants completed a standard questionnaire which included understanding of term participation, methods used to establish participation specific to country and catchment, the perceived success in such methods and willingness of community participation. It was found that differences of willingness to participate exist within the same country contexts and are, for example, tied to cultural backgrounds of people in rural versus urban settings. Furthermore, willingness to participate was attributed to lack of awareness, but in other contexts, it was due to realisation of responsibility or upon expecting to receive something in return. (Read more here).

Global Changes in Size, Frequency, and Probability of Extreme River Floods

A study has used a global non-stationary approach to examine recent changes in the size, frequency, and probability of extreme river floods using historical river records.

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The researchers’ model observed annual maximum daily streamflow to denoted changes in flood magnitude, return period as assessed in 1970, and corresponding flood probabilities for 10,093 river gauge records from a combination of global and national streamflow archives. The results showed that since the 1970s, the 20‐year and 50‐year extreme river floods have mostly increased in temperate zones but decreased in arid, tropical, polar, and cold zones. In contrast, the 100‐year floods have decreased in arid and temperate zones and show mixed results in cold zones. The study has shown the importance of regularly updating flood hazard assessments under non-stationarity. (Read more here).

International Floods

There were 16 international floods reported across 14 countries in March 2021. At least 45 people died, more than 5,000 were displaced.

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Internationally significant floods included:

Algeria

At least 10 people have died as result of flash flooding triggered by heavy rainfall in the Chlef Province of Algeria. Three cars were swept away, several homes were damaged and large areas of the Oud Sly Commune became inundated. (Read here)

Columbia

Hundreds of municipalities in Columbia have experienced a total of 289 severe weather events, including 146 landslides, 45 floods and 32 flash floods in the period of 1 to 12 March 2021. At least 15 people have died in the Nariño, Huila, Cauca, Cundinamarca, Antioquia and Valle del Cauca departments. (Read here)

Diary

Flood and Coast 2020 Conference and Exhibition
Where: Online and Telford International Centre, UK
When: Multiple online and in person between December 2020 to June 2021
For more information visit here

Call for Papers: Climate Change and Flood Risk Management
Where: Here
When: 20 April 2021

International Conference on Urban Flood Control and River Flood Management
Where: Singapore
When: 03 to 04 May 2021
For more information visit here

Association of State Floodplain Managers 45th Annual National Conference
Where: Raleigh Convention Center, North Carolina
When: 9 to 12 May 2021
For more information visit here

Floodplain Management Australia National Conference 2021
Where: Virtual conference
When: 25 to 28 May 2021
For more information visit here

FLOODrisk 2020 European Conference on Flood Risk Management
Where: Budapest, Hungary
When: 21 to 25 June 2021
For more information visit here

46th Annual Natural Hazards Research and Applications Workshop
Where: Natural Hazards Center at the University of Colorado Boulder
When: 11- 14 July 2021
For more information visit here

Eighth International Conference on Flood Management
Where: The University of Iowa, USA
When: 9 to 11 August 2021
For more information visit here

Australian Disaster Resilience Conference 2021
Where: International Convention Centre, Sydney, NSW
When: 18 to 19 August 2021
For more information visit here

Flood Expo
Where: Birmingham, UK
When: 22 to 23 September 2021
For more information visit here

 

Resources

Cyclone and Storm Tide Resilient Building Guidance for Queensland Homes

The Queensland Government has released Cyclone and Storm Tide Resilient Building Guidelines for Queensland homes located within 50 kilometres of the coastline north of Bundaberg, and Queensland homes located within 100 to 200 metres of an open shoreline respectively. The guidelines provide information on the impacts of cyclones and storm tides on homes, wind classifications for cyclone prone areas, resilient design and construction tips for new and existing homes in cyclone prone areas, cyclone and storm tide resilient building products and systems, and tips for repairing or rebuilding cyclone damaged homes. Click here

Flood Mitigation in the Hawkesbury-Nepean Valley

In 1995, the NSW Government commissioned a documentary on flooding in the Hawkesbury-Nepean valley. This archival documentary was produced to educate public officials and new residents on the Hawkesbury-Nepean valley and the devastating effects of floods and their probability of occurrence. Read here

Capacity of On-Farm Storages Increased by 142% Between 1994 and 2020

A recent report has found the capacity of on-farm storages in the NSW Northern Basin increased by 2.4 times between 1994 and 2020, moving from 574 GL in 1993/94, to 1,395 GL in 2020. The report indicates a strong correlation between the capacity of on-farm storages and the amount of floodplain harvesting undertaken. However, Northern Basin irrigators argue that floodplain harvesting does not equate to on-farm capacity because the uses of each are vastly different. Similar reports on the Macquarie, Barwon-Darling and Namoi rivers will be released in the coming months. Read here

Methodological Framework for Determining an Optimal Coastal Protection Strategy

An article published in Natural Hazards has proposed a framework for a methodology that combines multiple computational models, stakeholder interviews, and optimisation to protect critical coastal infrastructure such as transportation, electrical grid, and emergency services. Read here.

Tool to Assess the Performance of Event‐Based Design Flood Estimation Methods

A paper published in the Journal of Flood Risk Management has proposed a Design Flood Estimation Tool (DFET) which uses a ranking‐based selection procedure to increase accuracy and mitigate uncertainty in calculation routines for 48 ungauged and gauged locations in South Africa. Read here.

Home Flood Resilience Tools – VR Tour

The Ox-Cam Pathfinder Project has created a virtual reality home with interactive features to demonstrate possible flood resilient modifications that can be implemented in the home and information on their protection capabilities. Read here.

Framework for Effective Early Warning Systems

The international development organisation Practical Action has proposed a holistic people-centred framework for developing effective early warning systems (EWS) which involves the local community, considers multiple natural hazards, and considers gender and cultural diversity and perspectives. To produce an effective EWS Practical Action acknowledges that understanding risk, undertaking monitoring and warning studies, effective and tailored communication, understanding response capacity are key.   Read here.

Animated Flood and Rainfall Graphs for NSW:1973-2021

An article published in The Guardian has presented a series of animated graphs showing the daily maximum river height for 2021 overlain with heights from previous years for Port Macquarie, Penrith, Wingham, Richmond and Kempsey. Read here.

Cross-Scale Mismatches Hinder Flood Risk Management       

The author of this article conducted a combination of qualitative and quantitative analysis in Rovaniemi, Finland to show temporal changes and cross-scale interaction in flood risk management. The results showed that cross-scale mismatch such as conflict related to flood defence measures, had led to mistrust by residents in local authorities leading to lessened to preparedness. Read here.