Thirty Rescued as Flash Flooding Hits NSW Coast
Severe thunderstorms caused flash flooding and landslides along the NSW coast from 8 to 9 February. An inland trough travelling eastwards across the state brought intense rainfall to areas between the Shoalhaven and the Hunter regions. Greenwell Point in the Shoalhaven region recorded 368 mm of rain in 24 hours, with 177 mm falling in just one hour. This was larger than a 0.05% AEP rainfall event. At Bellambi, to the north, 96 mm fell in one hour, between a 0.5% AEP and 1% AEP rainfall event.
Flash flooding impacted school grounds in the Illawarra region, triggering evacuation of 3 high schools. Rockfalls and flooding caused the closure of several roads, including the Princes Highway and Seacliff Bridge, and disrupted South Coast train services. Power services to 7,000 people were also disrupted on the Central Coast. The NSW SES performed over 30 flood rescues, a number of which involved cars that had been driven into floodwaters. At Stanwell Park, flash flooding carried a car from a driveway into the sea, where it washed up on the rocks.
Hundreds Evacuated by Air as the Victoria River Floods in the Northern Territory
Six hundred people were evacuated by air from the Victoria Daly Region in the Northern Territory in early March after heavy rainfall caused riverine flooding. Persistent rainfall caused major flooding of the Victoria River and moderate flooding of the Daly River, with the Victoria River peaking at Kalkarindji on 1 March with a flood level of 16.99 m. Flooding inundated several remote communities, leading the emergency services to issue evacuation orders for people in Kalkarindki, Daguragu and Pigeon Hole. Evacuees were airlifted to Katherine, with 290 staying in temporary accommodation at Howard Springs.
La Niña is Weakening
The Bureau of Meteorology (BoM) has indicated that La Niña is weakening and is likely to come to an end. The BoM’s latest Climate Driver Update (issued 28 February) suggests that ocean indicators for the El Niño Southern Oscillation are at neutral levels, while atmospheric indicators remain at La Niña levels. The recent weakening of La Niña led to lower summer rainfall in eastern and central Australia than has been experienced over the past couple of summers. Most climate models that the BoM utilise indicate that tropical Pacific sea surface temperatures will remain neutral through to May, while one suggests the El Niño threshold will be reached in May. However, ENSO forecasts for this time of year are understood to have lower accuracy than for other seasons.
Insurance Loss of $840 Million from October Flooding
PERILS has estimated that the October floods in southeast Australia resulted in an insurance loss of $840 million. Heavy rainfall in October led to flooding in the Murray-Darling Basin in NSW, Victoria and South Australia with flooding largely impacting inland rural areas. The floodwaters damaged homes, infrastructure, businesses and agriculture. The estimated $840 million insurance loss is significantly smaller than the $6,292 million loss from the February-March 2022 flooding in eastern Australia. This is because the October floods largely impacted inland rural areas while the February-March floods impacted coastal regions with larger populations.
(Read here)
Queensland Buyback Scheme Underway
Following the February 2022 floods, homes in south-eastern Queensland are being accepted into the state’s Voluntary Home Buyback Program. The $350 million program is part of the Resilient Homes Fund administered by the Queensland Reconstruction Authority and is expected to buy 500 homes in high flood risk areas. The program is voluntary, with houses accepted into the scheme sold to the local Council, demolished and the land rezoned as “non-habitable”. Buybacks are underway, with over 40 homes already accepted in Ipswich. However, over 5,000 homeowners have registered for the Resilient Homes Fund, far in excess of the capacity of the program.
(Read here)
Flooding Triggers Bird Breeding Event in Western NSW
Flooding in western NSW over the past few months has provided the opportunity for a widespread bird breeding event. Rivers in the Murray-Darling Basin experienced prolonged major flooding last year, filling and rejuvenating wetlands. A proliferation of invertebrates, plants, frogs and fish in these ecosystems has produced ideal breeding conditions for many waterbird species, including pelicans, swans, ibis and royal spoon bills. The mass breeding event has presented an opportunity for bird populations to rebound after years of drought and reduced breeding opportunities.
(Read here)
Draft DPE Shelter-in-Place Guideline
The NSW Department of Planning and Environment (DPE) placed a draft Shelter-in-Place Guideline on public exhibition. The DPE has indicated that evacuation is the preferred emergency response strategy for flooding, but acknowledge that there are circumstances in which evacuation is not always possible. The draft guideline is not intended to be legislated and provides guidance on the contexts in which shelter-in-place could be an appropriate alternative to evacuation out of the floodplain. The guideline suggests that this could include situations such as flash flooding where flood warning time and flood duration are less than 6 hours. The exhibition period for the draft guideline finished on 28 February. A panel discussion on the topic was held in February at the quarterly meeting of the NSW/ACT Chapter of Floodplain Management Australia (FMA).
(Read here)
CSIRO Shortlists Projects for Northern Rivers Flood Resilience
In late February $50 million worth of projects intended to improve flood resilience in the Northern Rivers region were announced. Last year $150 million of federal funding was allocated to flood mitigation projects in the region and the CSIRO was tasked with engaging with local governments, state agencies and the community to shortlist potential projects. The CSIRO has shortlisted 62 projects from 300 submissions. On 23 February the first round of projects, totalling $50 million, was announced. The projects include upgrades to pumps and pump stations in Lismore, a new pump system in East Murwillumbah and the installation of box culverts in Grafton. Regional community flood risk awareness will also receive $3 million. The projects will be delivered by the NSW Reconstruction Authority and the Northern Rivers Reconstruction Corporation.
(Read here, here, here and here)
BoM Weather App Updated Push Notifications
The Bureau of Meteorology (BoM) has updated its BoM Weather App to change the functioning of push notifications. Previously users would receive push notifications for flood hazards within a 10 km radius of their set location. However, in densely populated urban areas flood hazards 10 km away often are not relevant to the set location. Therefore, the BoM has updated the app to send push notifications for flood hazards within a 5 km radius only.
New Hazards Near Me App in NSW
The Fires Near Me app has been updated to include flood information and has been renamed to Hazards Near Me. Traditionally used to visually convey information related to local bushfire emergencies, the NSW Rural Fire Service’s Fires Near Me app was updated by the NSW Government in February 2023 to include information on local flood emergencies. The app has been rebranded as Hazards Near Me and further alert types are intended to be added to the app over time.
(Read here)
Nominations Open for FMA Excellence Awards
Nominations for the 2023 FMA Excellence Awards have now opened and will close on Friday 24 March. The awards recognise contributions of individuals and organisations towards the promotion of wise land use planning, flood impact reduction, flood emergency management or community flood recovery. The 3 categories of Excellence Awards are the FMA-IAG Flood Risk Management Project of the Year, the FMA-Allan Ezzy Flood Risk Manager of the Year and the FMA-IAG Young Floodplain Manager of the Year Award. The winners of the 3 categories will be announced at the FMA National Conference, which is being held between 23 and 26 May at Luna Park in Sydney.
(Read here)
First Meeting of Hazards Insurance Partnership
The new Hazards Insurance Partnership (HIP) held its first meeting in early February in Brisbane. The meeting was attended by the federal Emergency Management Minister Murray Watt, the Co-ordinator General of the National Emergency Management Agency (NEMA) and representatives of the Insurance Council of Australia and insurance companies. The partnership aims to improve targeting of investment in disaster mitigation, including flood mitigation, and to address concerns related to premium affordability. The partnership aims to facilitate the sharing of information regarding disaster risk to better inform decision-making regarding investment in disaster-mitigation projects.
Auckland’s Wettest Month on Record
January 2023 was Auckland’s wettest month since records began in 1853. New Zealand’s National Institute of Water and Atmospheric Research (NIWA) has indicated that 539 mm of rain fell on Central Auckland during January, which was 119 mm more than the previous record of 420 mm set in February 1869. On 27 January alone, 280 mm of rainfall was recorded at Albert Park, with 211 mm falling within a 6 hour period. The intense rainfall on 27 January was the product of a complex combination of climatological factors, including the persistence of La Niña warming the western Pacific. A marine heatwave increased the available moisture in the atmosphere, which was transported towards Auckland by an atmospheric river and blocked by a high pressure area to the south. The resultant intense downpour that drenched Auckland produced widespread flooding with an Annual Exceedance Probability of 0.5%. The flooding destroyed dozens of properties, inundated Auckland International Airport and resulted in the loss of life of 4 people.
Auckland’s Stormwater Drainage Unprepared for Climate Future
Recent flooding in New Zealand has highlighted the limitations of Auckland’s existing drainage systems for dealing with climate change. The Auckland floods in late January 2023 were closely followed by widespread flooding across New Zealand’s North Island when Cyclone Gabrielle hit the island from 12 February. New Zealand’s National Institute of Water and Atmospheric Research (NIWA) has pointed to climate change as a potential contributor to the intensity of both rainfall events, emphasising that one degree of warming can increase the air’s capacity to hold water vapour by 7% and make rain bursts 10-20% heavier. The recent floods have highlighted that Auckland’s existing stormwater drainage systems, which were designed for climatic conditions 50 years ago, are no longer fit for purpose. Further, extensive urbanisation over recent decades has led to more impermeable surfaces, increasing rapid run-off during rainfall. With rainfall intensity predicted to increase further due to climate change, researchers have suggested the exploration of nature-based solutions in Auckland for flood protection.
Centralised Power Systems Vulnerable to Extreme Weather
Centralised power systems are vulnerable to severe weather events, which are increasing in intensity due to climate change. During Cyclone Gabrielle, New Zealand’s national power grid operator Transpower declared a grid emergency. Several regions lost power due to intense rainfall and flooding. Centralised power systems are susceptible to single points of failure, which means that they are vulnerable to severe weather events, as experienced by New Zealand’s North Island. Researchers from Victoria University of Wellington are exploring the potential role that microgrids and peer to peer (P2P) energy systems could play in increasing the resilience of energy systems to extreme weather by decentralising power supply.
Syrian Homes Inundated by Dam Damaged by Earthquake
The Syrian town of Al-Tloul was flooded when a dam collapsed after being damaged by the Turkey-Syria earthquakes. On 6 February a magnitude 7.8 earthquake struck Turkey and Syria, followed by a series of aftershocks and then a second earthquake of magnitude 7.5. These earthquakes killed more than 50,000 people across Turkey and Syria, including 35-40 people in the town of Al-Tloul near the Syria-Turkey border. Cracks in an agricultural dam along the Orontes River upstream of the town began to appear in the days following the earthquakes, which locals attempted to fortify using sandbags. Approximately 500 households were evacuated from the village on 8 February before the dam was breached on 9 February. The dam breach, in combination with high river flows from recent heavy rain, flooded around 1,000 homes in Al-Tloul and neighbouring villages and inundated thousands of acres of wheat crops.
(Read here, here, here and here)
Sea Level Rise Impacts to Hit Sooner than Expected
Revision of global elevation models suggest that many low-lying areas could be inundated by sea level rise sooner than expected. Most current models of sea level rise use radar-based data to represent land elevation. However, radar is not able to penetrate vegetation. Therefore, radar-based data can overestimate surface elevations. A new study from the Netherlands is using satellite LiDAR elevation data to more accurately identify low coastal areas at risk of inundation within the first 2 m of sea level rise. The study has found that the inundated area in the first 1 to 2 m of sea level rise could be double previous estimates.
Future Coastal Flooding to Disproportionately Impact Developing Nations
Episodic coastal flooding caused by climate change will have more severe socioeconomic impacts on developing nations than developed countries. A recent study, published in Frontiers in Marine Science, by researchers from the University of Melbourne, focussed on the distribution of impacts of future extreme coastal flooding. The study found that the annual damage costs for developing nations will be more than 5% of their national Gross Domestic Product (GDP) if adaptation measures for coastal defence are not implemented. This is compared with developed countries, which are more likely to have the capacity to undertake these adaptation measures, where the annual damage costs would be less than 3% of national GDP. The study identifies Asia, West Africa and Egypt as the areas for which future extreme coastal flooding will bring the most severe costs.
Exposure to Glacial Lake Outburst Floods
Over 50% of people exposed to glacial lake outburst floods live in India, Pakistan, Peru and China. Glacial lakes are often formed by unconsolidated mounds of glacial moraine left behind during glacier retreat. The number of glacial lakes across the globe has increased by 53% since 1990. A study published in Nature Communications quantifies the exposure and vulnerability to glacial lake outburst floods at a global scale. The study found that the most exposed populations live in the High Mountains of Asia, where around 1 million people live within 10 km of a glacial lake. Populations in the Andes Mountains also have high exposure to glacial lake outburst floods.
(Read here)
International Floods
There were 27 international floods reported across 19 countries in February 2023. At least 114 people died and nearly 75,000 were displaced.
Internationally significant floods included:
Mozambique
Heavy rainfall in the Maputo Province of Mozambique and upstream in South Africa and Eswatini resulted in flooding of the Maputo, Umbelizi and Incomati Rivers between 8 and 12 February. Six people lost their lives in the Maputo Province and emergency accommodation centres housed almost 14,000 people. Flooding damaged thousands of homes, several schools and a number of health centres.
Philippines
Between 13 and 21 February a low-pressure area brought intense rainfall to 8 regions in the Philippines, resulting in widespread flooding and landslides. Over 32,000 people were displaced by the event, 2 people died in floodwaters and almost 140 homes were damaged or destroyed.
(Read here)
Brazil
On 19 February the state of Sao Paulo in Brazil was hit by a deluge, with 682 mm of rain falling in Bertioga within 24 hours. This was 152 mm greater than the previous record of rainfall within a 24-hour period in Brazil. The rainfall produced flooding and landslides along the state’s north coast, killing 40 people and displacing almost 2,500 people. Roads throughout the region were washed out or blocked, leaving communities isolated. Drinking water supply was also interrupted in São Sebastião, Caraguatatuba and Ilhabela due to infrastructure damage.
Peru
Heavy rainfall in early February resulted in flooding and mudslides in the Arequipa and Lima Departments in Peru. Flooding of the Ocoña River in Mariano Nicolas Valcarcel District peaked on 6 February, with many other streams in the district’s steep slopes also breaking their banks. Fifteen people died and almost 250 homes were damaged, as were a health centre and sections of road.
(Read here)
Diary
2023 Natural Hazards Research Forum
Where: RMIT University, Melbourne
When: 1 to 3 May 2023
For more information visit here
2023 ASFPM Conference
Where: Raleigh, North Carolina
When: 7 to 11 May 2023
For more information visit here
Floodplain Management Australia National Conference 2023
Where: Luna Park, Sydney NSW
When: 23 to 26 May 2023
For more information visit here
2023 Lessons Management Forum (AFAC and AIDR)
Where: Canberra, ACT
When: 27 to 28 June 2023
For more information visit here
Natural Hazards Workshop
Where: Natural Hazards Centre. Boulder, Colorado
When: 9 to 12 July 2023
For more information visit here
AFAC23 Conference and Exhibition
Where: Brisbane, QLD
When: 22 to 25 August 2023
For more information visit here
Flood Resilience Study Tour of the Netherlands
Where: Netherlands
When: 28 October to 10 November 2023
Queensland Flood Community of Practice Convenor Piet Filet is inviting Expressions of Interest from anyone in joining a Flood Resilience and Climate Adaptation Study Tour to the Netherlands from 28 October to 10 November 2023.
For more information contact Piet (p.filet@griffith.edu.au).
Joint Coast to Coast and NSW Coastal Conference 2023
Where: Newcastle, NSW
When: 30 October to 3 November 2023
For more information visit here
Resources
Recovery Exercising Toolkit
The Australian Institute for Disaster Resilience (AIDR) has released a Recovery Exercising Toolkit. The Toolkit provides evidence-based guidance and resources focused on recovery from disasters, exploring both early recovery and long-term recovery issues.
(Read here)
Stories of 2022 Flood Recovery
The National Emergency Management Agency has released a short video in which community members share their stories of flood recovery. The video briefly explores the recovery process for Northern Rivers and South East Queensland communities impacted by the 2022 floods.
(Read here)
Lithological Controls on Flooding in the Scamander Catchment
Recent research from the University of Tasmania examined the influence of bedrock lithology on river planforms and channel gradients. The study shows that the steeply incised channels of the Avenue River, with low roughness, confine large floods, resulting in high flows and stream powers. The Scamander River’s rough, shallow channels, on the other hand, have irregular channel form and allow floodwaters to overflow at low levels, resulting in low stream powers.
(Read here)
Google Earth Engine Used for Flood Monitoring
A new study by a group of researchers from the University of Alabama details a new method of using Google Earth Engine’s cloud computing capabilities to process multispectral optical imagery and SAR data to map flood extents. The approach aims to produce flood extent maps in near real-time to inform the decisions of emergency management personnel during floods.
(Read here)
Refining Regional Sea Level Budgets
A new method for investigating sea level budget at sub-basin scales has been developed by a team of researchers from the Netherlands, Germany and Spain. The method uses a neural network approach and a network detection approach to show how variability in sea level is connected between different regions.
(Read here)
Quantifying the Flood Reduction Value of Forests
A report prepared for Britain’s Forestry Commission has updated the quantification of the natural capital value of forests and woodlands for reducing flood risk. The investigation considers the flood water storage provided by these land cover types and calculates the “replacement” cost of providing this flood water storage should the forest or woodland be replaced by grassland or bare soil.
Open-Source Dataset for Hydrology
An international team of researchers has released a new dataset and open-source software called Caravan for hydrological datasets. The dataset standardises existing large-sample hydrology datasets, which include meteorological forcing, streamflow, geophysical, sociological and climatological data for thousands of catchments across the globe.
(Read here)
