Related - Floodplain Manager December 2018 / January 2019

Flash Floods Trap Cars

On 14 and 15 December a low-pressure system caused a heavy downpour in Melbourne and in towns to the north-east which left a hundred vehicles stranded in floodwaters on Hume Highway.

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Melbourne’s inner-city was also badly affected with 30 mm rain falling in 15 minutes. The downpour caused many roads to become inundated and inaccessible. Cars and public transport were stopped in their tracks as the downpour converted Melbourne’s roads and transport infrastructure into floodways.  The deluge also affected several surrounding towns. In a single day, Everton received 165 mm, Carboor Upper 125 mm and Eldorado 110 mm (Read here and here).

Man Dies After Record Rain From Owen

Extreme rainfall caused by Ex-Tropical Cyclone Owen caused severe flash flooding in north Queensland which resulted in the death of an 18-year-old man. 

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According to the Bureau of Meteorology, Owen triggered new daily rainfall records between 15 and 16 December in Far North Queensland with 681 mm of rain recorded in Halifax and 552 mm in Cardwell Range. There were a total of four locations where rainfall exceeded 500 mm in a period of 24 hours. The Townsville local was swimming at a popular picnic area in Big Crystal Creek 75 km north of Townsville when he was swept away by floodwaters (Read here, here, here and here).

Daintree Flooding

Far-North Queensland has seen more flooding this summer as a result of heavy rain.

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Up to 500 mm of rain was recorded within 24 hours in some areas. The Daintree River reached its highest flood level since 1901, peaking at 12.6 metres. The Douglas Shire towns of Daintree and Port Douglas were among the worst hit with hundreds of people cut off by the floodwaters and the surrounding areas were inundated (Read here, here, here, here and here).

Early Warning Network Data Breach

Australia’s Emergency Warning Network (EWN) was recently hacked, resulting in the delivery of an unauthorised message to thousands of users.

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The breach, which occurred on 5 January was identified and shut down quickly, preventing further dissemination of the unauthorised message. EWN reported that no personal information was compromised and fortunately the hackers did not issue fake warnings. However, it serves as a pertinent reminder of the need to maintain the public’s trust in this warning system, especially during real emergencies (Read here and here).

ACT Riverine Flood Maps Revision

The ACT Government is making efforts to implement best practice flood risk management with recent updates to Canberra’s riverine flood maps.

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The maps incorporate the latest data, mapping and analysis tools and are designed to show potential flood hazard during a major flood. While Canberra is thought to have low flood risk with the only records of major floods recorded in Woden in 1971 and Lyneham in 2018, the action by the ACT Government is an important step to ensuring proper understanding of flood risk and management. The maps are publicly available on the ACTmapi website (Read here and here).

Warming Atmosphere Means More Flash Floods

The CSIRO and Bureau of Meteorology have released their fifth biennial State of the Climate report.

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The report focuses on revealing long-term climate trends such as increasing intensity of frequency of heatwaves and extreme fire weather conditions. The report detailed how the warming atmosphere is likely to be an important driver for increasing intensity of rainfall events linked to flash flooding. This is predicted to occur across Australia. International studies have revealed similar trends with disasters such as heat waves and flash flooding which were once considered rare in certain locations, being now three times more likely to occur with the warming trend (Read here and here).

Australian Tax Office (ATO) Flexible for Flooded Businesses

The Australian Tax Office has stated that it will assist small businesses in their tax affairs after being affected by a natural disaster. While tax issues are not a source of immediate stress during a disaster, it can add to the difficulty of recovering your business after the event. The ATO stated that if tax records have been destroyed, they will offer to help with their reconstruction, creating one less issue to deal with post-disaster (Read more here).[/su_spoiler]

Flood Mortalities on the Rise

Reinsurance companies Munich Re and Swiss Re have provided an analysis of disasters in 2018, highlighting the significant costs and mortalities from the year.

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In the analysis by Munich Re, it was revealed that 10,400 people around the world lost their lives in natural disasters in 2018. Mortalities due to floods increased from an average of 14% between 1980 and 2017 to an average of 35% in 2018. Floods, flash floods and landslides made up 46% of the total disasters from 2018. The Swiss Re report detailed that 2018 was the fourth most expensive year on sigma records for insurance. However, the total economic losses from disasters are estimated to be USD 155 billion which is down from USD 350 billion in 2017. The Centre for Research on Epidemiology of Disasters in its 2018 review of disasters events noted that floods have affected more people than any other natural hazard in the 21st century.  In addition, the World Economic Forum’s Global Risks Report 2019 is estimating more extreme weather for 2019. The report also details how spending on flood recovery is nine times higher than on prevention (Read more here, herehere and here).

Role of Gender in Flood Response

New research published in the International Journal of Environmental Research and Public Health investigated the differences in risk perception and subsequent action between genders in the event of a flood.

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The research was prompted by the outcome of the 2014 flood in Serbia which revealed that gender played a significant role in the success of management post-disaster. The study involved 2,500 interviews of men and women in 19 municipalities in Serbia. The results highlighted gender differentiation across several phases of the disaster cycle, with factors such as living conditions, demographic and economic attributes, behaviours and beliefs defining gender power relations. For example, women were found to be more realistic about hazard preparedness and their cares and concerns were more geared towards the household and family. Men were found to be generally more confident in their ability to manage a flood emergency. The study provided an insight into the differential roles typically taken on by men and women and how encouraging gender-related dialogue can promote these strengths in disaster contexts (Read more here).

Young People at Risk during Floods

Recent research by the Environment Agency and the British Red Cross indicates that people aged between 18 and 34 are the most at risk in a flood.

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This increased risk could be linked to a lack of knowledge regarding risk of flooding, specifically, not knowing if their homes are susceptible to flooding or how to adequately prepare if a flood warning was issued. In fact, it was revealed that less than half of under 35s would know how to respond to a flood warning (Read more here).

Social Capital Mitigates Flood Impacts

New research investigated the role of social capital as a mitigating tool against the impact of natural disasters in a flood-prone community.

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It was found that cultural factors and personal circumstances informed the strength of bonding social capital. Three cultural factors – Ethno-political organization, cooperative work and smooth interpersonal relationships – were found to mediate the strength of the bonding social capital and its translation into successful disaster management (Read more here).

Serious Games for Flood Mitigation

New research published in Water highlights the application of Serious Games for flood mitigation in the village of Millbrook, UK.

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In the study, a game provided participants with knowledge of the flood problem and asked users to apply inductive reasoning based on provided data to reach a solution. The Serious Game had the effect of increasing awareness and the prioritisation of flood management measures in Council meetings. As such Serious Games may be a useful tool in decision making (Read more here).

Regions Either Getting Wetter or Drier

A new study published in Geophysical Research Letters indicates that regions of the world are becoming skewed towards being wetter or drier.

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The study systematically analysed changes in record-breaking monthly rainfall events across the world with data taken from 50,000 weather stations. The data showed an increase in the number of record-wet months which was more evident in Central/East USA, Northern Europe and Russia. The increase in wet periods may have consequences for people in those affected areas relating to food security and safety of homes from flooding. However, in Central Africa the trend is shifting towards an increase in dry-months. This research further highlights the impact of human-induced climate change on climate patterns globally (Read more here and here).

Spatial Variation in Sea Level Rise Explained

A new study led by the Woods Hole Oceanographic Institution and published in Nature explains why sea level rise is not spatially consistent along coasts.

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The researchers examined sea level rise data taken from between 1900 and 2017. Sea level rise discrepancies ranged from 15 cm to 45 cm depending on the location along the North American coastline. The researchers have attributed most of this variation to a phenomenon called “post glacial rebound”. This refers to the effect of deglaciation of ice sheets in North America which caused the weighed down land mass to essentially “rebound” while other peripheral land masses began to sink. This effect is still seen today (Read more here and here).

Companies Ignore Climate Change Risk

A new study published in Nature Climate Change revealed that over 1,600 companies have not accurately characterised their climate change risk and management strategies.

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Despite this, more than half of the questioned companies expected that climate change would affect their production capacity and costs in the future. The study highlights five key areas where companies are falling down in their disaster management and that companies tend to employ a reactive rather than proactive adaptation strategy (Read more here).

Cloud-Based Flood Model

A cloud-based platform called Flood Cloud presents the next step in computational-intensive and cost-effective flood modelling.

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Users of Flood Cloud are able to perform model simulations in the cloud using software such as TUFLOW, HEC-RAS and Flood Modeller which allows for a greater number of simulations to be performed than on the local PC. The speed and performance through cloud-based modelling is advantageous as it allows for larger and more comprehensive datasets to be produced. This has application in real-time flood forecasting as it has potential to increase spatial predictions of flood risk from 1D modelling to 2D modelling. This advance can potentially allow for real-time flood forecasters to see forecasts of river levels and mapping of expected flood extents in real-time, allowing for more informed decision making during floods (Read more here).

Near-Real-Time Flood Forecasting

A new near-real-time flood forecasting approach has been made possible with the use of satellite precipitation products (SPPs).

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SPPs are precipitation data collected by satellites. This form of precipitation data is able to cover a large area for rainstorms and is capable of producing higher frequency data. The researchers used a discharge hydrograph to forecast the floods and used the results to map flood extent by incorporating SPPs into the rainfall-runoff model. It was found that this near-real-time flood forecasting approach using SPPs has potential to reduce the time of emergency responses to flood disasters by increasing the resolution and coverage of flood forecasting (Read more here).

River Levels Forecast Using Satellites

Researchers at the Technical University of Munich have developed a new method which makes it possible to monitor water levels of complex river basins using satellite data.

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The researchers integrated altimetric satellite data from short-repeat orbit and long orbit satellite missions to produce a meaningful time series of water level variations of the Mekong River in Vietnam. They used the Kriging approach on a series of satellite altimeter observations between 2008 and 2016 to extrapolate water levels. Integrating data from short-repeat and long orbit missions led to an increase in the probability of flood detection from 40% to 80% due to an increase in the temporal and spatial resolution of water level data (Read more here and here).

Google AI Increasingly Accurate at Predicting Floods

Researchers from Google at the Israel Institute of Technology and Bar-Ilan University have described a machine learning system that accurately predicts riverine floods.

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The researchers claim that machine learning for flood forecasting has the potential to exceed human-calibrated models which are inherently limited and are unable to match learned models in complex high-dimensional scenarios. The modelling requires significant calibration and is prone to error due to the high computational load and physics-based simulations. However, the researchers claim to have produced high resolution forecasts using the machine learning. This research presents a promising avenue for enhancing Google’s information systems in the future (Read more here and here).

Phone App Enables Real-Time Hazard Tracking

A mobile app developed by the European Project I-REACT allows users to share pictures and information on natural hazards in real-time.

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Users are given the ability to share geo-tagged images and data and learn about potential risks in their area. The app encourages information and reports to be verified by users to prevent the spread of false information. This app provides a means of retrieving and sharing information on disasters in the digital age and therefore may prove to be more useful in boosting awareness in disaster risk reduction in younger generations (Read more here).

Flood Mitigation Benefit Outweighs Cost

The National Institute of Building Sciences’ 2018 Interim Report on Natural Hazard Mitigation Saves has revealed that projects to reduce flooding will result in significant reductions in damage costs.

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The report is based on a study on natural hazard mitigation which aims to assist decision-makers in creating mitigation strategies. A series of benefit-cost analyses were done for U.S. Economic Development Administration funded flood mitigation projects across a range of infrastructure types such as roads, railways, and water and wastewater infrastructure. The benefit of implementing flood mitigation was found in most cases to greatly outweigh the cost of implementation. For example, proposed flood mitigation projects for roads were found to have an overall BCR of $2.05 saved per $1.00 invested and a water treatment facility project received an overall BCR of $9.70 saved per $1.00 invested (Read more here).

No Flood for the Pub

A UK pub in Southwold Harbour proved that proper preparation can greatly minimise the damage of an impending flood.

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Southwold Harbour is regularly subjected to flooding during high tides which can cause significant inconvenience and damages to the surrounding businesses. Warning of a high tide was circulated among local businesses, including the pub, 24 hours prior to the flood. The staff at the Harbour Inn used the time between receiving the warning to the time of the flood to move furniture away from areas with the potential to be inundated. This meant that when the flood hit the staff only had to wait for the waters to subside and clean the debris. With no damages, the pub was able to reopen again within hours. The general manager of the pub commented that this has become a common occurrence over the years. For businesses that are regularly subjected to these floods and receive adequate warnings, it is possible to take the proper precautions needed to reduce risk of damage. This reinforces the necessity for adequate flood warnings and for businesses to have a plan in place for when these events do occur (Read more here).

Introducing a Global Floodplain Dataset

New research published in Scientific Data presents the first, comprehensive, high-resolution dataset of Earth’s floodplains at 250 m resolution, called GFPLAIN250m.

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The researchers used the Shuttle Radar Topography Mission digital terrain model to produce geomorphic floodplain delineations. The dataset can be used for a range of applications such as flood hazard mapping, habitat restoration, development studies and the analysis of human-flood interactions. The researchers tested the dataset by performing a consistency analysis (Read more here).

Extreme Rainfall Events Connected Globally

A study published in Nature has revealed the presence of global-scale dependencies of extreme-rainfall events.

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The research found that certain areas of the world are connected or synchronized in terms of extreme-rainfall events. For example, south-central Asia and the European and North American and Southern Hemisphere extratropics were found to be linked by extreme-rainfall. The researchers’ analysis found that the creation and maintenance of these teleconnection patterns are caused by a mechanism called Rossby waves. Understanding these patterns and the underlying mechanism can be used to predict extreme weather events and weather forecasting on one continent based on recent weather events on another (Read more here and here).

Spain Taken to Court by EU for Flood Protection Failure

The European Commission is taking Spain to court as a result of its failure to comply with the EU rules on flood prevention under the Floods Directive (2007/60/.EC).

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The Floods Directive functions to manage the risk of floods to society. Spain was identified as neglectful, according to the EU, due to its failure to provide Flood Risk Management Plans which identify potential flood risks and how they would be managed for the river basin districts in the Canary Islands (Read more here).

Improving Flood Incident Planning

New research published in Science of the Total Environment shows how flood incident planning for emergency responders can be enhanced through the integration of multiple types of data.

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Tools and data used to assess flood impacts are generally considered in isolation, providing a limited picture of potential impacts. In this study, the researchers integrated analyses of flood hydraulics, transport accessibility and human safety in a case study of Galluzzo, Florence, Italy. This was done in an attempt to better understand the impact of flooding on pedestrians and drivers and determine how this information may be used to modify emergency routes and evacuation procedures. The analysis was found to provide an increased understanding of areas of high-risk and consequently how emergency services can prioritise evacuation (Read more here).

Tokyo Evacuation Centres Flood Prone

A poll conducted by Mainichi Shimbun has found that up to 38% of public evacuation centres in Tokyo are highly flood prone.

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Flooding of designated evacuation centres caused significant problems for evacuees during the floods of July 2018. In a response to global warming, cities, wards, towns and villages are required under the Flood Control Act to map and make publically available the areas which are at risk of a 0.1% AEP flood. With this knowledge, local governments are devising new procedures that will prompt residents to safely evacuate before a typhoon or flood occurs. However, the problem for evacuation centre safety remains a major challenge for municipal governments (Read more here).

Building Resilient Properties

Property flood resilience measures have been identified as essential for reducing flood damage costs and the recovery time of properties.

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The UK Department for Environment, Food & Rural Affairs with the assistance of BRE Group is taking steps to increase property flood resilience by implementing a new code of practice for construction projects in March 2019. The immediate aim is to retrofit currently at-risk properties with greater flood resilience features with potential in the future to be changes to building regulations. Examples of features that will be involved are flood-resistant features into new houses such as sustainable urban drainage systems, concrete floors and lifting electrical sockets and white goods (Read more here).

International Floods

There were 9 international floods reported across 12 countries throughout December 2018 and January 2019. At least 750 people died and over 260,000 were displaced.

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Internationally significant floods included:

Indonesia

At least 373 people died and 1,600 have been displaced after a tsunami hit the Sunda Strait in Indonesia on 22 December. The tsunami was triggered when a section of the Anak Krakatau volcano collapsed into the ocean.  There was no tsunami warning issued as it was triggered by a volcano rather than an earthquake. As a result, the tsunami struck almost without warning.  This event has prompted discussion surrounding the need for an early warning system for tsunamis that are caused by underwater landslides and volcanic eruptions (Read more here, here and here).

Sri Lanka

Flooding caused by long-term and severe rainfall in Sri Lanka has led to the displacement of 11,000 people and the deaths of two in the country’s north. Heavy rainfall began on 22 December which brought flash flooding that lasted through to early January. Maankulam in the Mullaitivu district received 365 mm rainfall in 24 hours. The worst-hit areas were the districts of Mullaitivu, Killinochchi, Mannar, Vavuniya and Jaffna (Read more here and here).

Philippines

Over 100 people have died and 80,000 people displaced after Tropical Cyclone Usman brought severe flooding and landslides throughout the country. Over 200 locations were affected with the Bicol Region one of the worst affected. Over 25,000 people were moved to 170 evacuation centres. Damage to agriculture saw a loss of $6.5 million. The storm which made landfall in the central province of Eastern Samar was not strong enough to be rated as a typhoon and therefore no tropical cyclone warning was issued because it was not perceived to be destructive. The number of deaths and number of people affected by the disaster showed it to be otherwise. Later in the month, one person died and 20,000 people were forced to evacuate as a result of flooding across the Davao Region. The flooding was due to severe rainfall which caused the Davao River to rise to 5.13 metres. The municipality of Hinatuan received a large amount of range, with 156 mm of rain in 24 hours (Read more here, here, here, here, here and here).

Thailand

Heavy rainfall and flooding caused by Tropical Storm Pabuk has led to the deaths of 12 people and displacement of 45,000 people. The storm made landfall in the province of Nakhon Si Thammarat which received 270.5 mm rain in 24 hours. Other provinces such as Sawi, Ko Samui, Narathiwat and Songkhla received less than 200 mm. Nearly 30,000 people were forced into evacuation shelters and the storm caused power outages to tens of thousands of homes (Read more here, here, here and here).

Argentina, Uruguay, Bolivia

Four people have died and 20,000 displaced after storms and flooding swept through Argentina, Uruguay and Bolivia. Heavy rainfall in Central and Southern Bolivia caused overflowing of the Picolomayo River and Cuevo Stream and 10,000 people were affected as a result. The city of Resistencia in Argentina received record-breaking rain of 224 mm in 24 hours. In Uruguay, the Yi River overflowed which caused severe flooding in Durazno and Sirandi del Yi (Read more here, here, here, here and here).

Malawi, Zambia and Mozambique

At least 20 people have died after Cyclone Desmond brought heavy rain and flash flooding to parts of Malawi, Zambia and Mozambique. Beira, the fourth largest city in Mozambique was one of the worst hit, receiving 277 mm of rain within 24 hours. In Zambia, the heavy rain caused the Luangwa River to overflow and the flooding destroyed 11 houses. Most of the fatalities occurred in Mozambique and some were due to people attempting to cross swollen rivers (Read more here, here, here, here and here).

Indonesia

At least 68 people have died and nearly 7,000 displaced on the Indonesian island of Sulawesi after extreme rainfall and high tides caused several rivers to overflow. Flooding in Gowa was also caused by the release of water from the Bili-Bili Reservoir. Some areas recorded over 300 mm of rain within 24 hours (Read more here, here and here).

Brazil

A tailings dam collapse in Minas Gerais, Brazil has resulted in the confirmed deaths of over 60 people and the evacuations of 40,000 people. More than 400 people are missing after the dam collapsed. The 86 metre dam, owned by mining company Vale was no longer in operation and was soon to be decommissioned. The collapse, which represents a major flood event, was also an environmental disaster as 11.7 million litres of mining waste was spilled out across the landscape (Read more here, here and here).

Saudi Arabia

At least 12 people have died after extreme rainfall brought flooding to western and north-western parts of Saudi Arabia.  Almost 300 people were rescued during the floods and 50 homes were reported to be swept away (Read more here and here).

Diary

Australian Rainfall and Runoff 2016 Practitioner’s Event (ARR2016)
Venue TBA
27 February, 2019

2019 Floodplain Management Australia Conference
Canberra, ACT
14 - 17 May, 20197
website

ASFPM 43rd Annual National Conference
Cleveland, Ohio
19 - 23 May, 2019
website

Resources

Flood Animation Shows Danger of Flood 
The Weather Channel uses immersive mixed reality to present the dangers of storm surge and floods (Website).

Floodplain Risk Management Guide

A guide to assist councils to transition to Australian Rainfall and Runoff (ARR2016) when developing and implementing floodplain risk management plans (Website).

2018 Review of Disaster Events
A summary of global disasters for 2018 published by CRED and UNISDR (Website).

Managing Uncertainty in Flood Forecasting
A research paper which aims to support flood forecasting practitioners in selecting appropriate uncertainty methods (Website).

Managing Disaster Risk in Southeast Asia
Report which provides a framework for assessing disaster risk management policies (Website)