Related - Floodplain Manager August 2019

Hawkesbury-Nepean Valley Regional Flood Study Released

Following the release of the Resilient Valley, Resilient Communities – Hawkesbury-Nepean Valley Flood Risk Management Strategy (Flood Strategy) in May 2017, the NSW Government has now released a new regional flood study for the valley.

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Some results of the study had previously been leaked to the media (FM July) warning that if a flood similar to the record flood of 1867 occurred that more than 90,000 people would need to be evacuated from the floodplain and more than 12,000 homes would be impacted by floodwater.  The valley has a long history of flooding with 130 moderate floods occurring since records began in the 1790’s. This study serves to update modelling prepared for the valley 20 years ago with more extensive and accurate data, new modelling techniques, and improved methods for considering the impacts of climate change. The uses of the study are broad reaching and include: providing publicly accessible flood information, informing emergency management and evacuation plans, informing regional and local council land use, allowing more accurate insurance premium pricing, and the ongoing exploration of flood mitigation options.

The study which covers the area between Bents Basin near Wallacia and Brooklyn Bridge, and falls mainly within Penrith, Hawkesbury, Blacktown and The Hills local government areas, modelled almost 20,000 possible flood events using Monte Carlo simulation. It used a quasi two-dimensional RUBICON hydraulic model but the report recommends full two dimensional modeling of the river in the future.

The full study can be accessed here

(Read here, here and here).

Thousands in Temporary Townsville Accommodation Six Months On

According to July figures from the Queensland Reconstruction Authority only about 1,400 of the 3,300 north Queensland homes damaged by floodwaters (FM February) have been repaired, forcing thousands of residents to remain in temporary accommodation.

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A reported 8,000 houses were damaged in the monsoon that ravaged Townsville, with the city loosing 10 per cent of its housing stock causing more than half of those residents to be displaced. The Insurance Council of Australia (ICA) said almost half of the 12,850 home building claims had been closed, with work starting on 89% of the 1,471 properties reported to be uninhabitable. However, for some residents, waiting for claim decisions and disputes with insurance companies over the scope of works have left  them in limbo with no certainty about when they will be able to return home. Reports state that more than 600 claims are in internal dispute resolutions with insurance companies. Shortages of tradespeople like carpenters, plasterers, painters and tilers in the region, and complications such as pre-existing structural issues with properties are blamed for the time delays (Read here).

Townsville Flood Loss Estimates Revised Upwards

The insurance and reinsurance market loss to property lines of business from the Townsville flooding has been raised by 16% to $1.2 billion.

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PERILS AG, the Zurich based catastrophe loss data provider who presented this figure, only reports on property related insured damages in Australia. Therefore it is likely that the $1.2 billion total insurance and reinsurance industry loss to all lines of business reported by the Insurance Council of Australia (ICA) is too conservative, and the total is expected to rise. PERILS industry loss estimate has already increased by 27% since it first reported on the Townsville floods.  Some in the insurance industry are suggesting that very soon North Queensland will become uninsurable for natural hazards (Read here and here).

Game Helps Kids Make Parents Disaster Resilient

A Macquarie University PhD student’s innovative education intervention board game enables children to engage with parents and build disaster resilient households.

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Avianto Amri’s PhD research has produced a new board game called PREDIKT designed to empower children at home. Initial results suggest that the education intervention is successful in motivating parents to discuss householder preparedness with their children, and has been used by agencies and practitioners across Australia, Indonesia, Malaysia and Thailand. The game forms part of a broader toolkit, which includes worksheets, templates, tips and preparedness items for multiple hazard types, to further strengthen disaster preparedness through interactive learning. It is hoped that participation in the game will encourage children to become more mindful of protecting themselves and others in emergencies, and to become agents of change for their communities (Read here).

Climate Change Wave Changes will impact Coasts

As part of the Coordinated Ocean Wave Climate Project, Australian research organisations observed a range of global wave models under a variety of future climate scenarios and found that wave conditions are likely to change along 50% of global coastlines.

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The study built on the findings of recent research which suggests that average wind speeds have risen by 1.5 metres per second, and wave heights have increased by 30cm in the past 30 years. The researchers were interested in how projected future changes in atmospheric circulation, could alter wave conditions globally, and found that conditions varied by region. For instance, different regions may experience an interplay of changes in wave height, direction and period which could in turn alter natural sand drift dynamics and increase the risk of wave-driven flooding. This study helps bring to the fore wave condition changes as part of the complex interplay associated with sea level rise which could cost at estimated $20 trillion worldwide annually by 2100 under a 2oC warmer climate (Read here  and here).

Kempsey SES Hold Memorial Service to Honour the Six People Who Lost Their Lives in the 1949 Flood

The NSW SES united the community of Kempsey to mark the 70th anniversary of the 1949 flood with a memorial service and historic photo exhibition.

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The 1949 flood reached 8.52 metres at the Kempsey gauge, drowned more than 15,000 livestock and washed away 53 homes and businesses, with many more properties and buildings severely damaged. Community members gathered at a commemorative plaque at Clyde Street Mall to remember the six people who lost their lives and reflect on what can be learnt from the flood.  The flood was estimated to be about a 1% AEP level and was followed in 1950 by a flood of only slightly lesser magnitude which was far less damaging because buildings destroyed in the 1949 flood were not rebuilt (Read here).

US Farmland Has Been Flooded For Five Months

Since late February, approximately 222,500 hectares of land, of which half is farmland, has been underwater in the rural Yazoo backwater area of the lower Mississippi delta, USA.

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Although flooding is not uncommon in this region, the compounding effects of a high Mississippi River, which remained near or above flood stage for the longest span since 1927, and heavy rainfall resulted in lingering backwater that has inundated the region and threatens the agricultural based economy. Flood prevention measures associated with the Yazoo Backwater Project that were approved by congress in 1941 included a system of levees, canals and drainage structures and drainage pumps. However, construction of the drainage pumps never occurred as the Environmental Protection Agency (EPA) vetoed the pumps in 2008, citing a threat to wetlands and wildlife in this remote part of Mississippi. The seemingly relentless floodwaters have sparked a review of the veto decision by the EPA, restoring hope to residents that the much needed pumps may be constructed. However, many residents feel as though their rural community has been left out of the national disaster dialogue stating: “Because no one’s died from this, and we live in such a remote place, it doesn’t seem to be important to national news” (Read more here).

Flood-Prone Areas in US Have Fastest Housing Growth

A study by New Jersey research group Climate Central, has found that in the USA’s coastal states flood-prone areas have seen the highest rates of home construction since 2010, despite the increasing risk posed by climate change.

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The researchers in this study estimated the 10-year flood risk zone area size for the year 2050 and calculated the number of homes built there since 2010. Results showed that for eight states the percentage increase in homes built in the flood zone exceeded the rate of increase in the rest of the state (Read more here ).

Global Water Map Could Warn of Future Floods

Researchers at the Texas A&M University, USA have created a new global map of freshwater hydrography which can be used to accurately predict future flooding events around the world.

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MERIT Hydro, uses complex computer algorithms to determine the shape of millions of Earth’s rivers, lakes, and canals and also provides a hydrologically consistent map of Earth’s topography. Reflecting on the consensus that the intensity of rainfall events is likely to increase with climate change, MERIT Hydro produces a high-fidelity representation of the flow paths of water to allow the prediction of timing and magnitude of river flow, including floods (Read more here ).

Scramble to Prevent Dam Break

Rescue workers in the UK worked tirelessly to stop the collapse of a dam in the Peak District and prevent 1.2 million tonnes of water flooding the town of Whaley Bridge below.

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The dam was built in 1831 and holds back water from the Toddbrook reservoir. However, after a period of heavy rain, water pouring over the spillway began eroding the concrete, leaving the structural integrity of the dam in jeopardy. A local volunteer with the Canal and River Trust raised the alarm after finding a lone employee battling to rake debris clear of pumps and frantically adjusting valves. Closer inspection of the dam prompted the evacuation of thousands of residents from surrounding areas, while at the dam a RAF helicopter deposited hundreds of bags of sand and aggregate to shore up the loose concrete. Rescue teams scrambled to gather 12 pumps and installed steel pipes to channel water from the reservoir allowing 700,000 tonnes of water to be pumped out in four days; whilst boat crews cleared clogged pipes of weeds and debris.  The reservoir level will be lowered to allow engineers to inspect damage, and it is expected that repairs could take up to a year to complete. Many residents are concerned that the close call was a warning that the dam may not have been properly maintained (Read more here ).

Critical Infrastructure and Flood Resilience: Cascading Effects Beyond Water

A study published in WIREs Water presents a conceptual framework integrating aspects of disaster risk, hazard, vulnerability and resilience with critical infrastructure.

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The relationship between flood risk, protection, economic development and human behaviour is widely regarded, yet still the interaction of knowing about disaster and knowledge-based behaviour is lesser known. Historically, research tends to focus on disaster mortality and general damage as monitoring indicators for understanding disaster risk. This paper suggests that critical infrastructure (CI) such as energy, transport or water supply should be considered as a cascade effect in flood related disaster resilience frameworks. This is because CI often exists as large-scale interconnected networks and has broad reaching impacts well beyond the area of the flood. The researchers propose a flood resilience framework that integrates aspects of vulnerability and exposure of traditional risk approaches for multiple stakeholders and property types that are interrelated with locations of CI assets (Read more here ).

International Floods

There were 29 international floods reported across 21 countries throughout August 2019. At least 248 people died and over 225,000 were displaced.

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Internationally significant floods included:

Pakistan

Monsoon rain and floods in Pakistan‘s Sindh Province have left 26 dead and displaced 130 people. Karachi recorded 130mm of rain in 24 hours causing damage to many buildings and inundating streets. Elsewhere, ten people have died in the Khyber Pakhtunkhwa Province as a result of flash floods and landslides. (Read more here, here, and here).

China

Flooding in China’s north-eastern Heilongjiang Province has displaced around 11,400 people and damaged over 2,500 homes. The Ashi River has been above warning-level since late July affecting areas around Harbin City. An estimated 563,000 hectares of crops in the province have been affected as well as 30 rail networks with direct economic loss thought to be in excess of $465 million (Read more here).

India

The Indian states of Andhra Pradesh, Assam, Bihar, Gujarat, Rajasthan, Maharashtra, Karnataka and Karala have been severely hit during this year’s monsoon season spanning through much of July and August. Approximately 500mm of rain fell in 24 hours in one of the worst hit regions of Gujarat. At least 53 people have died and 5,000 people have been evacuated from low-lying areas believed to be under threat from the overflowing Vishwamitri river in the countries west. In Andhra Pradesh 17,000 people have been displaced as heavy rain caused the Godavari River at Dowlaiswaram in East Godavari District to rise above 15 metres flooding low-lying areas. In the southwestern state of Karnataka floods have displaced around 2,225 people, damaged 974 houses and almost 87,000 hectares of crops. (Read more here, here, here, here, and here ).

Yemen

At least 12 people have died in mudslides as a result of flash floods following heavy rainfall in the northwestern Al Mahwit governorate of Yemen. Torrential rains and flash flooding has affected other districts in early August, with at least 120 families displaced. (Read more here).

Myanmar

Torrential rain has triggered a massive landslide in Paung Township, Mon State, Myanmar killing 41 people and destroyed several homes. Elsewhere in the state, flooding from the Attayan River has displaced 25,000 people. (Read more here).

Vietnam

Flooding in central and southern Vietnam since 8 August has led to the deaths of 10 people and displaced 2,000 people. Parts of Vietnam were hit by Tropical Storm Wipha which brought heavy rains to the north of Vietnam on 03 August 2019, causing nine deaths and damaging 284 houses in Thanh Hoa and Lang Son provinces. Rivers in some areas reached record high levels. (Read more here).

Sudan

Floods in Sudan have killed 54 people predominately as a result of housing collapse as flood waters destroyed at least 22,600 homes. Flooding has also affected areas around the capital, Khartoum, where 155mm of rain fell on 9 August. Flood waters have destroyed and damaged numerous schools, mosques and medical centres across the country. (Read more here and here).

Diary

Adapting Swansea: Planning for Future Flood Risks
Where: The Swansea Centre, 228 Pacific Hwy, Swansea NSW 2281
When: 4pm-6:30pm, 6 August, 2019
For more information visit here

2019 International River Symposium
Where: Brisbane, Australia
When: 20-24 October 2019
For more information visit here

2019 The International Emergency Management Society (TIEMS) Annual Conference
Where: Goyang, Korea
When: 12-15 November, 2019
For more information visit here

2020 Floodplain Management Australia Conference
Where: Empire Theatre, Toowoomba, QLD
When: 19-22 May, 2020
website

2020 Association of State Floodplain Managers (ASFPM) Annual National Conference
Where: Fort Worth, Texas, USA
When: 7-12 June 2020
For more information visit here

2020 International Conference on Flood Management
Where: The University of Iowa, Iowa City, Iowa, USA
When: 17-19 August, 2020
For more information visit here

Resources

NSW SES Helps Residents Interpret and Prepare for the Findings of the Hawkesbury -Nepean Valley Regional Flood Study

NSW State Emergency Services (SES) has published a webpage that decodes the findings of the Hawkesbury -Nepean Valley Regional Flood Study by each region whilst providing helpful preparation tips and guides to understanding flood risk. (Click here).