Flood Risk

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<div id="lightbox0">GUEST OBSERVER</div>
As Hurricane Harvey made landfall north of Corpus Christi, this Category 4 hurricane left devastation in its wake.
CoreLogic estimates that the total residential insured and uninsured flood loss for Hurricane Harvey is between $25 billion and $37 billion.
In the days before making landfall, the hurricane rapidly intensified, transforming itself from a small tropical storm of little concern, to now, what we consider to be one of the most devastating hurricanes to hit the United States.
Yet, the real characteristic that sets Hurricane Harvey apart from other hurricanes is the unprecedented flooding that resulted, with record setting rainfall reaching upwards of 50 inches in a single location.
Subsequently, the enormous geographic breadth of the flood area is beyond comparison to any recent hurricane or flood event in the U.S. CoreLogic analysis estimates that 70 percent of the flood damage from Hurricane Harvey is uninsured, highlighting an insurance gap that leaves many of those impacted uninsured.  
<a href="https://www.propertyobserver.com.au/images/2017/09/15/Screen%20Shot%202017-09-15%20at%209.01.22%20AM.png" target="_blank">Click to enlarge</a>
<img src="https://www.urban.com.au/images/2017/09/15/Screen%20Shot%202017-09-15%20at%209.01.22%20AM.png" alt="">
Naturally occurring catastrophic events can be tipping-point events, where a failure in one area can quickly cascade into interconnected failures.
We cannot control the timing of low-probability catastrophes (and the rare occurrence of more than one event in a short period, such as Hurricane Irma on the heels of Hurricane Harvey, making landfall in the continental United States) of this severity but can improve our ability to respond, and subsequently rebuild.
Having a comprehensive and granular understanding of risk powered by data and analytics is critical to that. We look to do this through improvements gained largely though the maintenance of better insurance exposure data sets, and the introduction and acceptance of catastrophe risk loss models that can simulate the occurrence of large catastrophic events.
In 1992 when Hurricane Andrew made landfall, it took months for the government and insurance industry to accurately quantify the losses from this event and this delay increased the losses in both financial and human terms. However, in the wake of Hurricane Katrina, the loss severity was rapidly assessed, quickly putting into motion large scale government and private restoration efforts.
In short, as bad as the effects were from Hurricane Katrina, they could have been significantly worse.
The widespread flooding from Hurricane Harvey, caused by storm surge and inland flooding, highlights the challenge of flood risk to properties in the United States.
Since we cannot influence the timing and severity of natural catastrophes, we need to focus on resilience – our collective ability to rebuild and restart businesses and lives.
Insurance is an important part of our resilience because insurance provides the funds necessary to restore the damage to capital from these events. Hurricane risk modeling became accepted after Hurricane Andrew highlighted weaknesses in our ability to respond to large urban catastrophes, and this adoption has led to faster restoration of lives and livelihoods after hurricanes.
Flood risk modeling is a much more complex data and analytic challenge than hurricane risk modeling, but the greater availability of location data sets and grid computing in 2017 have improved our ability to respond to flood disasters.
If we characterize the last phase of risk resilience improvement as the era of catastrophe modeling data and analytics, the next era will be known as the era of big data and grid-computing analytics. And one where we began to actively manage flood risk in the United States.
CoreLogic's Tom Larsen can be contacted <a href="https://www.corelogic.com/default.aspx" target="_blank">here</a>.
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jchancellor-FAypfDUnLy

70 percent of the flood damage from Hurricane Harvey is uninsured

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Brisbane suburbs affected by the 2011 flood are outperforming the rest of the city, new research shows.
RiskWise Property Research said that of the 20 suburbs affected by floods, 19 (or 95%) have outperformed the rest of the city in terms of housing prices.
The location of these suburbs continues to make them attractive to buyers, says RiskWise CEO Doron Peleg.
“After the 2011 floods the perception among property buyers was these areas would be looked at negatively and prices would fall, or at least deliver very poor capital growth” Peleg said.
“But our research has shown the reality is completely different and the demand for them has eclipsed the negative perception.
“This is because these high-flood areas are truly well located on the river which is in high demand.
“Also, statistically floods like those in 2011 are a once-in-a-50-year event and that makes these homes a risk people are willing to accept.”
<img src="https://res.cloudinary.com/dz9xllyip/image/fetch/c_scale,w_580,q_auto:good/https://s3-ap-southeast-2.amazonaws.com/po.images/2018/5/5/Brisbane%20Flood%20Prone%20Area%20v2.0.jpg" alt="">
Peleg said many of these areas are subject to rezoning which makes them attractive to developers.
He said when considering buying property in a flood area purchasers should do a risk assessment of the suburb, the type of property they want to buy as well as what the risk for the specific property was.
“Also, that's why we have insurance companies. And while they have revised their product offerings and premiums, which no doubt will be quite high, it is still possible to get insurance.”
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jonathanchancellor-7SQnKwU6yx

Suburbs most affected by Brisbane floods outperforming rest of city

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GUEST OBSERVER
It’s March 2018. A massive storm has hit Sydney’s northern beaches. Luckily no one is hurt, but the floodwaters take days to drain away and the economic impact is serious.
Reporters will tell the story over and over again: how much damage this torrential rain did. But where have we heard that before? Well, the list includes: both Queensland and New South Wales this year, Sydney in 2016, Gold Coast in 2015, Bundaberg in 2013, Queensland in 2012 and Brisbane in 2011.
We are starting to understand we will be hit by ever-increasing storms and floods. The risk is especially high in years when La Nina makes her appearance.
We also know good urban design can reduce the impacts.
Measures to soften the blow
Sydney’s Green Grid is planned to increase the resilience of the city and its residents against flooding and other climate impacts. The grid is designed to connect hydrological and ecological systems or, better, to reconnect these systems to boost their capacity to deal with sudden and severe impacts.
Spaces need to be created in the city for storing water during and directly after a flood. This will stop water from drowning people, flooding houses or destroying public property. These storages can take the form of water squares, temporary storage on ovals or parking areas, basins or gardens on rooftops, and swales along roads.
These measures are well known to be effective and together form an urban sponge system. All we need to do is to create more of these places to increase the capacity to take up water, then release it when safe to do so.
In every city certain areas play a crucial role in increasing, or not decreasing, water-storage capacity. These areas are on the edge of the waterscape and the cityscape. Increasing water storage here prevents bigger problems elsewhere.
What this means for Marrickville
If these places become built-up and can no longer effectively store floodwaters, the impact downstream is disastrous. Carrington Road in Sydney’s Marrickville is a prime example. This inner-city area flooded in 2012, leaving cars floating, houses flooded and people’s belongings lost or ruined.
The analysis and the facts are clear, even neatly mapped out by the New South Wales state government. No misunderstanding there. The safest option is not to build up this area.
<img src="https://images.theconversation.com/files/192763/original/file-20171101-13406-1i4u642.png?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt="">
The flood-prone zone in Marrickville. NSW government, 2015
However, if Sydney wants to become a global city, we need to get used to urban environments with higher densities – these have all kinds of advantages. Immediate benefits include better public transport, higher level of amenities and proximity to a dynamic economic environment which generates jobs for the local population. Higher density also prevents occupation of green spaces outside the city and unnecessarily long commuting times for people housed even further away from the city.
This means no densification of existing neighbourhoods is a poor option. However, a proposal to build 20 buildings with 2,600 units in the flood-prone zone in Marrickville has raised eyebrows.
The local council is opposing the “monstrous” scale of the development. The state Labor opposition has joined the battle against this “mega-apartment project”.
But much of the opposition is not for the right reasons. The Inner West Council’s Carrington Road area planning proposal seems to prioritise density over flood risk. When the Cooks River overflows again, as it will, the floods will be even more severe.
Planning should be aiming to create a symbiotic situation, in which a higher-density development and flood mitigation are complementary. The challenge is to marry two seemingly contrasting ambitions: to increase density and yet not increase the vulnerability to floods.
Well-structured density makes all the difference
To achieve this, the first consideration would be to see the area as a flood reservoir where water can temporarily be stored. If this reservoir is then also used to clean rain runoff and grey water from the apartment buildings, it would function as a green space, water treatment and flood remediation space all at once.
What if one large natural wetland could be created, which could capture the water from the Cook River during a flood, but could also clean the rain and grey water from the buildings? The new buildings would not have to suffer from hazards such as flooding because the site design has anticipated the risk.
As an example, imagine a Borneo-Sporenburg type of setting in which the water space surrounds the built-up area. Even with mostly low-rise housing, the development could still reach a high density of around 150 dwellings per hectare.
Applied to Carrington Road, this would imply around 1,200 dwellings can be built in a low-rise setting. Adding two internal superblocks to this development would create another 500 units and only one high-rise building (instead of 20) would then be needed to make it to 2,600 dwellings in the whole development.
The new neighbourhood could form a very sustainable, almost circular system in which waste water, waste heat and waste materials could all be reused for the apartments and dwellings, and in the wetland reservoir. This way the wetland becomes an attractive green space for residents to use. It’s then a green space that not only accommodates the eventual flood, but also regulates the temperature of the urban environment, creating cooler places in summer.
<img src="https://counter.theconversation.com/content/86608/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">An interesting milieu could emerge here. If the buildings were built on stilts and lifted above the reservoir, wildlife, ecology and water could exist undisturbed under and around the buildings. The result would be a flexible infill development that preserves green and public space, and which is ready for extreme weather or climate conditions.
Rob Roggema, Professor of Sustainable Urban Environments, University of Technology Sydney
This article was originally published on <a href="https://theconversation.com" target="_blank">The Conversation</a>. Read the <a href="https://theconversation.com/higher-density-in-a-flood-zone-heres-a-way-to-do-it-and-reduce-the-risks-86608" target="_blank">original article</a>.
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j.ballantyne1990-6AQqhLzZaK

How to reduce the risks higher density in a flood zone: Rob Roggema

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GUEST OBSERVATION
A flood-ravaged Townsville has captured public attention, highlighting the vulnerability of many of our cities to flooding. The <a href="https://www.propertyobserver.com.au/https://www.abc.net.au/news/2019-02-15/queensland-floods-special-climate-statement/10816184" target="_blank">extraordinary amount of rain</a> is just one aspect of the disaster in Queensland’s third-biggest city. The flooding, increasing urban density, the management of the Ross River Dam, and the difficulties of dealing with byzantine insurance regulations have left the community with many questions about their future.
These questions won’t be resolved until we enhance the resilience of cities and communities against flooding. Adaptation needs to become an integral part of living with the extremes of the Australian environment. I discuss how to design and create resilient urban landscapes later in this article.
Flood risk and insurance
Another issue that affects many households and businesses is the relationship between insurance claims and <a href="https://www.propertyobserver.com.au/https://www.preventionweb.net/news/view/63766" target="_blank">1-in-100-year flood event overlay maps</a>. Projected rises in flood risks under climate change have led to <a href="https://www.theguardian.com/australia-news/2019/feb/20/townsville-homes-may-become-uninsurable-due-to-flooding-from-climate-change" target="_blank">concerns that parts of Townsville and other cities will become “uninsurable”</a> should the costs of cover become prohibitive for property owners.
Council flood data <a href="https://www.propertyobserver.com.au/https://www.preventionweb.net/news/view/63766" target="_blank">used for urban planning and land-use strategies</a> is also used by insurers to assess the flood risk to individual properties. Insurers then price the risk accordingly.
However, in extraordinary circumstances, when the flooded land is actually larger than the area marked by the flood overlay map, complications emerge. In fact, that part of the community living outside the map’s boundaries is considered flood-free. Thus, those pockets of the community may have chosen not to have flood insurance and not have emergency plans, which leaves them even worse off after floods. This is happening in Townsville.
Yet this is nothing new. Many people experienced very similar circumstances in 2011. Flood waters covered as much land as Germany and France combined. Several communities were left on their knees.
Notwithstanding the prompt and vast response of the federal government and Queensland’s state authorities, a few years later Townsville is going through something alarmingly similar.
Adaptation to create resilient cities
To find a solution, we need to rethink how to implement the <a href="https://www.disaster.qld.gov.au/dmg/Prevention/Pages/3-5.aspx" target="_blank">Queensland Emergency Risk Management Framework</a>. That is no easy task. However, it starts with shifting the perspective on what is considered a risk – in this case, a flooding event.
Floods, per se, are not a natural disaster. Floods are part of the natural context of Queensland as can be seen below, for instance, in the <a href="https://www.qhatlas.com.au/content/channel-country" target="_blank">Channel Country</a>.
<a href="https://images.theconversation.com/files/261144/original/file-20190227-150724-xvwvfx.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/261144/original/file-20190227-150724-xvwvfx.JPG?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
Floods are part of the Australian landscape. Here trees mark the seasonal riverbeds in the Queensland outback between Cloncurry and Mount Isa. Cecilia Bischeri, Author provided
The concept of adaptation as a built-in requirement of living in this environment then becomes pivotal. In designing and developing future-ready cities, we must aim to build resilient communities.
This is the ambitious project I am working on. It involves different figures and expertise with a shared vision and the support of government administrations that are willing to invest in a future beyond their elected term of office.
Ideas for Gold Coast Resilientscape
I live and work in the City of Gold Coast. Water is a fundamental part of the city’s character and beauty. In addition to the ocean, a complex system of waterways shapes a unique urban environment. However, this also exposes the city to a series of challenges, including flooding.
Last September, <a href="https://www.gchaveyoursay.com.au/industryhub/news_feed/updated-flood-overlay-maps" target="_blank">an updated flood overlay map</a> was made available to the community. The map takes into account the projections of a 0.8 metre increase in the sea level and 10% increases in storm tide intensity and rainfall intensity.
These factors are reflected in the 1-in-100-year flood overlay. It shows undoubtedly that the boundaries between land and water are changeable.
Building walls between the city and water as the primary flood protection strategy is not a solution. A rigid border can actually intensify the catastrophe. New Orleans and the <a href="https://soundwaves.usgs.gov/2006/01/" target="_blank">levee failures</a> during the passage of Hurricane Katrina in 2005 provide a stark illustration of this.
Instead, what would happen and what would our cities look like if we designed green and public infrastructures that embody flooding as part of the natural context of our cities and territory?
The current project, titled RESILIENTSCAPE: A Landscape for Gold Coast Urban Resilience, considers the role of architecture in enhancing the resilience of cities and communities against flooding. The proposal, in a nutshell, explores the possibilities that urban landscape design and implementation provide for resilience.
RESILIENTSCAPE focuses on the Nerang River catchment and the Gold Coast Regional Botanic Gardens, in the suburb of Benowa. The river and gardens were adopted as a case study for a broader strategy that aims to promote architectural solutions for a resilient City of Gold Coast. The project investigates the possibility of using existing green pockets along the Nerang River to store and retain excess water during floods.
<a href="https://images.theconversation.com/files/261354/original/file-20190228-150721-xt0v13.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img src="https://images.theconversation.com/files/261354/original/file-20190228-150721-xt0v13.jpg?ixlib=rb-1.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" alt=""></a>
Gold Coast Regional Botanic Gardens is one of the green areas along the Nerang River that could be used to store and retain flood water. <a class="source" href="https://commons.wikimedia.org/wiki/File:Gold_Coast_Regional_Botanic_Gardens_(08).jpg" target="_blank">Batsv/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/" target="_blank">CC BY-SA</a>
These green spaces, however, will not just serve as “water tanks”. If mindfully planned, the green spaces can double up as public parks and facilities. This would enrich the community’s social realm and maximise their use and return on investment.
The design of a landscape responsive to flooding can, by improving local urban resilience, dramatically change the impact of these events.
The goal of creating urban areas that are adaptive to an impermanent water landscape is the main driver of the project. <a href="https://www.fastcompany.com/3068730/this-new-orleans-neighborhood-is-fighting-flooding-by-welcoming-it" target="_blank">New Orleans</a> after <a href="https://theconversation.com/disappearing-acts-reflecting-on-new-orleans-10-years-after-katrina-46834" target="_blank">Hurricane Katrina</a> and<a href="https://archpaper.com/2017/10/five-years-sandy-nyc-update-flood-resilience-zoning/" target="_blank"> New York</a> after <a href="https://theconversation.com/frankenstorm-sandy-wreaks-havoc-on-nyc-floods-cities-10420" target="_blank">Sandy</a> are <a href="https://www.nisconsortium.org/nisc-activities/neworleansfloodresexp/" target="_blank">investing heavily in this direction</a> and promoting <a href="http://www.rebuildbydesign.org/" target="_blank">international design competitions</a> and community participation to mould a more resilient future. Queensland, what are we waiting for?

Cecilia Bischeri, Lecturer in Architecture, Griffith University
This article is republished from <a href="http://theconversation.com" target="_blank">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/townsville-floods-show-cities-that-dont-adapt-to-risks-face-disaster-112607" target="_blank">original article</a>.
Main photo: Flooded suburbs of Brisbane 
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