tag:theconversation.com,2011:/us/topics/flood-models-32981/articlesFlood models – The Conversation2023-09-08T15:58:16Ztag:theconversation.com,2011:article/2131642023-09-08T15:58:16Z2023-09-08T15:58:16ZGreece’s record rainfall and flash floods are part of a trend – across the Mediterranean, the weather is becoming more dangerous<p>Recent images of the <a href="https://www.theguardian.com/world/2023/sep/07/a-biblical-catastrophe-death-toll-rises-to-four-as-storm-daniel-lashes-greece">devastating flash floods caused by Storm Daniel</a> in Greece hit close to home literally and figuratively. As a Greek who has completed a PhD and worked for the past eight years on <a href="https://www.gre.ac.uk/people/rep/faculty-of-engineering-and-science/ioanna-stamataki">flash floods</a>, the scenes unfolding across my homeland are painfully real: a stark reminder of the broader environmental challenges we face both on a local and a global scale.</p>
<p>These unprecedented flash floods were triggered by rainfall from the arrival of Storm Daniel on Monday September 4 which also affected Turkey and Bulgaria. The following day, in the village of Zagora, a record-breaking 754mm of rain fell <a href="https://www.meteo.gr/article_view.cfm?entryID=2913">in just 18 hours</a>, leaving parts of the region of Thessaly in crisis and unable to respond. </p>
<p>To put this in perspective, London gets about 585mm of rain over the course of a year while Thessaly gets 495mm, meaning that on Tuesday September 5, about 1.5 years’ worth of rain fell in 18 hours. Imagine the most torrential rain you have ever experienced, perhaps a cloudburst lasting 20 minutes or so. Now imagine it raining that hard but without pause for an entire day.</p>
<p>Flash flooding is short in duration but extremely intense, and typically happens within six hours of heavy rainfall. Unlike regular floods, which develop more slowly and can be predicted in advance, flash floods catch people off guard due to their rapid onset and are rarely recorded in the field.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Annotated map of central Greece" src="https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=386&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=386&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=386&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=485&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=485&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547267/original/file-20230908-25061-jdzebm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=485&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Greece’s daily rainfall record was broken with 754 mm of rain in the village of Zagora – more than double the UK’s equivalent record.</span>
<span class="attribution"><a class="source" href="https://meteo.gr">National Observatory of Athens/meteo.gr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>Catastrophic effects</h2>
<p>Across the three affected countries the floods have killed <a href="https://www.theguardian.com/world/2023/sep/07/a-biblical-catastrophe-death-toll-rises-to-four-as-storm-daniel-lashes-greece">at least 18</a> people, with many others seeking refuge on their rooftops. There are ongoing power and water outages, infrastructure has been damaged, houses and even <a href="https://www.youtube.com/watch?v=hKGrc--tNyM">entire villages</a> have been completely submerged. </p>
<p>I asked Andrew Barnes, an academic at the University of Bath with expertise in <a href="https://researchportal.bath.ac.uk/en/persons/andy-barnes">using AI to analyse extreme events</a> why this event was so exceptional. He told me that throughout Tuesday, a strong low-pressure centre formed across the south of Greece creating a large rotating weather system known as a <a href="https://education.nationalgeographic.org/resource/hurricanes-cyclones-and-typhoons-explained/">cyclone</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1699008805051269370"}"></div></p>
<p>This cyclone carried large rain clouds from both the Mediterranean and Aegean Sea between Greece and Turkey. But it did not dissipate, and instead its low-pressure centre moved southwest and settled just south of Italy, with its bands of rain clouds also moving south and covering most of mainland Greece.</p>
<h2>Trending across the region</h2>
<p>It is crucial to emphasise that flash floods are not confined to Greece alone. They are in fact part of a broader pattern of extreme weather that has become more intense and frequent across the Mediterranean region.</p>
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<a href="https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1067&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1067&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1067&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547268/original/file-20230908-19-diwfhg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author’s friend saw this flooding in the village of Chorto.</span>
<span class="attribution"><span class="source">Irini Arabatzi</span></span>
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<p>Researchers who looked at <a href="https://www.nature.com/articles/s41467-018-04253-1">150 years of flood data</a> in the Mediterranean found that most were flash floods, with their highest occurrence during the summer and autumn months. The region is <a href="https://www.mdpi.com/2073-4441/15/1/119">particularly</a> <a href="https://doi.org/10.3390/land10060620">susceptible</a> to these floods due to the combined effects of climate change and urbanisation. The latter has increased urban development in flood-prone areas and increased impervious surfaces (like roads and pavements), preventing the natural absorption of water into the ground.</p>
<p>The Intergovernmental Panel on Climate Change’s chapter on the Mediterranean region issued a <a href="https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_CCP4.pdf">warning</a> that extreme rainfall events are going to occur more often and be even more intense, elevating the risk of flash floods. This warning, in combination with records of flash floods in 2023 in Spain, Italy, Turkey, Bulgaria, France and Greece, underscores the urgent need for proactive measures to address these climate-related challenges. </p>
<h2>Research is advancing</h2>
<p>Flash floods might be rare, but they are severe enough to be a matter of significant concern. Fortunately, research has advanced considerably in recent years. We’re now better able to forecast <a href="https://www.mdpi.com/2073-4441/12/2/570">when flash floods might happen</a>, which areas might be <a href="https://www.mdpi.com/2072-4292/12/1/106">susceptible</a>, and to assess their impact <a href="https://www.sciencedirect.com/science/article/pii/S0160412019314485?via%3Dihub">in real-time</a>. </p>
<p>My colleagues and I are working on a <a href="http://www.docuflood.uk/">project</a> that combines historical documentary sources and modern hydraulic modelling. This way we can shed light on past floods and better understand the risks they pose, helping us design effective mitigation strategies for the future. Practically, in the case of a flash flood some basic but very important actions can be found on the poster below. </p>
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<a href="https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="infographic with important actions to take" src="https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=141&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=141&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547269/original/file-20230908-29-y6wdtf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=141&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tips from a flash floods expert.</span>
<span class="attribution"><span class="source">Ioanna Stamataki</span></span>
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<p>A complete eradication of flooding is neither technically feasible nor economically affordable. Instead on a larger scale it is key to start identifying flash-flood prone areas especially in catchments with historical flash floods. We should then focus on advocating for climate action and resilience measures, which can be anything from “hard” defences like new flood walls, through to policies and better public awareness of the risks. Only this will offer hope of a safer and more resilient future.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Ioanna Stamataki has received funding from EPSRC, The Leverhulme Trust and the British Council.</span></em></p>One village recorded 1.5 year’s rain in 18 hours.Ioanna Stamataki, Lecturer in Hydraulics and Water Engineering, University of GreenwichLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2115652023-08-21T09:29:41Z2023-08-21T09:29:41ZWhy beaver-like dams can protect communities from flooding – new research<figure><img src="https://images.theconversation.com/files/543416/original/file-20230818-25-h4mqsp.png?ixlib=rb-1.1.0&rect=0%2C0%2C1379%2C1032&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A beaver-like dam at Wilde Brook on the Corve catchment in Shropshire.</span> <span class="attribution"><span class="source">Daniel Jones</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Low cost, human-made river barriers, similar to those built by beavers, can protect communities at risk of flooding. </p>
<p>Our <a href="https://www.sciencedirect.com/science/article/pii/S0022169423006868?via%3Dihub">new research</a> has found that such natural barriers intentionally increase water levels upstream to slow down river flow. These flood barriers are made of materials like logs, branches, mud and leaves. They reduce downstream water levels by deliberately blocking the river and storing the water. They then slow down the river flow during a storm. </p>
<p>Using natural processes to temporarily store water above and below ground is called natural flood management. It essentially involves using nature as a sponge to soak up rainwater. </p>
<p>Not only does this protect communities further down the river from flooding, but it has other benefits too. It helps to <a href="https://www.science.org/doi/10.1126/sciadv.abj0988">enhance</a> habitat diversity for river insects and animals, <a href="https://onlinelibrary.wiley.com/doi/10.1002/esp.5483">trap</a> pollutants, and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169555X11006088?via%3Dihub">enhance</a> the supply of sediment to the floodplain. </p>
<p>It also adds resilience to the river during spells of dry and hot weather by preventing it from drying up entirely. That was a big issue during the summer of 2022, which was the UK’s <a href="https://www.theguardian.com/uk-news/2023/jul/27/2022-warmest-year-record-uk-met-office-extreme-heat#:%7E:text=2022%20was%20the%20warmest%20year,19%20July%20at%20Coningsby%2C%20Lincolnshire.">warmest on record</a>.</p>
<p>Until our recent research, very little data existed on how effective such river barriers are, or how such approaches might best be used. We also did not understand how these beaver-like dams operate during big storms.</p>
<h2>Slowing the flow</h2>
<p>The presence of a tree trunk or similar obstacle in a river will disrupt its flow. But the exact extent to which the water flow was slowed down by one natural barrier, let alone 50 to 100 barriers, was unknown. We also did not understand how the flow changed for different types of storms and different river settings. </p>
<p>The theoretical idea of a natural barrier is that they have a big hole at the bottom for everyday river flows, as well as holes in between the logs and branches in the upper part of the barrier where the water slowly flows through after a small storm. </p>
<p>During heavy rainfall, the water level gets higher and flows over the top of the barrier. </p>
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<img alt="A brown beaver sits in brown water with a leafy branch in its mouth" src="https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543418/original/file-20230818-29-vmwq35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Beavers are natural engineers and make dams by using their teeth to cut trees and branches.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/european-beaver-scotland-uk-113509768">Mark A. Rice/Shutterstock</a></span>
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<p>We found that the barrier’s holes can become bigger due to the changing flow of the river. In addition, during a storm, the twigs, leaves and sediment transported by the river flow can accumulate behind the barrier, causing it to grow in size. So, we needed to understand how these natural barriers evolve over time to understand the range of their effectiveness.</p>
<p>Engineers use computer models called “<a href="https://wires.onlinelibrary.wiley.com/doi/epdf/10.1002/wat2.1568">flood models</a>” which use mathematical equations to predict how different storm sizes impact on river water levels. These help us predict when a river will burst its banks, and then the location and extent of a flooded area. </p>
<p>This is important as it helps governments decide on what type of flood defence is needed to protect people from existing and future flooding. It also helps to determine where new buildings can be constructed that will be safe from flooding, and that such new builds will not make existing houses more vulnerable to floods. </p>
<h2>The Corve catchment in Shropshire</h2>
<p>We gathered data from 105 natural flood barriers on a small Shropshire river to measure their effectiveness in holding back flood waters and to understand how natural flood barriers operate during a storm. We collected water levels, velocity and flow data every 15 minutes for a two year period. </p>
<p>We also used a technique called “<a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/photogrammetry">photogrammetry</a>”. This is where data from drone photographs are used to obtain accurate measurements of the topography in areas of river covered by trees and other vegetation. </p>
<p>Our results showed that the natural flood barriers at the site could store enough water to fill at least four Olympic-sized swimming pools during significant storms such as <a href="https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-storm-centre/storm-dennis">Storm Dennis</a>, which hit the UK in February 2020. </p>
<p>This shows that natural barriers are effective in slowing down the flow of the river during periods of rainfall, storing up vast quantities of water which would otherwise rush through, causing damage to areas downstream. Instead, this force is slowly released over a period of one to two weeks. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/beavers-offer-lessons-about-managing-water-in-a-changing-climate-whether-the-challenge-is-drought-or-floods-168545">Beavers offer lessons about managing water in a changing climate, whether the challenge is drought or floods</a>
</strong>
</em>
</p>
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<p>Our research shows that natural flood management works. It is also cheaper than traditional engineering works and complements rather than replaces existing flood defences.</p>
<p>The information from our study will help natural barriers be more accurately represented in flood models, using our new observations on barrier changes over time and effectiveness during storms. </p>
<p>Society can get better value from our flood defence spending by supporting landowners to install natural solutions. This is increasingly an issue as more and more houses are <a href="https://www.independent.co.uk/news/uk/home-news/homes-flooding-building-council-lvgi-b1962122.html">being built</a> on land at risk of flooding. </p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Catherine Wilson receives funding from the EPSRC, the Environment Agency, Shropshire Council, and Merthyr Tydfil County Borough Council. She received funding from Shropshire Council and Environment Agency to conduct this work. She is a member of the Welsh Government's Flood Coastal Erosion Committee. </span></em></p><p class="fine-print"><em><span>Elizabeth Follett receives funding from the Royal Academy of Engineering. She received funding from the European Regional Development Fund through the Welsh Government Sêr Cymru program 80762-CU-241 with a contribution from Jacobs, and the European Union's Horizon 2020 research and innovation program under the Marie Skłowdowska‐Curie grant agreement WoodJam No. 745348 to conduct this work. </span></em></p><p class="fine-print"><em><span>Valentine Muhawenimana does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A new study shows that river barriers, similar to those built by beavers, can protect areas at risk of flooding by storing water upstream.Catherine Wilson, Reader in Environmental Hydraulics, Cardiff UniversityElizabeth Follett, Royal Academy of Engineering Research Fellow, University of LiverpoolValentine Muhawenimana, Postdoctoral Research Associate in Environmental Engineering, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1838202022-06-24T03:07:27Z2022-06-24T03:07:27ZOur flood predictions are getting worse as the climate changes. We have to understand how hills shape floods<figure><img src="https://images.theconversation.com/files/469932/original/file-20220621-21-sgholt.jpg?ixlib=rb-1.1.0&rect=37%2C0%2C4120%2C2454&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Protecting people from floods requires many technical professionals to make good predictions and decisions. </p>
<p>Meteorologists predict the risk of extreme rainfall. Hydrologists translate this rainfall into predictions about what the flood will be like in terms of depth, flow and speed. Engineers design roads, bridges and buildings to cope with the likely conditions, while planners ensure new development is compatible with flood risks. </p>
<p>No step in this process is easy – and most are getting harder. Climate change is worsening flooding, because a hotter atmosphere can hold more water vapour which supercharges clouds. A hotter climate provides more energy to lift wet air high into the atmosphere, where it cools, becomes liquid and forms extreme rainfall. In Australia’s north, the intensity of heavy rainfall events has already <a href="http://www.bom.gov.au/state-of-the-climate/documents/State-of-the-Climate-2020.pdf">increased by 10%</a> since 1979. </p>
<p>While it is difficult to adapt to unpredictable rainfall events, we can improve our flood predictions. We <a href="https://www.sciencedirect.com/science/article/abs/pii/S1364815222001141">focused on improving</a> a common flood prediction technique called the Rational Method. </p>
<p>While simple to use, it can also get some things very wrong – such as underestimating flood peaks by 200%. To fix this, we worked with the developers of Arc Hydro, a popular software package used by stormwater and flood planners, to <a href="https://community.esri.com/t5/water-resources-documents/arc-hydro-hillslope-delineation-and-critical/ta-p/1153634/jump-to/first-unread-message">better describe</a> how the shape of hillslopes affects floods. We hope this can help planners gain a better understanding of the true flood risks in specific areas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brisbane floods 2022" src="https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469933/original/file-20220621-15-jmwx8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The changing climate makes floods harder to predict. This photo shows Brisbane’s floods in March 2022.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Why do we need better flood predictions?</h2>
<p>It’s particularly hard to predict the risk of extreme storms – like those that drove devastating flooding in parts of New South Wales and Queensland earlier this year – because for these storms, the past is not a good guide to the future. Those floods came from a “rain bomb” which dumped 60% of south east Queensland’s normal annual rainfall in <a href="https://www.climatecouncil.org.au/wp-content/uploads/2022/03/Final_Embargoed-Copy_Flooding-A-Supercharged-Climate_Climate-Council_ILedit_220310.pdf">just three days</a>. </p>
<p>Managing flood risks is hard, given the cost of flood protection, evacuation and resilience in developed areas and challenges in restricting development in high-risk areas. In recent years, there has been intense pressure on planners in Australian cities to provide new housing stock. The land development sector also makes substantial <a href="https://publicintegrity.org.au/wp-content/uploads/2021/01/Donations-case-study-property-and-construction-industry-1.pdf">political donations</a>. Unsurprisingly, these pressures have led to development on flood-prone land. Flooding during the ongoing La Niña events has <a href="https://www.theguardian.com/australia-news/2022/mar/11/thousands-more-to-live-on-floodplain-on-sydneys-fringes-if-developments-allowed-to-proceed">paused development</a> in some areas. </p>
<p>Australia has robust guidance available to predict flood risk. The federal government’s <a href="https://arr.ga.gov.au/">Australian Rainfall and Runoff</a> guidance is world-leading. Unfortunately, to use this properly, you need to undertake high quality analysis, detailed physical modelling, and thoughtful exploration of uncertainty. This can be expensive, requiring specialised software, highly trained experts, and enough data and time. That’s why many planners in Australia and globally still turn to simpler methods of flood assessments like the Rational Method.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-flooding-is-still-so-difficult-to-predict-and-prepare-for-126866">Why flooding is still so difficult to predict and prepare for</a>
</strong>
</em>
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<h2>Simpler is not always better</h2>
<p>While appealing, simpler methods are more likely to be inaccurate. Although there are longstanding concerns about <a href="https://onlinelibrary.wiley.com/doi/10.1111/1752-1688.12949">the reliability</a>, the method remains stubbornly popular and recommended in design standards globally. Rather than scolding engineers for using the Rational Method, we aimed to improve it.</p>
<p>To maintain simplicity, the Rational Method overlooks many factors affecting how floods form. We looked at one vital factor – the shape of the landscape. When rain falls on sloping land, it flows to the bottom of valleys where stream channels form. But hillslopes aren’t “flat” like a sheet of cardboard – they curve in different ways.</p>
<p>We were worried about divergent hillslopes, which fan out from a short section of ridge to a long stretch of stream. Under these conditions, the Rational Method overestimates how long rain needs to fall to produce a worst-case flood. By overestimating how long a storm will last, the Rational Method underestimates rainfall extremes. That can lead to very significant errors, such as underestimating the flood peak <a href="https://ascelibrary.org/doi/10.1061/%28ASCE%29HY.1943-7900.0001900">by 200%</a>. </p>
<figure class="align-center ">
<img alt="Hillslope shape examples" src="https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=232&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=232&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=232&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=291&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=291&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466632/original/file-20220601-48778-2t0r5n.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=291&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Two common types of hillslopes are convergent (at left), which are narrower at the bottom, and divergent (at right), which are wider at the bottom. Our research focused on divergent hillslopes.</span>
</figcaption>
</figure>
<p>To fix this issue, we developed a mathematical theory to correct flood predictions based on the shape of the hillslope. We tested our new theory using experiments run on carefully engineered model hillslopes and found it <a href="https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/hyp.13879">worked as expected</a>. </p>
<figure class="align-center ">
<img alt="Scale model hillslope experiment." src="https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465801/original/file-20220527-17-t4qkt.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We used tiny nozzles to spray water onto a sand-coated foam board to test flood generation theory.</span>
<span class="attribution"><span class="source">Dana A Lapides</span></span>
</figcaption>
</figure>
<h2>From theory to practice</h2>
<p>Sadly, mathematical theories aren’t usually popular outside academic circles. To share our new approach with users, we worked with Esri, the developer of the globally popular <a href="https://www.esri.com/en-us/industries/water-resources/arc-hydro">Arc Hydro GIS package</a> used by stormwater and flood planners. </p>
<p>Together, we built <a href="https://community.esri.com/t5/water-resources-documents/arc-hydro-hillslope-delineation-and-critical/ta-p/1153634/jump-to/first-unread-message">new tools</a> for the package which map hillslopes, describe the hillslope shape mathematically, and use our new theory to improve predictions produced by the Rational Method. </p>
<p>So does it work? When we applied our tool to test watersheds in California and Arizona, we found about 40% of the hillslopes were divergent – wider at the bottom than the top. For these areas, using our new methods would improve flood predictions by up to 270%. </p>
<p>Floods are a difficult challenge for societies to deal with around the world. That’s because coping with floods requires us to make long-term decisions about where we live, how we live, and what we build in the face of a rapidly changing climate. </p>
<p>To fully address these problems is an international, multidisciplinary task for scientists, engineers, planners, policymakers and decision makers. We hope our improvement to the Rational Method will be a small, but useful, part of this great endeavour.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-in-1-000-years-old-flood-probabilities-no-longer-hold-water-178524">One in 1,000 years? Old flood probabilities no longer hold water</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/183820/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Thompson receives funding from the Australian Research Council, the Western Australian Department of Water and Environmental Regulation, and the Water Corporation (Western Australia). </span></em></p><p class="fine-print"><em><span>Anneliese Sytsma receives funding from The Colorado School of Mines, National Science Foundation's Engineering Research Center for Reinventing the Nation's Urban Water Infrastructure (ReNUWIt) (EEC-1028968), and the Gledden Foundation at the University of Western Australia's Institute for Advanced Studies.</span></em></p><p class="fine-print"><em><span>Dana Ariel Lapides receives funding from Simon Fraser University and the United States Department of Agriculture (USDA) Forest Service Southwest Pacific Research Station administered by the Oak Ridge Institute for Science and Education (ORISE). </span></em></p><p class="fine-print"><em><span>Mary H. Nichols receives funding from the United States Department of Agriculture - Agricultural Research Service 9USDA-ARS) at the Southwest Watershed Research Center.
</span></em></p>A warmer atmosphere can hold more water – and that makes floods harder to predict. To help, we improved one common tool used to predict floods.Sally Thompson, Associate professor, The University of Western AustraliaAnneliese Sytsma, Postdoctoral fellow, Colorado School of MinesDana Ariel Lapides, Postdoctoral Research Fellow, Simon Fraser UniversityMary H. Nichols, Research scientist, USDA-ARS Southwest Watershed Research CenterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1646482021-07-16T18:54:08Z2021-07-16T18:54:08ZReport from Europe’s flood zone: researcher calls out early warning system gridlock amid shocking loss of life<p>It was close to midnight when I received a phone call from my sister telling me that our parent’s house was under water. Neither she nor they really knew what to do next. They were in a state of shock amid an ongoing emergency.</p>
<p>I drove from my house in Luxembourg City to my hometown on the only road that was still passable – and even that didn’t stay that way for long. The streets were empty and I passed no one. My parents had already called the fire service for help, but they were advised that they could not come in the next few hours.</p>
<p>I arrived to find the lower level of my childhood home submerged. There we were, together as a family, holding torches, knee deep in the water, trying to get as much of it out, one bucket at a time.</p>
<p>My parent’s experiences will largely be counted in material loss. But water damage does not capture what they and many others went through that night. During the pandemic, people have related differently to their homes. Declared a place of refuge from the invisible threat of the virus, home is supposed to be one place you can feel safe. This is especially true for the most vulnerable and the elderly. I was heartbroken to see my parent’s sense of safety swept away in a matter of minutes.</p>
<figure class="align-center ">
<img alt="Two people stand on a staircase beset by rising water." src="https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411723/original/file-20210716-21-4advzu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The author’s parent’s house.</span>
<span class="attribution"><span class="source">Jeff Da Costa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In my PhD research, I study how we can effectively adapt to the consequences of increasing severe weather events under climate change and what can be done to prepare for them and mitigate their impact. One area I’m interested in is early warning systems, or the lack thereof, during extreme weather events, such as the recent floods in western Europe.</p>
<p>While the climate is certainly a complex system that is difficult to predict with any certainty, the unfolding catastrophe is a sad reminder of just how inadequate early warning systems can be.</p>
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<h2>Gridlocked early warning systems</h2>
<p>The European Flood Awareness System (EFAS) issued a <a href="https://www.politico.eu/article/germany-floods-dozens-dead-despite-early-warnings/">flood notification</a> at the beginning of the week, announcing that there would be extreme rainfall and the risk of floods mid-week in the most severely hit regions (western Germany, Luxembourg, eastern Belgium and southern Netherlands).</p>
<p>This information was passed to a variety of national authorities, which can differ depending on the member countries. In Luxembourg it’s the fire and rescue service. These bodies are in charge of transmitting the message to relevant local authorities.</p>
<p>It is within each country’s laws and regulations to determine which authority has the power to issue warnings to their citizens.</p>
<figure class="align-center ">
<img alt="A flooded semi-rural landscape." src="https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411724/original/file-20210716-25-igsa6l.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The author’s hometown on July 18 2021.</span>
<span class="attribution"><span class="source">RSS-HYDRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This delegation of responsibility meant that the southern Dutch province of Limburg <a href="https://www.iamexpat.nl/expat-info/dutch-expat-news/flooding-limburg-continues-towns-and-cities-evacuated">issued evacuation warnings</a> on the Wednesday afternoon, well before the flood hit the region, while in neighbouring Germany, the state of <a href="https://www.bbc.com/pidgin/tori-57859887">Rhineland-palatinate</a> only started evacuating people when it was too late.</p>
<p>Evacuating people when they are already knee deep in water is not a successful way to mitigate against disaster and it does not bode well for the ability of countries to adapt to these events in future. Early warning systems cannot be successful if used in this manner.</p>
<p>EFAS did send out early notifications, sometimes in addition to information from national services. But the bodies receiving this information were specific to each country. As a result, the responsibility of implementing any actions on the ground based on a flood warning is taken at a political level.</p>
<p>So why are there no coordinated warning systems in place for all affected areas, regardless of borders and local government? The system is fundamentally flawed. While the EFAS is highly effective in detecting threats, the different ways countries delegate responsibility for warning their citizens creates a gridlock along the chain of transmission. Ordinary people pay the price, sometimes with their lives.</p>
<p>There are systems in place to protect us. Weather models have high enough resolution to warn us, often in enough time. But somewhere along that line from meteorologists to the public, there is a gap. That is where I will be focusing my attention in my research. After all, if we cannot manage the present, what does that say about our plans for the future?</p><img src="https://counter.theconversation.com/content/164648/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Da Costa works with RSS Hydro as part of an industrial fellowship grant.</span></em></p>Catastrophic floods in north-western Europe have shown how badly early warning systems can fail.Jeff Da Costa, PhD researcher in Environmental Science at the University of Reading & PhD Fellow at RSS-Hydro, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1268482019-11-15T16:01:20Z2019-11-15T16:01:20ZFlood survivors should be given proper support – instead they’re told to get ‘resilient’<p>After <a href="https://www.bbc.co.uk/news/uk-england-50372839">severe flooding in the North of England</a>, many affected residents have been left feeling <a href="https://www.theguardian.com/environment/2019/nov/09/flood-waters-receding-but-anger-rises-in-weary-doncaster">let down and left behind</a> by the systems in place to protect them. <a href="https://link.springer.com/article/10.1007/s10113-017-1216-3">Our research suggests</a> that they, and many other communities affected by flooding in the past, have good reason to feel this way.</p>
<p>Often, the effects of flooding are not fair – and government policy isn’t helping. Current methods of modelling, managing and protecting against flood risk are socially blind, and end up disadvantaging the people and places that are most vulnerable.</p>
<p>In recent years, flood management policy across the world has <a href="https://environmentagency.blog.gov.uk/2017/06/27/flood-risk-management-10-years-on-a-journey-of-high-and-low-tech-improvements/">focused investment on technology</a> to better assess which areas are at risk of flooding, and what the damage could be. This technical expertise can then be used to inform vulnerable people, guide development, and determine priority areas for flood defences.</p>
<p>Undoubtedly, innovation in flood risk assessments over the last two decades has aided decision-making for central government agencies and local authorities. We have a much better, if still far from perfect, understanding of the movement of water through catchments, urban drainage systems, streets and buildings.</p>
<p>But this approach has limitations. For a start, flood maps tend to be static snapshots that are only periodically updated. In reality, risk can change quickly. As the climate crisis <a href="https://theconversation.com/three-times-more-people-at-risk-from-yearly-coastal-flooding-than-previously-thought-new-research-125920">increases the frequency and severity of flooding</a>, and urbanisation reduces the land’s capacity to absorb water, people may be surprised to learn that houses they bought many years ago are now at risk – not because they moved to a flood-prone area, but because the flood zone moved to them.</p>
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Read more:
<a href="https://theconversation.com/three-times-more-people-at-risk-from-yearly-coastal-flooding-than-previously-thought-new-research-125920">Three times more people at risk from yearly coastal flooding than previously thought – new research</a>
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<p>More importantly, these technical models typically treat flood-prone areas as uniform entities that are simplistically labelled as at high, medium, or low risk. In turn, government policy across Europe and beyond increasingly expects people at risk to assume more responsibility for managing it, usually referring to this as becoming <a href="https://environmentagency.blog.gov.uk/2016/11/11/make-your-home-more-flood-resilient/">resilient</a>. For example, the UK government encourages the public to check their postcode on <a href="https://flood-warning-information.service.gov.uk/long-term-flood-risk/map">simplified versions of flood maps</a>, to inform choices on insurance or house purchases, increase their awareness of risk, and be prepared if in a higher-risk area.</p>
<p>But people have very different capacities to make use of this information. For example, those with lower incomes may be less able to protect, repair or <a href="https://www.jrf.org.uk/report/social-justice-and-future-flood-insurance">insure their properties</a>, meaning they feel the effects of flooding much more acutely.</p>
<p>Some people are also more vulnerable than others in ways that may not be immediately obvious. Extreme weather events are likely to have a greater effect on older people and those with health problems. Those with limited mobility are <a href="https://www.ageuk.org.uk/globalassets/age-uk/documents/reports-and-publications/reports-and-briefings/active-communities/rb_feb16_older_people_and_power_loss_floods_and_storms.pdf">less able to evacuate</a> from a flooded area or move possessions away in expectation of a flood.</p>
<p>More broadly, the varying economic health of areas entrenches inequality in <a href="https://www.jrf.org.uk/report/targeting-flood-investment-and-policy-minimise-flood-disadvantage">vulnerability to flooding</a>. Put simply, people from more deprived areas that are prone to flooding may not only be more vulnerable to its effects, but are often less able to lobby for flood defences or media attention than those in wealthier areas. They also have fewer means to leave flood prone areas for a safer place to live.</p>
<p>The often overlooked yet troubling irony is that globally it is those who have contributed least to the causes of flooding and have the least capacity to adapt that are most at risk. And of course, flooding rarely happens just once in an area – people and places can be trapped in <a href="https://theconversation.com/hurricanes-flood-insurance-and-the-dangers-of-business-as-usual-83602">cycles of flooding</a>, further exacerbating inequality and disadvantage.</p>
<h2>‘Just’ defences</h2>
<p>Decisions about where to invest in flood defences are <a href="https://theconversation.com/flood-defences-simply-arent-good-enough-heres-what-needs-to-be-done-126781">also problematic</a>. They are usually based on simple cost-benefit analyses, which means that assessments of how many people might be protected and the value of protected assets rule decision-making processes.</p>
<p>Many analyses have some degree of <a href="https://www.gov.uk/government/publications/flood-and-coastal-erosion-risk-management-appraisal-guidance">social weighting</a> to ensure that wealthy areas with higher house prices or areas with larger populations do not monopolise finite budgets. But only rarely are more fine-grained social circumstances, such as people’s ability to escape from rising water and their capacity to deal with the consequences of a flood, integrated into decision-making.</p>
<p>In response, flood risk management researchers and professionals increasingly argue for more engagement and collaboration with those at <a href="https://nationalfloodforum.org.uk/working-together/communities/what-is-a-flood-action-group/">risk</a>. But even here, there is a risk that the simple provision of more opportunities to participate could favour those with resources, expertise and time – the very same people who are arguably already well represented in the processes of public decision-making.</p>
<p>That is not to criticise vocal and well organised community participation. Such participation is essential and must be supported. But to truly realise social and environmental justice and prevent communities suffering in silence, targeted outreach is needed. This could include recruiting independent support workers who can be community advocates for vulnerable neighbourhoods, and helping establish local <a href="https://thefloodhub.co.uk/community/">flood action groups</a> to liaise between authorities and the wider <a href="https://eyeoncalderdale.com/">public</a>.</p>
<h2>Fairer flooding</h2>
<p>There are ways to make flooding fairer. Public authorities sit on a vast wealth of social, economic and demographic data that should be fully integrated with flood risk management decision-making, and regularly updated. The mapping tools to overlay these data with flood maps already <a href="https://www.climatejust.org.uk/">exist</a>, but there is concern that these are not being widely used.</p>
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<a href="https://theconversation.com/why-flooding-is-still-so-difficult-to-predict-and-prepare-for-126866">Why flooding is still so difficult to predict and prepare for</a>
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<p>Flood risk managers and emergency first responders should also do more to understand these nuances. They could, for example, expand recent efforts to help communities develop their own <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/292939/LIT_5286_b9ff43.pdf">specific flood response plans</a>, use their local knowledge to identify the most vulnerable people, and determine ahead of time how they can be supported when flood warnings are issued.</p>
<p>Finally, we need to recognise that fairness in flooding is linked to broader economic and social conditions. Austerity politics and funding cuts to local services can severely compromise people’s ability to deal with flooding.</p>
<p>In the UK, spending on flood defences has <a href="https://news.sky.com/story/general-election-does-flood-defence-spending-unfairly-favour-the-south-east-11859986">fallen well shy of the pre-austerity trend</a> – and this is sure to have impacted residents in the North of England. Our ongoing work shows that many communities affected by flooding feel ignored long before rising waters destroy their homes, businesses and neighbourhoods.</p>
<p>Those most vulnerable to flooding must be given the resources to respond to it, rather than being told that it’s their responsibility to get resilient. This support is not only needed before and during flooding events, but also for the longer-term effects that are often only apparent weeks and months after waters have subsided. Just as our assessment of flood risk is getting more sophisticated, so must our management of it.</p>
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<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1126848">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/126848/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Current policy to manage and protect people from flooding disadvantages those who are most vulnerable.Paul O'Hare, Lecturer in Human Geography and Urban Development, Manchester Metropolitan UniversityIain White, Professor of Environmental Planning, University of WaikatoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1268662019-11-13T13:14:17Z2019-11-13T13:14:17ZWhy flooding is still so difficult to predict and prepare for<figure><img src="https://images.theconversation.com/files/301529/original/file-20191113-77326-150d4yj.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4546%2C3055&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/edinburgh-uk-november-3-2019-people-1551585830?src=5331378b-2b01-4954-a526-a2b0f4d5610b-1-41">Olesea vetrila/Shutterstock</a></span></figcaption></figure><p>Before you read this story, take a minute to stop and look around you. Now imagine your surroundings under two feet of <a href="https://theconversation.com/why-people-in-a-flooded-british-town-were-told-to-stop-flushing-the-toilet-119115">dirty, sewage-filled water</a>. If you’re at home, everything is trashed. Never mind your car, your furniture or washing machine. They will be ruined, but those things can be replaced. Think of your wedding album, soaked and spoiled. The music box your grandmother gave you, full of stinking mud.</p>
<p>That is the reality of being flooded. And sadly, it’s a reality that many people in the UK – in Yorkshire and Lincolnshire – have faced in the recent floods. Tragically, floodwater can also <a href="https://www.bbc.co.uk/news/uk-england-derbyshire-50360306">be life-threatening</a>.</p>
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Read more:
<a href="https://theconversation.com/flood-defences-simply-arent-good-enough-heres-what-needs-to-be-done-126781">Flood defences simply aren't good enough – here’s what needs to be done</a>
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<p>Given the huge costs to people and property when it floods, it’s a reasonable question to ask why, in one of the richest countries in the world, more cannot be done to prevent flooding. And if not prevent it, to know more precisely when and where it will hit.</p>
<p>As a hydrologist and a flood and hazard forecaster, I spend my life doing just that. And despite the work of some of the brightest scientists, the world’s most advanced supercomputers and the commitment of hardworking people on the ground, floods are just difficult beasts to pin down. And if you’ve ever thought that your home could never be affected, you should know that floods can happen almost anywhere, at any time.</p>
<h2>Modelling chaos</h2>
<p>Some of the most wonderful aspects of the UK – the changeable weather and spectacular landscape – are also what makes the country so susceptible to flooding. When beautiful river valleys and low-lying plains – as well as cities and urban areas – are inundated with persistent rain, sudden downpours or high tides with storms, flooding can quickly follow. Especially if there is an unexpected fault in the infrastructure designed to hold back water or prevent flooding, as was seen at <a href="https://theconversation.com/whaley-bridge-dam-collapse-is-a-wake-up-call-concrete-infrastructure-will-not-last-forever-without-care-121423">Whaley Bridge in Yorkshire in August 2019</a>.</p>
<p>In Doncaster in early November 2019, only a slight variation in a fairly typical weather system was enough to cause flooding. Cold and warm air masses regularly press against each other close to North America, creating an Atlantic storm factory. These weather systems are often fired towards Europe too by the strength and direction of the jet stream. Damp ground in the north of England is also par for the course. But add one heavy downpour, caused by a rotating weather front getting “stuck” over one area – and you have a flood.</p>
<p>Weather predictions have come a long way in the past few decades – today’s three-day forecast is as accurate as a 24-hour forecast was in the 1990s. <a href="https://theconversation.com/why-the-weather-forecast-will-always-be-a-bit-wrong-101547">But they are never perfect</a>.</p>
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Read more:
<a href="https://theconversation.com/rivers-are-changing-all-the-time-and-it-affects-their-capacity-to-contain-floods-126659">Rivers are changing all the time, and it affects their capacity to contain floods</a>
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<p>Multiply all the uncertainty within the weather forecast with all the complexity of modelling the path of water travelling through the landscape – both above and below ground – then you start to get an idea of the difficulties forecasters face. We have to take account of all the different routes through the landscape that a single raindrop might take. There are billions upon billions of different possibilities. It requires lots of assumptions.</p>
<p>So much for looking into the future. What about learning from the past?</p>
<p>Many people in flood-hit areas have said that the floods are unprecedented. Older residents have said they have never seen anything like it. But we must remember our landscape is thousands – even millions – of years old. We need to think about much longer timescales than single human lifespans. And of course on top of this, the landscape and climate are changing – so even the best historic data don’t provide a good proxy of the future.</p>
<p>Fishlake may not have flooded in recent years, but it is right on the floodplain of the River Don. Its watery name is <a href="https://www.bbc.co.uk/news/uk-england-50372839">probably no coincidence</a>. Neither is that of Meadowhall, the shopping centre in Sheffield, more than likely built on a flood meadow. On November 8, <a href="https://www.bbc.co.uk/news/uk-50341846">it was marooned</a>. But people tend to like living by the river – and they don’t associate a beautiful riverside development with dirty water and destroyed wedding photos.</p>
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<p>Flooding is hard to predict and prepare for. But floods happen. They always have – and we know that as the global climate warms due to human activity we are likely to <a href="https://advances.sciencemag.org/content/5/9/eaaw5531">see more of some types of flood</a> in Britain. It’s hard to convince people who don’t know they are at risk that they should prepare for the worst.</p>
<p>This is where the government must step in. To better prepare for floods, we need difficult, expensive, but rational decision-making on flood defences. That would mean seriously considering the risk of building homes and businesses in the floodplain, and planning away from these areas as much as possible. If there is no other option, then the flood-proof design standards must be substantially higher. Developers must also be held to account for ensuring these standards are met and householders must be made fully aware of the risks.</p>
<p>Forecasts and communications of flood risks can always be improved, and my colleagues and I will be working hard on it for years to come. But residents, farmers and businesses can’t be expected to face off the problem of floods on their own.</p><img src="https://counter.theconversation.com/content/126866/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hannah Cloke advises the Environment Agency on flood risk and flood forecasting. She works with local flood groups and advises local and national government on flood emergencies. Her flood research is funded by the Natural Environment Research Council, the European Commission's Horizon 2020 programme.</span></em></p>Today’s three-day weather forecast is as accurate as a 24-hour forecast in the 1990s. But floods are still particularly tricky to pin down.Hannah Cloke, Professor of Hydrology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1266592019-11-11T17:03:12Z2019-11-11T17:03:12ZRivers are changing all the time, and it affects their capacity to contain floods<figure><img src="https://images.theconversation.com/files/301112/original/file-20191111-194656-1b0knrl.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Houses alongside the Saigon river in Vietnam.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/fAYHQEopGPA">Tony La Hoang/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><a href="https://www.bbc.co.uk/news/uk-england-50372839">The rainfall</a> that has inundated the North of England is the <a href="https://inews.co.uk/news/environment/uk-flooding-news-latest-worst-europe-climate-change-494940">latest in a long line</a> of flood events that are becoming <a href="https://theconversation.com/heatwaves-and-flash-floods-yes-this-is-britains-new-normal-121351">the country’s new normal</a>. Indeed, across the world, flooding is expected to become <a href="https://www.ipcc.ch/sr15/">more frequent and more extreme</a> as the planet heats up.</p>
<p>Building robust flood defences and modelling vulnerable areas is crucial if we are to avoid loss of life and livelihoods from these devastating weather events. But <a href="https://www.nature.com/articles/s41598-019-48782-1">our new research</a> reveals that the capacity of rivers to keep water flowing within their banks can change quickly – and in failing to acknowledge this, some flood models and defences may be under-equipped to deal with the consequences when they do.</p>
<p>Many assume that flooding is due to <a href="https://www.int-res.com/articles/cr_oa/c047p123.pdf">heavy rainfall</a>. This is true, but only part of the explanation. Floods also occur when the amount of water running off the land exceeds the capacity of rivers to carry that flow – as was the case when the River Don breached flood defences in the Sheffield area recently. So, floods are partly caused by the amount of rain falling, partly by the moisture that is already in the ground, and partly <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL062482">by the capacity of rivers to contain water</a> within their channels.</p>
<p>This means that if the capacities of river channels change, then two identical rainfall events falling on similarly wet ground can cause flooding of very different severity.</p>
<p>Most rivers are forever changing. They are shaped by the sediments and water they carry. <a href="https://www.sciencedirect.com/science/article/pii/S0169555X06002509">Humans have modified</a> most of the world’s rivers in some way. In some cases this is through direct influence, such as dam construction or river engineering. Other influences are indirect – building on nearby land reduces the capacity of ground to absorb water, agriculture draws water from rivers, and deforestation leaves more water to flow elsewhere.</p>
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<span class="caption">After the River Don burst its banks in places, multiple roads in urban centres such as Rotherham flooded.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rotherham-uk-november-8-2019-river-1553828930?studio=1">DnG Photography/Shutterstock</a></span>
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<p>Rivers respond to changes in climate as well. During drier periods, <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1002/wat2.1085">less water flows through river systems</a>. This means that there is often less energy to move the sediments at their beds, so riverbed levels may progressively rise, decreasing the capacity of the river. Abundant plant growth within the channel can also reduce a river channel’s capacity by <a href="https://doi.org/10.1061/(ASCE)0733-9429(1999)125:5(443)">slowing the flow</a>.</p>
<p>But it is not always easy to predict how rivers will change. Extreme shifts in channel shape and capacity can occur very rapidly. After a recent flash flood in Spain, one river rose almost <a href="https://www.nature.com/articles/s41598-019-38537-3">a metre</a> as huge volumes of sediment from upstream were displaced and dumped further along. In tropical river systems, which tend to carry more sediment than temperate rivers, these changes can be <a href="https://www.sciencedirect.com/science/article/pii/S0169555X19300212">several metres</a>.</p>
<h2>Uncertain risk</h2>
<p>Unfortunately, such changes are typically ignored by flood engineers and modellers, who generally treat the channel as a fixed feature. If rivers actually change their capacity in space and time, then estimates of flood probability may be incorrect, putting people and property at risk.</p>
<p>Motivated by these concerns, we investigated the pace at which channel changes occur, and to what extent these alterations might be driven by climate. We began with a simple conceptual model: climate controls rainfall, rainfall affects river flow, and river flow shapes channel capacity. </p>
<p>Direct observations of this link were lacking in river systems over short timescales. So, we took 10,000 measurements of the capacity of 67 rivers in the US, covering a period of nearly 70 years. We also gathered rainfall and river flow data, to assess how climatic changes affected the capacity of the rivers.</p>
<p><a href="https://www.nature.com/articles/s41598-019-48782-1">We discovered</a> that temporary shifts in river capacity, lasting years to decades, were far more frequent than had previously been assumed. Overall, river capacity tends to increase during periods that are wetter than average due to greater erosion of river channels, and decrease in drier periods.</p>
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<span class="caption">The flood-prone Ganges river is a lifeline to millions who live along its course.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ganges-river-flood-water-premises-near-1516489166">Joachim Bago/Shutterstock</a></span>
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<p>We also found that multi-year climate cycles that affect regional precipitation patterns – such as the El Niño Southern Oscillation – can cause channel capacity to expand and contract too, perhaps on a global scale. Armed with this knowledge, we may eventually be able to predict how the capacity of rivers changes, and hence better understand flood risk.</p>
<p>In temperate regions such as the UK, where rivers tend to be vegetated, heavily engineered and relatively stable, delicate changes in channel capacity are hard to detect and unlikely to be life threatening. However, in river systems that carry high volumes of sediment, or in parts of the world where rainfall varies considerably during the year, sudden reductions in river capacity may dramatically increase flood risk for nearby settlements. For example, the <a href="https://www.sciencedirect.com/science/article/pii/S0037073812001510">Ganges-Brahmaputra</a> river in India and Bangladesh falls under this category. Its capacity is already changing, and its floodplains are some of most densely populated in the world.</p>
<p>Unfortunately, we still have very poor understanding of the nature and causes of channel capacity changes in most regions – and it is the most at-risk places that tend to have the least data. To better understand what’s happening, we need to use satellite imagery to monitor how fast rivers are responding to changes in the climate. What we can’t yet do though is monitor river adjustment in real time. Developing technologies that do this would greatly improve our understanding of how changes in river shape and capacity affect flood risk across the world. </p>
<p>Until this information becomes apparent, flood models and defence structures should build this uncertain risk into their designs. Doing so could make all the difference for those living in vulnerable areas.</p>
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<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1126659">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/126659/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Slater receives funding from the Natural Environment Research Council (NERC). She is affiliated with the British Society for Geomorphology (BSG), American Geophysical Union (AGU) and European Geosciences Union (EGU).</span></em></p><p class="fine-print"><em><span>Abdou Khouakhi and Robert Wilby do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In failing to acknowledge that the capacity of rivers can change quickly, some flood models and defences may not be equipped to deal with the consequences when they do.Louise Slater, Associate Professor in Physical Geography, University of OxfordAbdou Khouakhi, Research Associate, Climate and Weather Data Analysis, Loughborough UniversityRobert Wilby, Professor of Hydroclimatic Modelling, Loughborough UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1242892019-10-23T02:49:48Z2019-10-23T02:49:48ZWater may soon lap at the door, but still some homeowners don’t want to rock the boat<figure><img src="https://images.theconversation.com/files/298079/original/file-20191022-28088-1piro4x.jpg?ixlib=rb-1.1.0&rect=21%2C0%2C4742%2C3171&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Storm-damaged beachfront homes along Pittwater Road at Collaroy on the northern beaches of Sydney in June 2016.</span> <span class="attribution"><span class="source">Dean Lewins/AAP</span></span></figcaption></figure><p>It is becoming increasingly possible that sea-level rise of a metre or more will occur this century. You might expect this threat to preoccupy coastal homeowners. But many deny the need to act, for fear their property values will fall.</p>
<p>This particular brand of climate denial presents a conundrum for governments and local councils, which must plan urgently for climate change. The very act of officials identifying homes exposed to sea-level rise can be vehemently opposed by the owners, let alone policies to deal with it.</p>
<p>This is an urgent problem. As long as we keep failing to reduce global carbon emissions, adapting to the inevitable changes in our climate is vital. But winning cooperation from coastal property owners requires more than just talking about the science.</p>
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<img alt="" src="https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298082/original/file-20191022-28129-1rhmit1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A car covered in sand near Bondi Beach, Sydney after heavy storms in 2015.</span>
<span class="attribution"><span class="source">David Moir/AAP</span></span>
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<h2>A tide of irrefutable facts</h2>
<p>An Intergovernmental Panel on Climate Change report released this month warned <a href="https://theconversation.com/ipcc-report-paints-catastrophic-picture-of-melting-ice-and-rising-sea-levels-and-reality-may-be-even-worse-124193">sea levels are rising faster</a> than we thought. This will lead to more flooding, storm surges and inundation than previously modelled.</p>
<p>In Australia, <a href="https://www.abs.gov.au/Ausstats/abs@.nsf/Previousproducts/1301.0Feature%20Article32004">85% of people live within 50km of the coast</a>. In 2009, a <a href="https://www.environment.gov.au/climate-change/adaptation/publications/climate-change-risks-australias-coasts">federal assessment</a> estimated that up to 247,600 Australian homes were at risk of inundation under a 1.1m sea-level rise scenario.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-seas-threaten-australias-major-airports-and-it-may-be-happening-faster-than-we-think-115374">Rising seas threaten Australia's major airports – and it may be happening faster than we think</a>
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<p>Authorities must manage this threat, which might include limiting development, protecting properties, or planning a retreat from some areas.</p>
<p>Yet <a href="https://linkinghub.elsevier.com/retrieve/pii/S0959378019301979">our research shows</a> that getting community support for such measures can be contentious and time-consuming.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298081/original/file-20191022-28125-1513sch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Waterfront properties in Point Piper, Sydney. Some 85% of Australians live near the coast.</span>
<span class="attribution"><span class="source">JOEL CARRETT/AAP</span></span>
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<h2>Property values are king</h2>
<p>We researched Lake Macquarie in New South Wales, a council area of about 200,000 residents. Lake Macquarie City Council is a <a href="https://www.lakesmail.com.au/story/4640904/council-awarded-for-winning-residents-over-on-sea-level-rise-plan/">recognised leader</a> in climate adaptation policy. </p>
<p>Lake Macquarie is a large coastal estuary vulnerable to sea-level rise. It has been identified as <a href="https://www.environment.gov.au/system/files/resources/fa553e97-2ead-47bb-ac80-c12adffea944/files/cc-risks-full-report.pdf">one of six council areas in Australia</a> at highest risk of inundation. Up to 6,800 buildings in the area – about 10% – could be at risk from sea-level rise and storm surges this century.</p>
<p>In response, the council limited development in the most vulnerable areas and in 2012 began community consultation. This included working with residents to develop an <a href="https://shape.lakemac.com.au/2116/documents/34441">adaptation plan</a>, released in 2016. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-landmark-report-confirms-australia-is-girt-by-hotter-higher-seas-but-theres-still-time-to-act-124096">A landmark report confirms Australia is girt by hotter, higher seas. But there's still time to act</a>
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<p>In 2017 and 2018, we interviewed current and former councillors and council staff, local businesspeople and residents about the consultation process.</p>
<p>We found there was initially strong resistance to the council’s policy attempts. Community members expressed concern that acknowledging the need to adapt to sea-level rise would reduce property prices and <a href="https://www.abc.net.au/news/2019-10-23/the-suburbs-facing-rising-insurance-costs-from-climate-risk/11624108">increase home insurance costs</a>.</p>
<p>The potential worst-case scenario, being required to abandon one’s home, was strongly resisted by the community.</p>
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<img alt="" src="https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298080/original/file-20191022-120690-whv98v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Heavy machinery moves onto Palm Beach on the Gold Coast to repair cliffs carved out of the front yards of beachfront homes.</span>
<span class="attribution"><span class="source">Tony Bartlett/AAP</span></span>
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<p>Such community opposition is common across Australia. The Queensland property industry <a href="https://www.themonthly.com.au/issue/2019/october/1569374459/bronwyn-adcock/rising-tide">lobbied against state requirements</a> that would have barred new development until climate adaptation plans were in place. At Lakes Entrance in Victoria, <a href="https://minerva-access.unimelb.edu.au/bitstream/handle/11343/39609/ARCL%20Gippsland%20Final%20Report%20.pdf?sequence">coastal residents have complained</a> that adaptation measures are “taking away people’s money … because they’re going to suffer financial loss”.</p>
<h2>The problem of climate denialism</h2>
<p>In 2012 when community consultation began, property developer Jeff McCloy <a href="https://www.smh.com.au/environment/climate-change/developer-may-sue-to-trigger-rethink-on-sea-level-rises-20120305-1uecc.html">told the Sydney Morning Herald</a> he was considering suing the council over its policies, describing concern over sea-level rise as “unjustified, worldwide idiocy”.</p>
<p>People <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/wcc.276">have a tendency</a> to want to see or feel the impacts of climate change before they agree to actions they see as conflicting with their priorities. </p>
<p>Property owners who live near oceans or lakes <a href="https://www.tandfonline.com/doi/full/10.1080/00045608.2014.988101">may not have observed</a> rising sea levels or other climate change effects, and sometimes hesitate to believe it will be a future problem, even if flood map modelling shows otherwise.</p>
<p>The proliferation of climate scepticism in public discourse provides ready-made arguments to which some property owners, fearful of climate change impacts, can attach themselves.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-sea-level-rise-could-displace-millions-of-people-within-two-generations-116753">Climate change: sea level rise could displace millions of people within two generations</a>
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<p>We found that these broader debates around climate change impeded Lake Macquarie council’s ability to reach agreement with residents. Those opposing the policy arranged for prominent climate sceptics to speak at public meetings, and published anti-science opinion pieces in the local newspaper.</p>
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<img alt="" src="https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298219/original/file-20191023-149585-10303qk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A yacht washed up on a beach at Little Manly Cove in Sydney in 2012 after wild storms.</span>
<span class="attribution"><span class="source">AAP/Mick Tsikas</span></span>
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</figure>
<h2>Where to now?</h2>
<p>The Lake Macquarie experience shows intensive, long-term, early efforts at community engagement can overcome some community opposition to climate adaptation. After four years of consultation, the council reached agreement with residents in two areas that affected land would be filled in over time, and there would be no forced retreat from homes.</p>
<p>The council is continuing to plan, with community involvement. It is <a href="https://pdfs.semanticscholar.org/6f51/4cc5f232e5ad89b72d26a656e20a6b43f98f.pdf">developing suburb-specific adaptation plans</a> designed so residents understand the science and embrace the solutions – including the chance to identify adaptation options themselves. </p>
<p>But across Australia, much work remains. As global carbon emissions continue to rise and the window to act closes, it is crucial that councils, governments and communities plan for whatever the future holds. This includes implementing adaptation plans that get property owners on board.</p><img src="https://counter.theconversation.com/content/124289/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Wright receives funding from Australian Research Council. </span></em></p><p class="fine-print"><em><span>Daniel Nyberg receives funding from Australian Research Council.</span></em></p><p class="fine-print"><em><span>Vanessa Bowden does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A particular brand of climate denial among coastal property owners presents a conundrum for councils and governments trying to plan for sea-level rise.Vanessa Bowden, Postdoctoral research fellow, University of NewcastleChristopher Wright, Professor of Organisational Studies, University of SydneyDaniel Nyberg, Professor of Management, Newcastle Business School, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/831872017-09-07T16:16:53Z2017-09-07T16:16:53ZHow flood insurance works: 6 questions answered<p><em>Editor’s note: <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/08/31/harvey-is-a-1000-year-flood-event-unprecedented-in-scale/">Hurricane Harvey</a> dumped up to 50 inches of rain on parts of Texas and Louisiana last month. Meanwhile, Hurricane Irma is bearing down on Florida, which will also likely cause substantial flooding. Homeowners generally rely on insurance provided by the federal government to cover the costs of rebuilding their lives after a flood. We asked an insurance expert to explain the government program and its challenges.</em></p>
<h2>1. What is flood insurance?</h2>
<p>Homeowners’ insurance does not cover damage to a home caused by flooding. A homeowner must have a separate policy to cover flood-related losses, defined as water traveling along or under the ground.</p>
<p>Most such policies are underwritten by the <a href="https://www.fema.gov/national-flood-insurance-program">National Flood Insurance Program</a>, which is part of the Federal Emergency Management Agency. The National Flood Insurance Program was established in 1968 to address the lack of availability of flood insurance in the private market and reduce the demand for federal disaster assistance for uninsured flood losses. Another purpose was to integrate flood insurance with floodplain management, which includes such things as adopting and enforcing stricter building codes, retaining or restoring wetlands to absorb floodwaters and requiring or encouraging homeowners to make their homes more flood-resistant. </p>
<p>The National Flood Insurance Program’s activities are funded largely by the premiums and fees paid by its policyholders, supplemented by a small amount of general funds to help pay for flood risk mapping. Because the National Flood Insurance Program serves the public interest, some believe that more of its funding should be borne by taxpayers.</p>
<p>Homeowners can purchase a federal flood policy directly from the National Flood Insurance Program or through a private insurer. Separately, some private insurers sell their own flood policies on a limited basis for properties that are overcharged by the National Flood Insurance Program.</p>
<h2>2. How many American homeowners have flood insurance?</h2>
<p>It is difficult to determine exactly how many homeowners have flood insurance. </p>
<p>The National Flood Insurance Program <a href="https://www.fema.gov/policy-claim-statistics-flood-insurance">had just under five million policies in force</a> as of June 30. Of these policies, approximately 68 percent were on single-family homes and 21 percent on condo units. There is no source on how many private flood policies are in force, but my sense is that it is very small relative to the number of National Flood Insurance Program policies.</p>
<p>In recent years, the number of such policies has been dropping across the country. Some of the counties hardest hit by Harvey, for example, such as Harris (which includes Houston), <a href="http://abcnews.go.com/Politics/wireStory/flood-policies-plunge-houston-years-harvey-49513946">have experienced significant declines</a>.</p>
<p>A more revealing – and <a href="https://bsa.nfipstat.fema.gov/reports/1011.htm">more difficult to ascertain</a> – stat is the share of homeowners in a disaster area who actually have flood insurance. In Harris County, for example, <a href="http://abcnews.go.com/US/consumer-flood-insurance-wake-hurricane-harvey/story?id=49535161">experts estimate</a> that only about 15 percent of homeowners are insured for floods – though the percentage should be higher in areas near coastlines.</p>
<p>Real estate data company <a href="http://www.corelogic.com/about-us/news/media-advisory-corelogic-analysis-estimates-total-residential-insured-and-uninsured-flood-loss-for-hurricane-harvey.aspx">CoreLogic</a> estimates that approximately 70 percent of flood losses from Harvey will be uninsured.</p>
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<h2>3. Why do people at great risk of flooding forgo insurance?</h2>
<p>A <a href="https://riskcenter.wharton.upenn.edu/publications/">number of factors</a> affect a homeowner’s decision to buy flood insurance (or not). </p>
<p>People who perceive that their exposure to floods is high are more likely to buy it, all other things equal. And the <a href="https://www.fema.gov/faq-details/Mandatory-Purchase-of-NFIP-Coverage/">mandatory purchase requirement</a> forces owners of mortgaged homes located in Special Flood Hazard Areas – areas at high risk for flooding – to buy insurance. </p>
<p>However, 43 percent of homeowners <a href="http://www.iii.org/sites/default/files/docs/pdf/pulse-wp-020217-final.pdf">incorrectly believe</a> that their homeowners’ insurance covers them for flood losses. </p>
<p>Other factors also come into play, such as a lack of information, the difficulty of calculating flood risk and the expectation that the government will provide disaster assistance – which is <a href="https://www.nytimes.com/2017/08/30/business/harvey-aid-sba-disaster-loans.html?mcubz=1&_r=0">rarely the case</a>.</p>
<h2>4. What does flood insurance cover?</h2>
<p>With a <a href="https://www.fema.gov/media-library-data/20130726-1620-20490-4648/f_679_summaryofcoverage_11_2012.pdf">National Flood Insurance Program policy</a>, a homeowner can purchase coverage on a dwelling up to US$250,000 and the contents of a home up to $100,000. It does not cover costs associated with “loss of use” of a home. </p>
<p>The National Flood Insurance Program policy limits have been in effect since 1994 and need to be updated to account for the increase in the replacement cost of homes and the actual cash value of their contents. Although not the best measure of the replacement cost, the median price of new homes sold in the U.S. <a href="https://fred.stlouisfed.org/series/MSPNHSUS">has soared 132 percent</a> since 1994.</p>
<p>Some homeowners buy additional flood protection from private insurers to make up any shortfall. </p>
<h2>5. Why is the National Flood Insurance Program underwater?</h2>
<p>The National Flood Insurance Program <a href="http://www.gao.gov/assets/690/684354.pdf">has faced considerable criticism</a> over its underwriting and pricing policies, which have resulted in a substantial debt. Essentially, its premiums are not high enough to cover how much it pays out on claims and its other costs. </p>
<p>Part of the problem is that <a href="https://www.fema.gov/media-library-data/1382115115666-0fba8b9a68fef69d546513c6da105bbe/BW12_AgentWhat_to_Know_Say_Sect205_Sept2013.pdf">about 20 percent of the properties</a> the program insures pay a subsidized rate. But many other National Flood Insurance Program policyholders are also paying premiums <a href="http://www.foxbusiness.com/politics/2017/08/29/key-flood-insurance-underwriter-sinks-further-into-debt-as-harvey-slams-texas.html">substantially less</a> than what it costs to insure them because the rates do not adequately account for the catastrophic losses incurred during years when more major storms than normal strike, such as Katrina and Rita in 2005 and Sandy in 2012. As a result, the National Flood Insurance Program owes an accumulated debt of $25 billion to the U.S. Treasury.</p>
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<p>Hurricane Harvey (and potentially other storms such as Irma that may follow) will substantially increase this debt. <a href="http://www.corelogic.com/about-us/news/media-advisory-corelogic-analysis-estimates-total-residential-insured-and-uninsured-flood-loss-for-hurricane-harvey.aspx">CoreLogic estimates</a> that National Flood Insurance Program-insured flood losses from Harvey alone will be $6 billion to $9 billion.</p>
<p>In the short term, Congress will have to increase the National Flood Insurance Program’s borrowing authority for it to pay the claims that will result from Harvey and other storms this year. Lawmakers could make a general fund appropriation to forgive all or a portion of the National Flood Insurance Program’s debt, but it has shown no interest in doing so. </p>
<p>These inadequate rates also exacerbate the <a href="http://blogs.colgate.edu/economics/files/2014/09/McGee-2014-Moral-Hazard-and-the-National-Flood-Insurance-Program.pdf">moral hazard created by flood insurance</a>. People are more likely to buy, build or rebuild homes in flood-prone areas and have diminished incentives to invest in flood risk mitigation, such as by elevating their home, if they can buy insurance at below-cost rates. </p>
<h2>6. What can be done to fix the program?</h2>
<p>Legislative efforts to reform the National Flood Insurance Program to put it on firmer fiscal footing have produced mixed results. </p>
<p>The <a href="https://www.fema.gov/media-library/assets/documents/31946">Biggert-Waters Act of 2012</a> made a number of changes to the program, such as increasing premiums and other changes to make it “<a href="https://www.fema.gov/media-library-data/20130726-1912-25045-9380/bw12_qa_04_2013.pdf">more financially stable</a>,” that would have gone a long way to restore its fiscal solvency. However, an outcry from homeowners in high-risk areas such as coastal Florida led to the <a href="https://www.fema.gov/media-library/collections/414">Homeowners Flood Insurance Affordability Act</a>, passed in 2014, that limited or rescinded many of the Biggert-Waters rate increases. </p>
<p>Fundamentally, the program millions of Americans rely on to help them rebuild their lives after a devastating flood <a href="http://www.rff.org/research/collection/reforming-national-flood-insurance-program">needs to be fixed</a>. Its dire financial straits could be resolved by either making taxpayers foot more of the bill or increasing premiums closer to full-cost rates for most homeowners, while also raising total coverage levels.</p>
<p>At the same time, the government needs to do more to convince or compel more at-risk homeowners to buy flood insurance – which would be harder to do if it were to raise rates. To me, this suggests that increasing taxpayer support for the NFIP will have to be part of the solution so that pricey premiums don’t become a deterrent to someone buying insurance. </p>
<p>With the likelihood of much more flooding in the coming weeks and years, more needs to be done to mitigate the risk, including producing more accurate and timely maps of the flood risk in various areas, especially high-risk areas, educating people about what those risks really mean and helping relocate homeowners as necessary.</p><img src="https://counter.theconversation.com/content/83187/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert W. Klein does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The federal government created a program in 1968 to insure homes in the US from flooding, yet few of the houses hammered by Harvey’s record rainfall were covered.Robert W. Klein, Professor Emeritus of Risk Management and Insurance, Georgia State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/681702016-11-07T19:06:50Z2016-11-07T19:06:50ZPlanning for a rainy day: there’s still lots to learn about Australia’s flood patterns<p><em>The journal <a href="http://link.springer.com/journal/10584">Climatic Change</a> has published a <a href="http://link.springer.com/journal/10584/139/1/page/1">special edition</a> of review papers discussing major natural hazards in Australia. This article is the first in a <a href="https://theconversation.com/au/topics/australian-natural-hazards-series-32987">series</a> looking at those threats in detail.</em></p>
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<p>Recent floods in <a href="http://www.abc.net.au/news/2016-09-23/forbes-expecting-major-flood-residents-urged-to-prepare/7870582">New South Wales</a>, <a href="http://www.abc.net.au/news/2016-09-14/sa-homes-flooded-creeks-and-rivers-still-to-peak-ses-warns/7845572">South Australia</a> and <a href="http://www.abc.net.au/news/2016-09-15/victoria-weather-farmer-missing-homes-under-threat-avoca-river/7846214">Victoria</a> have reminded us of the power of our weather and rivers to wreak havoc on homes, business and even, tragically, lives. </p>
<p>As Dorothea Mackellar <a href="http://www.dorotheamackellar.com.au/archive/mycountry.htm">poetically pointed out</a>, “droughts and flooding rains” have been a feature of Australia throughout history, so maybe we shouldn’t be all that surprised when they happen.</p>
<p>However, we also know that the reported costs of flooding in Australia have been <a href="http://www.emdat.be/">increasing</a>, most likely through a combination of increased reporting, increased exposure through land use change and population growth, and changes to flood magnitude and severity. So it is critical that we understand what might be causing these changes.</p>
<p>This was the question we asked in our <a href="http://link.springer.com/article/10.1007/s10584-016-1689-y">review</a> on how flood impacts have changed over time in Australia and how they may change in the future. We found that despite decades of research in these areas, there are still many gaps in what we know.</p>
<h2>Copping a soaking</h2>
<p>We know that floods depend not just on how much rain falls, but also on how wet the ground is before a heavy rainfall, and how full the rivers are. We also have evidence that the storms that generate heavy rainfall will become more intense in the future, because as the atmosphere warms it can hold <a href="https://theconversation.com/why-warmer-storms-could-lead-to-more-flooding-than-expected-42825">more moisture</a>. </p>
<p>This is particularly the case for storms that last just a few hours; in fact we think that these storms are the most likely to show the largest increases. In urban environments this translates to an even greater flood risk, because the concrete and hard surfaces allow this intense rain to run off quickly through storm drains and into creeks and rivers, rather than seeping into the landscape.</p>
<p>In larger catchments and rural areas the story is more complicated than in cities. If the soil is very wet as a result of rain over the previous weeks and months, then when a big storm hits there will be a lot of runoff. In contrast, if the soil is dry then flooding is less likely to be a problem. </p>
<p>Engineers currently use simple models to estimate this relationship between soil wetness and storm rainfall. But our research indicates that these simple models will need to be replaced with longer-term simulations that model all of the previous rainfall leading up to the storm. </p>
<p>Simple models use simple assumptions to translate rainfall risk into flood risk. But if these assumptions are incorrect, our estimates of flood risk (that is, the probability of a given flood magnitude occurring in any particular year) could be wrong. Flood risk is used to guide infrastructure assessment through cost-benefit ratios, so getting it right is important.</p>
<p>One of the reasons that catchment wetness varies is because of climate cycles like El Niño and La Niña. We have some idea how these and <a href="https://theconversation.com/droughts-and-flooding-rains-it-takes-three-oceans-to-explain-australias-wild-21st-century-weather-56264">similar ocean cycles</a> affect our climate, including the fact that they can cause <a href="http://onlinelibrary.wiley.com/doi/10.1029/2002GL015992/abstract">fluctations in flood risk over decades-long timescales</a>. </p>
<p>The difficulty here is that for most locations we only have 50 to 60 years of recorded river flow data. This makes it hard to separate out the influences of these climate cycles from other trends in flood data, such as the effect of increasing urbanisation. </p>
<p>There has been progressively less monitoring of streamflow in Australia <a href="http://www.tandfonline.com/doi/abs/10.1080/13241583.2007.11465329">over the past few decades</a>, and this makes it even harder to understand regional changes in flood risk. Governments need to prioritise investment in data collection to allow us to improve our estimates of the risk of flooding and the associated damages now and in the future. </p>
<p>The recent work by the Bureau of Meteorology to develop a comprehensive set of high quality streamflow gauge <a href="http://www.bom.gov.au/water/hrs/">data</a> is a step in the right direction, but much more investment is needed in these areas.</p>
<p>Finally, we recommend that continued research into the fundamental changes likely from climate change is required. This requires climate models to be run at a range of resolutions to enable all the important climate processes for extreme rainfall to be properly represented. </p>
<p>Recent pressure on CSIRO’s climate modelling capabilities is concerning – the scientific questions are by no means fully answered on these topics. It is great to see the <a href="http://rses.anu.edu.au/news-events/new-arc-centre-excellence-climate-extremes">recent funding of the ARC Centre of Excellence on Climate Extremes</a>. The work of these researchers, combined with ongoing efforts across Australia, will be important to provide better assessments on climate changes. This can help engineers and hydrologists continue to provide accurate flood risk estimates.</p><img src="https://counter.theconversation.com/content/68170/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fiona Johnson receives funding from the Australian Research Council and World Health Organisation. </span></em></p><p class="fine-print"><em><span>Chris White receives funding from various Tasmanian State Government research funding programs, Wine Australia and the Bushfire and Natural Hazard CRC.</span></em></p><p class="fine-print"><em><span>Seth Westra receives funding from the Australian Research Council and various State Government research funding programs. </span></em></p>Floods are a costly part of Australian life, which means we need to get better at predicting exactly when - and how severely - they are likely to strike in the future.Fiona Johnson, Senior Lecturer, School of Civil and Environmental Engineering, UNSW SydneyChristopher J White, Lecturer in Environmental Engineering, University of TasmaniaSeth Westra, Associate Professor, School of Civil, Environmental and Mining Engineering, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.