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Geosciences column: What drives changes in flood risk?

6 Jun

After a couple of months of absence, GeoLog is once again hosting the Geosciences column. This month we have no less than two posts highlighting recent research in the Earth sciences. In the second of this month’s columns, Eline Vanuytrecht writes about recent research on flood risk published in the EGU journal Natural Hazards and Earth System Sciences.

If you’d like to contribute to GeoLog, please contact EGU’s Media and Commmunications Officer, Bárbara T. Ferreira at media@egu.eu.


Floods can cause serious damage in residential areas. Recent records show that the damage has increased over the last decades, placing floods as one of the most severe natural hazards. But what exactly was the main cause for this increase in damage? And how will the relative contribution of drivers of flood-risk change such as meteorological phenomena, land use and socio-economic developments evolve in the future?

Heavy precipitation, flood and measurements, by Bibiana Groppelli. Distributed by EGU under a Creative Commons licence

To answer these questions, a group of German researchers, led by Florian Elmer of the GFZ Research Centre for Geosciences in Potsdam, analyzed what drives changes in flood risk in the lower part of the Mulde River basin in Eastern Germany. They concluded, rather surprisingly, that land-use changes, not meteorological phenomena, are the main drivers of flood risk change.

“Consequently, the potential influence of local and regional land-use policies is substantial and could contribute significantly to (…) risk mitigation,” the authors write in the Natural Hazards and Earth System Sciences paper.

The study focused on the lower Mulde River catchment  but it can serve as bench-mark for complete risk analysis for other river systems. Flooding is common in this catchment, which comprises several municipalities and an area of approximately 1000km² of which around 8% is inhabited.

The scientists surveyed the change of flood risk in terms of expected annual damage in residential areas between 1990 and 2020 in 10-year time steps. The analysis was based both on observations (for the past period) and model projections (for future times). They further quantified how the cost and impact of floods are modified by each of these drivers: climate change, land-use change and changes in building values.

The results of the study show that, under changing meteorological conditions, including altering rainfall patterns and rising temperatures, only few changes in return time of floods of different magnitude are experienced. The return time of a flood is a measure for its frequency, which reflects the estimated average time between two events.

Predicted increases in flood risk are thus mainly related to land-use changes including paving of previously permeable surfaces. Since 1990, the region has undergone major socio-economic changes after the reunification of Germany, including population decrease. However, at the same time, the area saw urban sprawl and residential structure change towards single-family dwellings. This expansion of urban areas increases the area covered by impermeable pavements, hence increasing flood risk. The scientists expect to see more urbanization, and thus increased risk, in the future.

Interestingly, the monetary value of the estimated annual flood damage decreased from 1990 to 2000. This is due to a combination of factors after Germany’s reunification leading to an exceptional situation of high inflation after 1990. In the future, however, the authors predict increasing damage values.

Another interesting conclusion is that small to moderate flood events dominate the risk expectation. These events combine relatively small flood volumes with a high return time (less than 20 years).

The results of the research hold an important message for flood-risk policy. Since land-use change is identified as the main driver of flood-damage change, a key role is reserved for land-use policies in risk mitigation. Further, since the majority of the annually expected damage can be attributed to small to moderate floods occurring frequently, relatively easy-to-install protection measures can erase substantial part of the damage.

By Eline Vanuytrecht, freelance writer & PhD student, KU Leuven

Publications by the EGU

10 May

The EGU is responsible for 14 Open Access journals, all freely available online

Since 2001, the EGU and Open Access publishing house Copernicus Publications has published a growing number of successful geoscientific journals. These include 14 peer-reviewed Open Access journals, of which 11 have a Thomson Reuters Impact Factor, placing them in the top echelon of their respective discipline. EGU also publishes a host of other materials available in paper and online. As a signatory of the Berlin Open Access Declaration (2003), the EGU is committed to making all their publications freely available.

The EGU’s Open Access scientific journals are:


Following today’s earthquake in Sumatra online

11 Apr

This blogpost is a round-up of potentially useful weblinks to information about the earthquake off the west coast of northern Sumatra of 11 April 2012. The links provided here are external and do not reflect the opinions of the European Geosciences Union.

Real-time seismic monitor (source: IRIS)

Regarding the earthquake, the US Geological Survey’s  (USGS) Earthquake Harzard Program homepage features seismic activity maps and a summary of the event. The USGS also has a map and list of earthquakes in the Asia region, showing aftershocks in real time on a map.

Concerning the tsunami, the Pacific Tsunami Warning Center, run by the National Oceanic & Atmospheric Administration, has its own pages and a specific one on today’s activity.

The Global Disaster Alert and Coordination System also has various models related to the earthquake and tsunami.

Finally, the IRIS Seismic Monitor has lots of resources designed for teaching, including a Powerpoint presentation and animations. The Harvard Seismology page also contains research and animations.

Thank you to Charlotte Krawczyk, president of the EGU seismology division, for providing these links.

Imaggeo on Mondays: Zurich lit by lightning

30 Jan

Zurich lit by lightning by Ryan Teuling, distributed by EGU under a Creative Commons licence.

In Zurich, Switzerland, June is often the wettest month of the year. Summer thunderstorms that give clouds a purple-grey colour and bright up the skies with strong lightning bolts are common place. This picture, taken by Ryan Teuling from Wageningen University in the Netherlands, captures one of these bolts, lighting up the centre of the city.

Teuling took this photo in June 2008 when he worked at the Institute for Atmospheric and Climate Science (CHN) in Zurich, following the Institute’s yearly barbecue.

“From the upper floor of the CHN building we had a great view of the centre of Zurich, the lake, and the active lightning. The lightning was so intense that I could take the picture by controlling the shutter by hand in response to lightning flashes, and not in automatic or repeat mode,” Teuling said. The storm front was stationary over Lake Zurich, visible in the centre of the frame, he added.

Thunderstorms occur when warm, moist air rises rapidly upwards, cools and condenses forming clouds and water droplets. These strong convective cells of air develop easily in the diverse topography of Zurich, a city located in a valley in the north tip of Lake Zurich, near the Albis chain of hills.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Volcanic twilight

19 Dec

Volcanic twilight by Robin Campion, distributed by EGU under a Creative Commons licence.

Mount Etna, located in the east coast of Sicily in Italy, is one of the most active volcanos in the world and is home to spectacular eruptions. This photo, taken by Robin Campion from the Université Libre de Bruxelles in Belgium, shows bright-red lava and a smoking scoria cone on the upper east flank of the volcano during an eruption in 2006.

“Fast-flowing lava flow was erupted from an eastwards trending fissure connected to the southeast crater. The crater itself was subject to short-lived (a few hours) episodes of intense explosive activity, separated by 2-3 days of repose and mild ash emissions,” Campion described.

Interestingly, the scoria cone seen in the picture is now buried under several meters of lava erupted this year by the southeast crater.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Rock Fall

21 Nov

Rock Fall. Image by Fausto Guzetti, distributed by EGU under a Creative Commons licence.

The photograph shows a rock fall occurred near Valtopina, Umbria, Central Italy, at an unknown date.

Rockfalls are a mass movement hazard. They mostly occur on steep rock faces, with the blocks that fall detaching along an existing weakness. The scale of a rock fall can range from a few blocks of rock to rock avalanches. Rock falls can be triggered by earthquakes, freeze-thaw or no apparent cause.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

EGU General Assembly 2012 Call for Papers

9 Nov

Abstract submission for the EGU General Assembly 2012 (EGU2012) is now open. The General Assembly is being held from Sunday 22 Apr 2012 to Friday 27 Apr 2012 at the Austria Center Vienna, Austria.

You can browse through the Sessions online.

Each Session shows the link Abstract Submission. Using this link you are asked to log in to the Copernicus Office Meeting Organizer. You may submit the text of your contribution as plain text, LaTeX, or MS Word content. Please pay attention to the First Author Rule.

The deadline for the receipt of Abstracts is 17 January 2012. In case you would like to apply for support, please submit no later than 15 December 2011. Information about the financial support available can be found on the Support and Distinction part of the EGU GA 2012 website.

Further information about the EGU General Assembly 2012 on it’s webpages. If you have any questions email the meeting organisers Copernicus.

Imaggeo on Mondays: Lava flow into sea

7 Nov

Lava from the East Rift Zone entering the sea near Kalapana (Hawaii Big Island). Image by Martin Mergili, distributed by EGU under a Creative Commons License.

The image shows a flow of basaltic lava out of a lava tunnel into the sea. The location of the scene is the shoreline of Hawaii Big Island near the village of Kalapana. Flow direction of the lava is from the bottom to the top of the image, vaporization of sea water leads to a steam plume of considerable size. Originating from the East Rift Zone, many of the lava flows in that area occur beneath a layer of partially solidified lava. The image was taken on August 13, 2010 during a touristic helicopter flight on a holiday trip.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Waterworld

5 Sep

Modern coral reefs surround an island formed from a dacitic dyke, part of the Pliocene volcanic rocks of Ambon, Moluccas, Indonesia. Image by Ian Watkinson, distributed by EGU under a Creative Commons License.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Imaggeo on Mondays: Storm

22 Aug

Image by Jorge Mataix-Solera, distributed by EGU under a Creative Commons License.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.