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Imaggeo on Mondays: Cordillera del Paine

9 Jul

Cordillera del Paine by Martin Mergili, distributed by EGU under a Creative Commons licence.

Images such as the one above inspire scientists and nature lovers alike. This photograph, showing a Chilean landscape with elements representative of various Earth-science disciplines, is simply stunning. In a beautiful mix of shapes and colours, a quiet lake with floating icebergs appears tucked in between a roughed mountain in the background and a colourful double rainbow in the foreground.

The photographer, Martin Mergili of the University of Natural Resources and Life Sciences in Vienna, captured this inspiring scenery during a holiday trip a few years ago. The photo shows the eastern edge of the southern part of Cordillera del Paine, a “small but spectacular” mountain group in the Torres del Paine National Park, which is located in Chilean Patagonia almost 2,000 kilometres south of Santiago de Chile.

“The prominent peaks visible in the left portion of the image are the Cuernos del Paine,” Martin explains. “The rainbow in the foreground is not just decoration, it reflects the ever-changing weather patterns characteristic of that area. Even though it is located in the rainshade of the Cordillera at the edge of the semi-arid Patagonian lowlands, the westerlies bring a lot of moist air from the Pacific Ocean. The icebergs in the lake in the foreground (Lago Grey) originate from the large Glaciar Grey calving into the lake.”

More stunning images of this and other landscapes are available from Martin’s website.

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.

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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

Are we giants or ants? The future of hydrology discussed at the 2012 General Assembly

8 May

Today’s guest post, written during the 2012 General Assembly, comes from Eline Vanuytrecht from the Department of Earth and Environmental Sciences at KU Leuven, Belgium. This is her second post for GeoLog after her insightful piece on climate change and Portuguese wines. 

Keynote speakers, ‘giants’ in the field of hydrology, were invited to give their opinion on the path that hydrologists should follow in the coming decade to tackle future challenges.

Professor Keith Beven (University of Lancaster) opened the debate by criticizing the occasional abuse of hydrological models for prediction purposes.  Although the present demand from policy makers for accurate predictions and quick answers is oppressing, Beven requests his fellow hydrologists to be courageous in the coming decade and to dare to reject models. “Adopt the alternative view that models  are wrong until they are proven to be right. The process of rejection and the reflection on the question why a model should be rejected, brings us to a better understanding of the whole system that is modeled.” At the same time, Beven warns that the rejectionist framework he proposes entails the risk to abandon reliable models falsely. Next to this rejectionist framework, Beven emphasizes the need for improvement of observational techniques. “Observations are the ground on which widely used models are based. Disinformation, invoked by observations of inferior quality, should be avoided.”

Water featured prominently at the 2012 General Assembly (source: Wikimedia)

Professor Gordon Young (President International Association of Hydrological Sciences) started with a remarkable request. “In the coming decades, hydrologists should drop their unique subject of hydrology. Emphasis should also lie on water resources.” Young’s perspective is one of human needs and the permanent issue of water security. Water is essential for diverse human services, including food production, health care, energy production to sustain economies, preservation of ecosystems and a whole web of social interactions. At the same time, water resources can be threats for humankind in the form of floods, droughts, and pollution. It should be, according to Young, the mission of hydrologists to focus on these topics in the coming decades. Hydrological research should be embedded in a social, economical and political context.

Professor Thorsten Wagener (University of Bristol) increasingly descries water-related problems as a result of changes in climate, land use, and population dynamics. He assigns an important role to the hydrology community to solve these problems if they can acquire reliable predictive power in a changing world. According to Wagener, this is only possible if there is a continuous knowledge accumulation in the science of hydrology. “There are three complementary pathways to achieve this continuous scientific progress: good data accessibility, a focus on comparative or synthetic science, and an initiative structure of hydrological sciences.” According to Wagener, it is essential that data is reported uniformly and that it is accessible. Comparative scientific attitudes help to identify cases with a similar behavior in time and or space, crucial for knowledge transfer. Protocols should be designed to ensure uniformity and an easy knowledge transfer. The initiative structure refers to the attractiveness of hydrology. “It should be both inspirational and relevant.”

Professor Hubert Savenije (TU Delft) started his talk with focusing on the behavior of hydrologists. “Are we ants or are we giants?” The ants are without a doubt hardworking creatures, digging holes in the ground and coming up with surprising conclusions. But they see only a small part of the whole system. Instead, the overlooking perspective of giants is needed in the field of hydrology in the coming decades, according to Savenije. Landscapes and their hydrological processes should be mapped to the model space. “But it is often forgotten that the landscape is extensively determined by its medium. And this medium is an evolutionary product of a combination of morphological, ecological, hydrological and anthropological processes.” Hydrology should be approached from a Darwinian point of view in the coming decade. Hydrological processes should be understood in a co-evolutionary perspective, and once understood in this framework, equations can derived to describe important processes.

Concluding words came from Professor Xavier Sanchez-Vila (Universitat Politècnica de Catalunya). He dug deeper than his colleagues, literally, and focused his talk on hydrogeology, the science of deep groundwater. His concern is multi- and interdisciplinary work, which should not be disconnected from society needs. Sanchez-Vila argues that communication problems are at the basis of misunderstanding between disciplines, but also among hydrologists. “Four topics that deserve attention in the coming decade are ecohydraulics, water quality, uncertainty issues related to climate change and extreme events, and risk management. The solutions are often simple, but the problems are not.”

With these visionary talks, the keynote speakers may not only have touched important issues for the coming Hydrological Decade. A critical reflection may prove useful for the whole science community. Change is challenging.

By Eline Vanuytrecht, KU Leuven

On the Ground at GA2012: Water, water everywhere… including under the ice

24 Apr

Fresh from leading a team of UK geophysicists on a two-week campaign of seismic investigations in northern Sweden, Dr Adam Booth of Swansea University reports to us from the halls of the 2012 General Assembly in Vienna.

Hi, from a very sunny Vienna!   It’s my first day at the EGU General Assembly, and the whole city is under bright sunshine and blue skies.  Over the next few days, I’ll be blogging about presentations from within the Assembly’s Cryosphere division… Snow, ice, glaciers – the parts of the world that are typically much colder than the Austrian capital today!

My own role in cryospheric science is as a field geophysicist: I use various geophysical systems on the surface of glaciers and ice sheets to interpret the processes that are acting deeper down.  Some of the most fundamental influences on glacier flow act directly at the glacier bed, and much of my research effort is directed towards understanding the interaction between ice and its subglacial system.  What better way to kick off my conference, then, with sessions dedicated to ‘Subglacial Environments of Ice Sheets and Glaciers’?!

Attending this session leaves a field geophysicist somewhat staggered by the complexity of the problem!  Convened by Dr Bryn Hubbard (Aberystwyth University, UK), the session’s presenters consider the diverse and multi-scale interactions between a glacier and the material it sits on.  I therefore perused Monday’s presentations and poster programme with great interest, later catching up with some of the authors to get deeper into how we characterise the hidden subglacial world.  In places, it seems, that hidden world is a very wet one, and the influence of subglacial water is high on the agenda.  From its detection through to modelling its influence, and predicting how networks of water channels will evolve, there is water, water everywhere.

The influence of subglacial water on ice dynamics is a current hot-topic in glaciology.  Sebastian Goeller, together with colleagues at the Alfred Wegener Institute (AWI; Bremerhaven, Germany), has a truly multi-disciplinary take on understanding its relation to the Antarctic ice sheet.  Beneath Antarctica lie more than 300 subglacial lakes – vast reservoirs of water that are plumbed into a subglacial river network and.  The influence of these reservoirs is particularly strong where they are located close to the onset of ‘ice streams’, the fast-flowing conveyor belts that drain most of the ice that is lost from the continent.  Sebastian tells me how the AWI are developing a new computational model (called RIMBAY) that improves the representation of ice streams by including complex subglacial topography.  As a geophysicist, I’m used to seeing how dramatic that topography can be (for those who’ve seen Lord of the Rings, imagine a postcard from Mordor) – but current models typically consider a greatly-smoothed ice bed.  “It’s an enhanced modelling approach,” says Sebastian, “that gives better representation of the subglacial tributary system.”

Sebastian Goeller presents “Ice streams and subglacial lakes: the crucial impact of basal hydrology on ice sheet modelling (CR5.40, EGU2012-5225).

It certainly makes sense –by having RIMBAY route water through a more realistic network of channels, it more quickly pools beneath ice streams and enhances their flow velocity (see below).  RIMBAY is a complex beast, that takes quite a lot of computational power: Sebastian would like to see it applied to the whole Antarctic, but – for now – a small subsection close to the Recovery subglacial lakes will suffice!

Outputs from AWI’s RIMBAY subglacial water model, from Sebastian Goeller’s poster, showing the representation of a sinuous, fast-flowing, ice stream. Upper: an ice stream defined with a ‘conventional’ set of model parameters. The ice stream is visible, but is not well-defined. Lower: RIMBAY unleashed! Subglacial topography is honoured, and water flow is focused more effectively beneath the ice stream; it’s fast-flow characteristics become very well defined.

To make matters worse, a further complication in an already complex problem is that a subglacial water system can also evolve over relatively short time frames.  PhD student Tom Cowton (University of Edinburgh, UK) and Dr Paul Smeets (Utrecht University, Netherlands) interpreted changes in the subglacial drainage network beneath the West Greenland Ice Sheet, through respective dye tracing and glacier drilling programmes.  Their independent research points to the same conclusion: subglacial flow at the start of summer is sluggish – but with the erosive power of an increasing amount of meltwater, subglacial sediment is flushed out and an efficient drainage network develops.  Under such a regime, it is difficult to increase subglacial water pressure, and water then offers no influence on rapid ice sheet flow.

But a single summer is nothing to post-doc Nanna Karlsson (University of Copenhagen, Denmark), who takes the time-scale one step further.  Over the course of a few hundred years, Nanna’s work suggests that there can be major shifts in subglacial water flow that can cause entire regions of the ice sheet to stop moving altogether.  I’m surprised to learn how sensitive this relationship is: having identified subglacial flow pathways, Nanna observes that “just a few metres of surface elevation change can change subglacial flow quite dramatically” – which, to me, seems quite plausible under a warming climate scenario.

Nanna Karlsson presents “Subglacial drainage pattern of the northeast Greenland ice stream” (CR5.40, EGU2012-882).

Glaciers come in all shapes and sizes, but it seems that the underside of our ice masses might be just as variable as their surface.  Furthermore, the subglacial environment is clearly a complex place, and one that seems increasingly fundamental to understanding glacier dynamics.  I’ll be sure to keep a look out for evidence of these effects in my own geophysical data.

By Adam Booth, post-doc at Swansea University

Imaggeo on Mondays: Green river

2 Apr

Water dyed green runs down a thermokarst during a scientific experiment, by Simon Gascoin, distributed by EGU under a Creative Commons licence.

Thermokarsts occur when solid permafrost melts and soil gives way forming pitted, irregular lands surfaces. They are common in the Arctic, as well as the Himalayas and Swiss Alps. To study them, scientists trace the water using fluorescence dyes, temporarily creating water flows of exotic colours, like the bright green one in this Imaggeo photo.

This photo was taken by Simon Gascoin, a researcher at the Centre d’Etudes Spatiales de la Biosphère. “I took this picture during a field experiment near the Tapado glacier in the Andes of north-central Chile. All of the meltwater flowing from the glacier snout infiltrates in a thermokarst underground network and reappears in a proglacial spring located about 2km further downhill. The objective here was to determine the time of transfer between the infiltration hole and the spring, however, this particular experiment failed as we never observed the dye at the outlet! The hydrological dynamics in the Tapado watershed are currently being investigated by the CEAZA institute in Chile and Hydrosciences Montpellier,” he recollects.

In the context of environmental change, thermokarsts serve as effective geo-indicators of current and historic warming temperatures. However, they may also be directly formed by human activities, such as drilling and road construction.

See more of Simon Gascoin’s photography at https://sites.google.com/site/sgascoin/gallery

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: Reflecting mountains in Sørfjorden, Norway

12 Mar

A sunny morning in Sørfjorden by Martin Mergili, distributed by EGU under a Creative Commons licence.

Located just southeast of Bergen on the Norwegian Atlantic coast, Hardangerfjorden is the third longest fjord in the world, measuring more than 170 km from the Atlantic Ocean to the Hardangervidda mountain plateau. Its longest branch, Sørfjorden, cuts 50 km from the main fjord and ends at Odda.

Geormorphologist Martin Mergili visited the area in 2008, following the 33rd International Geological Congress in Oslo. “The photo was taken from the small town of Odda at the southernmost tip of the Sørfjord, a southern branch of the Hardangerfjord. The western slopes of the deeply incised fjord, which are shown on the photograph, lead up to the Folgefonna, one of the major ice fields of Norway. Partly glacierised highlands and deeply incised fjords are characteristic landforms of western Norway, formed during the Pleistocene. The picture was shot on a sunny and calm morning,” he recollects.

Fjords are formed by abrasion, when a retreating glacier cuts a U-shaped valley into the surrounding bedrock. They are primarily located in mountainous regions, against prevailing westerly marine winds that are orthogonally lifted over the mountains resulting in abundant snowfall to feed the glaciers. Coasts featuring the most pronounced fjords can be found in western Norway, northwestern North America, and southwestern New Zealand.

To view more from Martin Mergili’s collection of photos, many of which have geoscientific relevance, please visit: www.mergili.at/worldimages.

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: Huts in Arcachon Bay

16 Jan

The Tchanquees Huts in the Arcachon Bay by Yann Vitasse, distributed by EGU under a Creative Commons licence.

Yann Vitasse, now a researcher at the Institute of Botany, University of Basel in Switzerland, got a wonderful present in 2009 for completing his PhD: a flight on an ultralight aircraft above the southwest coast of France. It was then he took this stunning photo of the Arcachon Bay, a water area near Bordeaux that is fed by the Atlantic Ocean and by a number of fresh waterways.

“Here you see the famous Tchanquees Huts which were built on stilts in the middle of the Arcachon Bay, on the bird island. These huts were originally used for monitoring oyster beds,” Vitasse said.

The photo was taken at low tide, a time when the water covers an area of only 40 square kilometres. By comparison the bay takes up some 150 square kilometers at high tide, when the entire area to the left of the huts is covered by sea water.

The bird island, starting to the right of the huts, also varies in area being some 10 times larger at low tide. Geologists are still out on the origin of this structure. Some defend it is a former sandbar while others prefer the theory that it formed from the remains of a high dune shaped by the wind and the ocean.

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: Frozen river meets the sea

2 Jan

Frozen Lena-Delta by Thomas Ernsdorf, distributed by EGU under a Creative Commons licence.

This image shows part of the frozen delta of the Siberian River Lena. Thomas Ernsdorf, a researcher at the Department of Environmental Meteorology, University of Trier in Germany, took this photo during a Russian-German expedition to the Laptev Sea, the largest ice factory of the Arctic Ocean, in April 2008.

“The main goal of the expedition was to investigate the polynia (large open water and thin ice areas surrounded by land or thick ice) dynamics in the Laptev Sea. This scene was captured during a trip on the frozen Lena Delta from Tiksi to the Lena Delta Reserve,” explained Ernsdorf.

The Lena River is one of the longest in the world, flowing north from Lake Baikal in southern Russia for 4,400 kilometres. At the Laptev Sea, the Lena forms a delta with 32,000 square kilometres in area. This is the largest Arctic delta and is a protected wilderness area in Siberia.

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: Stretching to the Light

31 Oct

Stretching to the Lights, Bryce Canyon, Utah, USA. Image by Valeria Volpe, 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.