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floods

August GeoRoundUp: the best of the Earth sciences from around the web

August GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, major geoscience headlines, as well as unique and quirky research, this monthly column aims to bring you the latest Earth and planetary science news from around the web.

Major story

The south Indian state of Kerala has suffered unusually heavy monsoon rainfall this month, triggering the worst flooding the state has seen in more than a century.

Officials have reported nearly 500 deaths, while more than one million people have been evacuated to over 4,000 relief camps.

Between 1 and 19 August, the region received 758.6 milimetres of rain, 2.6 times the average for that season. In just two days (15-16 August), Kerala sustained around 270 milimetres of rainfall, the same amount of rainfall that the entire state receives in one month typically, said Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology and the National Oceanic and Atmospheric Administration, to BBC News.

Due to the heavy downpours, rivers have overflowed, water from several dams has been released, and lethal landslides have swept away rural villages.

“Officials estimated about 6,000 miles (10,000km) of roads had been submerged or buried by landslides,” reported the Guardian. “Communications networks were also faltering, officials said, making rescue efforts harder to coordinate.”

Experts report that the event’s severity stems from many factors coming together.

For instance, a recent study led by Koll has shown that in the past 50-60 years, monsoon winds have weakened, delivering less rain on average in India. However, the distribution of rainfall is uneven, with long dry spells punctuated by heavy rainfall events. Koll’s research suggests that central India has experienced a threefold rise in the number of widespread extreme rain events during 1950-2012. In short, it doesn’t rain as often; but when it rains, it pours.

Scientists also say that increased development in the region had exacerbated the monsoon’s impact.

For example, usually when storms release heavy rainfall, much of that water is absorbed or slowed down by vegetation, soil, and other natural obstacles. However, scientists point out that “over the past 40 years Kerala has lost nearly half its forest cover, an area of 9,000 km², just under the size of Greater London, while the state’s urban areas keep growing. This means that less rainfall is being intercepted, and more water is rapidly running into overflowing streams and rivers.”

To make matters worse, increased development can also change how effectively rivers handle heavy downpours. For instance, canals and bridges can make rivers more narrow and can create sediment build-up, which slows water flow. “When there is a sudden downpour, there is not enough space for the water so it floods the surrounding area,” explains Nature.

Some experts have added that badly-timed water management practices are also partly to blame for the flood’s devastation on local communities.

“A contributing factor is that after the heavy rain, authorities began to release water from several of the state’s 44 dams, where reservoirs were close to overflowing. The neighbouring state of Tamil Nadu also purged water from its over-filled Mullaperiyar dam, which wreaked yet more havoc downstream in Kerala,” Nature adds.

While floodwaters began to recede in late August, rescue teams are still searching submerged neighborhoods to deliver aid and evacuate survivors.

What you might have missed

Water on moon confirmed

Recent research published this month suggest that there is almost certainly frozen water on the moon’s surface.

The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right). Blue represents the ice locations, plotted over an image of the lunar surface, where the gray scale corresponds to surface temperature (darker representing colder areas and lighter shades indicating warmer zones). (Credit: NASA)

“Previous observations indirectly found possible signs of surface ice at the lunar south pole, but these could have been explained by other phenomena, such as unusually reflective lunar soil,” NASA officials said in a published statement.

Now, scientists involved with the new study claim that they’ve found definitive evidence that ice is located within craters on the moon’s north and south poles.

During daylight hours, the moon’s surface can be brutally hot, often reaching temperatures as high as 100 degrees Celsius. However, due to the moon’s axial tilt, some parts of the lunar poles don’t receive sunlight. Scientists estimate that some craters situated within these permanently dark polar regions are cold enough to sustain pockets of water-ice.

Because the moon’s poles are so dark, scientists have had a hard time studying the lunar craters. But Shuai Li, a planetary researcher at the University of Hawaii at Manoa and lead author of the study, and his colleagues tried a creative way to shed some light on shadowed craters, using data collected from India’s Chandrayaan-1 lunar probe ten years ago.

“They peered into dark craters using traces of sunlight that had bounced off crater walls,” reports the New York Times. “They analyzed the spectral data to find places where three specific wavelengths of near-infrared light were absorbed, indicating ice water.”

As of now, the researchers still aren’t sure how much ice there is, or how it found its way to the moon’s poles. But if enough accessible ice exists close to the lunar surface, the water could be used as a resource for future missions to the moon, from a source of drinking water to rocket fuel.

Mapping Earth’s winds from above

Also this month, scientists from the European Space Agency launched a satellite that will profile the world’s winds, in hopes that the data will greatly improve weather forecasts and provide insight for long-term climate research. The satellite, named Aeolus after the celestial keeper of the winds in Greek mythology, was sent to orbit from French Guiana on Wednesday 22 August.

The rocket was due to lift off on Tuesday, but the launch was postponed – ironically – due to high altitude winds,” reports BBC News.

Aeolus profiling the word’s winds (Credit: ESA)

Equipped with a Doppler wind lidar, Aeolus will send powerful laser pulses down to Earth’s atmosphere and measure how air molecules and other particles in the wind scatter the light beam.

Researchers expect that wind data from Aeolus will greatly improve current efforts to forecast storms, especially their severity over time. While scientists have many ways to measure wind behavior, current methods are unable to capture wind movement from all corners of the Earth. Aeolus will be the first mission to monitor winds across the entire globe.

Using data collected by Aeolus, experts estimate that the quality of forecasts will increase by up to 15% within the tropics, and 2-4% outside of the tropics.

“If we improve forecasts by 2%, the value for society is many billions of dollars,” said Lars Isaksen, a meteorologist at the European Centre for Medium-Range Weather Forecasts (ECMWF), to Nature.


Learn how Earth’s wind is generated and why we need to measure it. (Credit: ESA

Links we liked

The EGU story

Do you enjoy the EGU’s annual General Assembly but wish you could play a more active role in shaping the scientific programme? Now is your chance! Help shape the scientific programme of the 2019 General Assembly.

Before the end of today (6 September), you can suggest:

This month we released two press releases from research published in our open access journals. Take a look at them below:

Landslides triggered by human activity on the rise

More than 50,000 people were killed by landslides around the world between 2004 and 2016, according to a new study by researchers at UK’s Sheffield University. The team, who compiled data on over 4800 fatal landslides during the 13-year period, also revealed for the first time that landslides resulting from human activity have increased over time. The research is published today in the European Geosciences Union journal Natural Hazards and Earth System Sciences.

Deadline for climate action – Act strongly before 2035 to keep warming below 2°C

If governments don’t act decisively by 2035 to fight climate change, humanity could cross a point of no return after which limiting global warming below 2°C in 2100 will be unlikely, according to a new study by scientists in the UK and the Netherlands. The research also shows the deadline to limit warming to 1.5°C has already passed, unless radical climate action is taken. The study is published today in the European Geosciences Union journal Earth System Dynamics.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

Imaggeo on Mondays: Why is groundwater so important?

Imaggeo on Mondays: Why is groundwater so important?

Groundwater is an often underestimated natural resource, but it is vital to the functioning of both natural and urban environments. Indeed, it is a large source of drinking water for communities world-wide, as well as being heavily used for irrigation of crops and crucial for many industrial processes. The water locked in the pores and cracks within the Earth’s soils and rocks, also plays an important role in the recharge of water in lakes, rivers and wetlands, as Anna Menció explains in today’s Imaggeo On Monday’s post.

The Pletera salt marsh area (NE Spain) is located in the north of the mouth of the Ter River, in a region mainly dominated by agriculture and tourism activities. Some of the coastal lagoons and wetlands in this area have been affected by the incomplete construction of an urban development. These wetlands and lagoons are the focus of a Life+ project, which aims to restore this protected area, and to recover its ecological functionality.

The Pletera coastal lagoons are periodically flooded by both, freshwater from streams and seawater, during storm events. However, the surface water inputs alone are insufficient to maintain them as permanent lagoons.

This picture is of Fra Ramon lagoon, one of the natural lagoons in the area. The preliminary results of a recent study showed that the recharge of Fra Ramon is dependent on groundwater inputs. In most of the sampling campaigns, freshwater from the aquifer may account for >50% of the lagoon water.

The ecological quality of these lagoons is also affected by nitrogen inputs, mainly produced during flooding events. Although in this area nitrate pollution is also detected in groundwater, with concentrations up to 100 mg NO3/L, natural attenuation processes in the aquifer occur. Effects of these processes are particularly detected close to the lagoons area, where low nitrate concentrations in groundwater are observed, with values below the detection limit. Considering that groundwater may present lower nitrogen concentrations than surface inputs observed during flooding events, these results reinforce the importance of groundwater dynamics in these systems, not only to maintain the permanent lagoons during dry periods, but also to preserve their quality.

By Anna Menció, researcher at the Department of Environmental Sciences of the University of Girona.

Acknowledgments: the study of the Pletera coastal lagoons is founded by LIFE 13 NAT/ES/001001, MINECO CGL-2014-57215-C4-2R, and UdG MPCUdG2016/061 projects.

 

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Geoscience hot topics – The finale: Understanding planet Earth

Geoscience hot topics – The finale: Understanding planet Earth

What are the most interesting, cutting-edge and compelling research topics within the scientific areas represented in the EGU divisions? Ground-breaking and innovative research features yearly at our annual General Assembly, but what are the overarching ideas and big research questions that still remain unanswered? We spoke to some of our division presidents and canvased their thoughts on what the current Earth, ocean and planetary hot topics will be.

Because there are too many to fit in a single post we’ve brought some of them together in a series of posts which will tackle three main areas. The first post focused on the Earth’s past and its origin, while the second post focused on the Earth as it is now and what its future looks like. Today’s is the final post of the series and will explore where our understanding of the Earth and its structure is still lacking. We’d love to know what the opinions of the readers of GeoLog are on this topic too, so we welcome and encourage lively discussion in the comment section!

A new, modern, era for research

That we have great understanding of the Earth, its structure and the processes which govern how the environment works, is a given. At the same time, so much is still unknown, unclear and uncertain, that there are plenty of research avenues which can help build upon, and further, our current understanding of the Earth system.

By Camelia.boban (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Big Data’s definition illustrated with text. Credit: Camelia.boban (Own work) [CC BY-SA 3.0], via Wikimedia Commons

As research advances, so do the technologies which allow scientist to collect, store and use data. Crucially, the amount of data which can be collected increases too, opening avenues not only for scientists to carry out research, but for the wider population to be involved in scientific research too: the age of Big Data and Citizen Science is born.

The structure of the Earth

Despite a long history of study, including geological maps, studies of the structure of the Alps, and the advent of analogue models some 200 years ago, there is much left to learn about how geological processes interact and shape our Earth.

Some important unanswered questions in the realm of Tectonics and Structural Geology (TS) include:

“Why do some passive margins have high surface topography (take Norway, or Southeastern Brazil as an example) even millions of years after continental break-up? How does subduction, the process by which a tectonic plate slides under another, begin? And how does the community adapt to new research methods and ever growing datasets?” highlights Susanne Buiter, TS Division.

One important problem is that of inheritance and what role it plays in how plate tectonics work. Scientists have known, since the theory was first proposed in the 1950s (although it only became broadly accepted in the 1970s), that our planet is active: its outer shell is divided into tectonic plates which slide, collide, pull away and sink past one another. During their life-time the tectonic plates interact with surface process and eventually flow into the mantle below. This implies that any new tectonic processes will take place in material that carries a history.

“It is increasingly recognised that tectonic events do not act on homogenous, pristine materials, but more likely on crust that is cross-cut by old shear zones, incorporates different lithologies and which may have inherited heat from previous deformation events (such as folding),” explains Susanne.

So the key is: what is the impact of historical inheritance on tectonic events? Can old structures be reactivated and if so, when are they reactivated and when not? Do the tectonic processes control the resulting structures or is it the other way around?

Seismology too can shed more light on how we understand Earth processes and the structure of the planet.

“An emerging field of research is seismic super-resolution: a promising technique which allows imaging of the fine-scale subsurface Earth structure in more detail than has been possible ever before,” explains Paul Martin Mai, President of the Seismology (SM) Division.

The methodology has applications not only for our understanding of the structure and process which take place on Earth, but also for the characterisation of fuel reservoirs and identification of potential underground storage facilities. That being said, the technique is still in its infancy and more research, particularly applied to ‘real’ geological settings is needed.

Understanding natural hazards

The reasons to pursue further understanding in this area are diverse and wide-ranging: amongst the most relevant to society is being able to better comprehend and predict the processes which lead to natural disasters.

Earthquake 1920 (?). Credit: Konstantinos Kourtidis (distributed via imaggeo.egu.eu)

Earthquake 1920 (?). Credit: Konstantinos Kourtidis (distributed via imaggeo.egu.eu)

It goes without saying that, due to their destructive nature, earthquakes are a topic of continued cross-disciplinary scientific research. Generating more detailed images of the Earth’s structure, using seismic super-resolution for instance, can also improve our understanding of how and why earthquakes occur, as well as helping to determine large-scale fault behaviour.

And what if we could crowd source data to help us understand earthquakes better too? LastQuake is an online tool, operated via Twitter and an app for smartphones which allows users to record real-time data regarding earthquakes. The results are uploaded to the European-Mediterranean Seismological Centre (EMSC) website where they offer up-to-data information about ongoing shake events. It was used by over 8000 people during the April 2015 Nepal earthquakes to collect eyewitness observation, including geo-located pictures, testimonies and comments, in the immediate aftermath of the earthquake.

In this setting, citizens become scientists too. They contribute data, by acquiring it themselves, which can be used to answer research questions. In the case of LastQuake, the use of the data is immediate and can contribute towards easing rescue operations and alerting citizens of dangerous areas (for instance where buildings are at risk of collapse) providing a two-way communication tool.

Global temperatures and climate change

It is not only earthquakes that threaten communities. Just as destructive can be extreme weather events, such as typhoons, cyclones, hurricanes, storm surges, severe rainfalls leading to flooding or droughts. With the increased frequency and destructiveness of these events being linked to climate change understanding global temperature fluctuations becomes more important than ever.

Flooded Mekong. Credit: Anna Lourantou (distributed via imaggeo.egu.eu)

Flooded Mekong. Credit: Anna Lourantou (distributed via imaggeo.egu.eu)

Over periods of months, years and decades global temperatures fluctuate.

“Up to decades, the natural tendency to return to a basic state is an expression of the atmosphere’s memory that is so strong that we are still feeling the effects of century-old fluctuations,” says Shaun Lovejoy, President of the Nonlinear Processes Division (NP).

Harnessing the record of past-temperature fluctuations, as recorded by the atmosphere, can provide a more accurate way to produce seasonal forecasts and long-term climate predictions than traditional climate models and should be explored further.

Geoscience hot topics

Be it studying the Earth’s history, how to sustainably develop our communities, or simply understanding the basic principles which govern how our planet – and others – operates, the scope for avenues of research in the geosciences is vast. Moreover, the advent of new technologies, data acquisition and processing techniques allow geoscientists to explore more complex problems in greater detail than was ever possible before. It’s an exciting time for geoscientific research.

By Laura Roberts Artal in collaboration with EGU Division Presidents

GeoTalk: Want a record of historical floods? Ask the taxman

Extreme weather events, like catastrophic floods, are the malicious exclamation points of Earth’s chaotic and variable climate system; they arrive without warning and extract huge costs, both economic and humanitarian, from the communities they strike. Evidence suggests the frequency and severity of these events may be on the rise in a changing climate, but scientists struggle to place modern events in a longer historical context.

Information about the past hides in all kinds of places. The trick is figuring out how to extract it. Rudolf Brázdil and his team from Masaryk University in Brno have started using historical tax records from southern Moravia in the Czech Republic to reconstruct the flood history of the area, a test case for broader studies of this kind. At the EGU General Assembly, Brázdil sat down with Julia Rosen to explain his approach.

To start with, how did this idea occur to you?

Existing hydrological series based on instrumental records are generally short. To study really disastrous events, which have a long recurrence interval, you cannot use just the period of hydrological measurements, you have to extend it into the past. We are working in the field of historical hydrology using documentary sources to reconstruct past floods and we recognised that we can use this so-called taxation data. In the past, in Moravia, if anybody was affected by any disastrous events – like a flood – they had the opportunity to ask to pay lower taxes. It was a complicated administrative process, and we are studying documents related to this process to reconstruct hydrometeorological events – including floods. The idea is to obtain the longest series of extremes as possible.

A painting from 1846 commemorating the tragic Elbe flood of March 1845 in Ústí nad Labem, NW Bohemia. The peak discharge of this flood was not matched even by the disastrous August 2002 event. (Credit: Museum of the City of Ústí nad Labem, Oil on wood, painted shooting target, catalogue no. U 334)

A painting from 1846 commemorating the tragic Elbe flood of March 1845 in Ústí nad Labem, NW Bohemia. The peak discharge of this flood was not matched even by the disastrous August 2002 event. (Credit: Museum of the City of Ústí nad Labem, Oil on wood, painted shooting target, catalogue no. U 334)

How do you actually infer flood histories from these data?

Using this data, you can recognise the time and place of an event and its impacts. That’s because the original aim of these documents was to describe damage for which affected people could obtain some tax relief. Generally, you can use flood marks to determine the size of events. For example, people identified the height of the water on the bridge, or on the wall of the house. In Prague (where I have worked before) there is a statue – the head of a bearded man – that was installed in the 15th century. People have characterised floods with respect to how much of the head was submerged, or if it disappeared entirely, since 1481. People knew, for example, that if the water reached the head, they had to leave their houses.

You also know the flooded area by which villages or settlements have been affected. It is difficult to precisely compare the magnitude of historical floods with recent floods because of the totally different character of rivers in the past. They were not regulated – they had many meanders and the character of the landscape was different as well. But we can still compare events from the point of view of the frequency of floods, their seasonality and impacts.

What are the challenges of working with this kind of data? What are its limits?

Every proxy is limited from different points of view. One limitation of our data is incompleteness, both spatially and temporally. For example, you could have a situation where nobody recorded such events, although this is not so likely when events are really strong. Second, perhaps someone recorded it, but original records were lost in fires or during reorganisation of archives. Third, of course, it is generally qualitative information. You need to understand the nature of these data by collaborating with historians and archivists. I am a climatologist, and for me, it’s extremely important to cooperate with such people because without them, there wouldn’t be any historical hydrology. On the other, they would never use such data for the purposes for which we are using it. It is a classic example of interdisciplinary research.

What did you find? Has the frequency of extreme floods increased or decreased?

We are more or less at the beginning of this project using taxation records in Moravia. I am just now evaluating everything, so it’s difficult for me to say now. However, I can give you an example from Bohemia (the western part of the Czech Republic) where we have worked before using other kinds of documents. There, the 19th century was an extremely active period for floods, followed by the second part of the 16th century. The second part of the 20th century was very quiet in the Czech Lands, there were really no important floods until the disastrous floods of July 1997 in Moravia and August 2002, in Bohemia.

The Long Bridge across the River Svratka in Brno where ice floes accumulated during the flood of March 1830 after the extremely severe winter of 1829-1830. (Reproduction of a colour drawing by Frantisek Richter, Brno City Archives, Collection of graphics, prints and reprints, no. 255R)

The Long Bridge across the River Svratka in Brno where ice floes accumulated during the flood of March 1830 after the extremely severe winter of 1829-1830. (Reproduction of a colour drawing by Frantisek Richter, Brno City Archives, Collection of graphics, prints and reprints, no. 255R)

What comes next?

For this project, the first step was tax records. The second step is family archives, which sometimes contain better information, and the third step is chronicles, then newspapers, and of course systematic hydrologic and meteorological measurements. This should form the main database to allow us to do our analysis and synthesis. Success will be if we are able to analyse in detail the spatial and temporal variability of hydrometeorological extremes for the last 350 or 400 years and to use this information for estimates of future extremes.

It will also be a success for us if our work gains acceptance within the international community. This will demonstrate that we are presenting new and interesting results and new methodological approaches that might be applicable on a broader scale. I believe these taxation data are available in many European countries and it would help to extend our knowledge about past floods in this area.

By Julia Rosen, PhD, Freelance Science Writer

Acknowledgement:

The project is financed by the Czech Republic Grant Agency.