GeoLog

hydrological sciences

GeoTalk: Making their mark: how humans and rivers impact each other

GeoTalk: Making their mark: how humans and rivers impact each other

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Serena Ceola, a hydrologist and assistant professor at the University of Bologna, Italy, who studies interactions between humans and river systems. At the upcoming General Assembly she will be recognised for her research contributions as the recipient of the 2019 Hydrological Sciences Division Outstanding Early Career Scientists Award.

Thanks for talking to us today! Could you introduce yourself and tell us a little more about your career path so far?

I was born in Padova, Italy, and studied environmental engineering at the University of Padova, from which I obtained a master’s degree in 2009. Since my bachelor’s studies, I was fascinated by hydrology: both my bachelor’s and master’s thesis dealt with the availability of river discharge, which is the amount of water flowing through a river channel.

Then, in 2009 I moved to Lausanne in Switzerland and I continued my studies with a PhD at the Laboratory of Ecohydrology of the École Polytechnique Fédérale de Lausanne (EPFL). My PhD thesis focused on the implications of river discharge availability on river ecosystems (namely algae and macroinvertebrates). Since 2013, I have been based at the University of Bologna, Italy, currently as a junior assistant professor. Now my main research project focuses on the relationship between river discharge availability and human activities, both at local and global scales.

Serena Ceola collecting benthic macroinvertebrates used for a small-scale flume experiment in Lunz-Am-See, Austria. (Photo Credits: Serena Ceola)

What got you interested in environmental engineering and hydrology? What brought you to study this particular field?

Studying environmental engineering was the perfect trade-off between being an engineer and focusing on environment sustainability and protection. During my studies I have developed a forma mentis that allows me to quantitatively solve (or try, at least) any issue. Since I was always fascinated by water, hydrology was my ideal choice. I must also say that my professors played a key role: their enthusiasm and passion overwhelmed me, involving me in such a fascinating subject.

At this year’s General Assembly, you will receive the Outstanding Early Career Scientists Award in the Hydrological Sciences Division for your contributions to understanding of the relationship between river environments and human activities. Could you tell us more about your research in this field and its importance?

River discharge has always been my main research focus. During the last 10 years, I had the unique opportunity to focus on the possible implications of river discharge .

Human activities, such as dam development, deforestation, agriculture, urbanization, etc. are known to affect how much flowing water is available to river ecosystems. In particular, I realised that no one before had conducted a quantitative analysis of how human-derived modifications to the natural flow of a river could possibly affect its environment.

Flume experimental facilities. (Photo Credits: Serena Ceola)

During my PhD, I performed an experiment by building small artificial rivers aimed at quantitatively estimating how

stream algae and macroinvertebrates respond to two flow regimes, one influenced by human activity and one unaffected. The unaffected river regime was naturally variable while the other was constant, like downstream a dam.

The experimental results were promising, thus allowing me to develop an analytical model capable of reproducing observed biological data in a real river network, also proving its applicability in presence of anthropogenic influence.

Hydrologic controls on basin-scale distribution of benthic invertebrates: study area and average habitat suitability values for a mayfly species. Image redrawn from Ceola et al., 2014, WRR, https://doi.org/10.1002/2013WR015112

When focusing on human activities, it is extremely important to estimate the interrelations between humans and waters. Here, I was lucky enough to start working with satellite data measuring the distribution of human population in space and time across the globe. By using satellite nightlight images, I analysed the spatial and temporal evolution of human presence close to streams and river. When considering extreme events like floods, I also had the opportunity to identify the regions most at risk for flood deaths and damage to infrastructure.

At the General Assembly, you plan to give a talk about working with global high-resolution datasets, such as nightlight data, to better understand how human and water systems affect each other. What are some of the possibilities made available through this kind of analysis? What doors does this research open, so to speak?

Working with global high-resolution datasets, and in particular with datasets covering several years, allows one to analyse and inspect how human processes and hydrological processes have evolved and interacted in time. This kind of analysis offers the opportunity to study how human pressure on river flows has changed over time and examine urbanization processes influenced for instance by proximity to rivers. This method also allows researchers to analyze how people move as a consequence of climatic conditions, such as extreme floods or droughts.

Spatial evolution of human presence close to stream and rivers by using satellite nightlight images. Image taken from Ceola et al., 2015, WRR, https://doi.org/10.1002/2015WR017482

Before I let you go, what are some of the biggest lessons you have learned so far as a researcher? What advice would you impart to aspiring scientists?

Based on my experience so far my first recommendation is “Be passionate!” Since you will spend a lot of time (days and nights) on a research project, it is fundamental that you love what you are doing. Although sometimes it is difficult and you cannot see any positive outcome, be bold and keep working on your ideas. Then, search for data to support your ideas and scientific achievements (although sometimes it is quite challenging and time-consuming!), but this proves that your research ideas are correct. Interact with colleagues, ask them if your ideas are reasonable and create your research network. Finally, work and collaborate with inspiring colleagues, who guide and support your research activities (I had and still have the pleasure to work with fantastic mentoring people)!

Interview by Olivia Trani, EGU Communications Officer

Imaggeo on Mondays: In-tents Icelandic sunset

Imaggeo on Mondays: In-tents Icelandic sunset

This photograph was taken at the campsite near lake Mỳvatn during a field trip to Iceland. Every year a group of students from Wageningen University travels from the Netherlands to Iceland for a weeklong excursion as part of a course on catchment hydrology. The aim of the trip is to provide students with real life examples of the processes they learned during their lectures.

After a rainy morning that day, tents and equipment were packed away as quickly as possible in order to escape the wetness. The drive took the group from the campsite in Höfn, at the foot of the Vatnajökull glacier in southeastern Iceland, along the coastal highway up north towards Myvatn. Iceland is famous for its raw and beautiful nature, with waterfalls seemingly around every corner and the imposing presence of the glaciers and volcanos in the distance.

Upon our arrival at the campsite in the evening, people begrudgingly noticed that the tents were still wet from the morning rain. The campsite was situated at the bottom of a formidable hill, which provided stunning views over the lake and landscape. Not wanting to sleep in a damp tent, a few students picked up their tents, dismantled them, went up the hill and let the evening breeze do the rest, all amid the backdrop of a stunning sunset. The desire for dry covers even outweighed the very real danger of being eaten alive by masses of midges, a known pest and hazard in these parts.

When camping there is always things that can go wrong. But for places like Iceland it is the only way to truly appreciate and experience the country’s stunning beauty and wilderness. Gazing up at the northern lights from your sleeping bag is a once-in-a-lifetime experience. While waking up in the middle of the night and having to put on boots and jacket to run to the bathroom is vexing, you might be rewarded with views of the top of the glacier that has been shrouded in clouds all day, making it seem like Zeus himself is taking a peek down from Mount Olympus to see what is going on. Iceland has to be experienced, not from a cosy hotel bed, but from a tent put up in the evening and taken down the next day. As Albert Einstein once said: “Look deep into nature, and then you will understand everything better”. Even if that means hiking up a hill and holding your tent up into the wind to dry.

By Maria Warter, PhD student at Cardiff University

 

Geosciences Column: How climate change put a damper on the Maya civilisation

Geosciences Column: How climate change put a damper on the Maya civilisation

More than 4,000 years ago, when the Great Pyramid of Giza and Stonehenge were being built, the Maya civilisation emerged in Central America. The indigenous group prospered for thousands of years until its fall in the 13th century (potentially due to severe drought). However, thousands of years before this collapse, severely soggy conditions lasting for many centuries likely inhibited the civilisation’s development, according to a recent study published in EGU’s open access journal Climate of the Past.

During their most productive era, often referred to as the Classic period (300-800 CE), Maya communities had established a complex civilisation, with a network of highly populated cities, large-scale infrastructure, a thriving agricultural system and an advanced understanding in mathematics and astronomy. However, in their early days, dating back to at least 2600 BCE, the Maya people were largely mobile hunter-gatherers, hunting, fishing and foraging across the lowlands.

Around 1000 BCE, some Maya communities had started to transition away from their nomadic lifestyles, and instead were moving towards establishing more sedentary societies, building small villages and relying more heavily on cultivating crops for their sustenance. However, experts suggest that agricultural practices didn’t gain momentum until 400 BCE, raising the question as to why Maya development was delayed for so many centuries.

By analysing two new palaeo-precipitation records, Kees Nooren, lead author of the study and a researcher at Utrecht University in the Netherlands, and his colleagues were able to gain insight into the environmental conditions during this pivotal time, and the impact that climate change could have had on the Maya society.

To determine the regional climate conditions during this period of time, the authors examined a beach ridge plain in the Mexican state of Tabasco, off the Gulf of Mexico, which contains a long-term record of ridge elevation changes for much of the late Holocene. Since precipitation has a large influence on the elevation of this beach ridge, this record is a good indicator of how much rainfall and flooding may have occurred during Maya settlement.

A large part of the central Maya lowlands (outlined with a black dashed line) is drained by the Usumacinta (Us.) River (a). During the Pre-Classic period this river was the main supplier of sand contributing to the formation of the extensive beach ridge plain at the Gulf of Mexico coast (b). Periods of low rainfall result in low river discharges and are associated with relatively elevated beach ridges. Taken from Nooren, K et al., 2018

Additionally, the researchers also assessed core samples taken from Lake Tuspan, a shallow body of water in northern Guatemala that is situated within the Central Maya Lowlands. Because the lake receives its water almost exclusively from a small section of the region (770 square kilometres), its sediment layers provide a good record of rainfall on a very local scale.

The image on p. 74 of the Dresden Codex depicts a torrential downpour probably associated with a destructive flood (Thompson, 1972). Taken from Nooren, K et al., 2018

The research team’s analysis suggested that, starting around 1000-850 BCE, the region shifted from a relatively dry climate, to a wetter environment. Such conditions would have made a farming in this region more difficult and less appealing compared to foraging and hunting. The researchers suggest that this change in climate could be one of the reasons why Maya agricultural development was at a standstill for such a long time.

The researchers also propose that this long-term climate trend could have been brought on by a shift of the Intertropical Convergence Zone (ITCZ), a region near the equator where northeast and southeast winds intermingle and where most of the Earth’s rain makes landfall. The position of this zone can move naturally in response to Earth’s changes in insolation, and a northerly shift of the ITCZ could help account for some of the morphological changes the authors observed in the precipitation records.

After more than 450 years of excessive rainfall and large floods, the records then suggest that the region experienced drier conditions once again. By this time period, the Maya populations began to rapidly intensify their farming efforts and develop major cities, further suggesting that the wet conditions may have helped delay such efforts.

This is not the first time the Nooren and his colleagues have found evidence of major environmental influence on the Maya civilisation. For example, earlier research led by Nooren suggests that, in the 6th century, the El Chichón volcano in southern Mexico released massive amounts of sulfur into the stratosphere, triggering global climate change that likely contributed to a ‘dark age’ in Maya history for several decades. During this time, often referred to as the “Maya Hiatus,’ Maya societies experienced stagnation, increased warfare and political unrest. The research results were presented at the 2016 General Assembly and later published in Geology.

The results of these studies highlight how changes in our climate have greatly influenced communities and at times even shaped the course of societal history, both for better and for worse.

By Olivia Trani, EGU Communications Officer

References

Ebert, C. et al.: Regional response to drought during the formation and decline of Preclassic Maya societies. Quaternary Science Reviews 173:211-235, 2017

Nooren, K., Hoek, W. Z., Dermody, B. J., Galop, D., Metcalfe, S., Islebe, G., and Middelkoop, H.: Climate impact on the development of Pre-Classic Maya civilization. Clim. Past, 14, 1253-1273, 2018

Nooren, K.: Holocene evolution of the Tabasco delta – Mexico : impact of climate, volcanism and humans. Utrecht University Repository (Dissertation). 2017

Nooren, K. et al.: Explosive eruption of El Chichón volcano (Mexico) disrupted 6th century Maya civilization and contributed to global cooling, Geology, 45, 175-178, 2016

Press conference: Volcanoes, climate changes and droughts: civilisational resilience and collapse. European Geosciences Union General Assembly 2016

Caltech Climate Dynamics Group, Why does the ITCZ shift and how? 2016

GeoTalk: Nilay Dogulu, Early Career Scientist Representative

GeoTalk: Nilay Dogulu, Early Career Scientist Representative

In addition to the usual GeoTalk interviews, where we highlight the work and achievements of early career researchers, this month we’ll also introduce one of the Division early career scientist representatives (ECS). They are responsible for ensuring that the voice of EGU ECS membership is heard. From organising short courses during the General Assembly, through to running and attending regular ECS representative meetings, their tasks in this role are varied. Their role is entirely voluntary and they are all active members of their research community, so we’ll also be touching on their scientific work during the interview.

Today we are talking to Nilay Dogulu, ECS representative for the Hydrological Sciences (HS) Division and past chair of the Young Hydrologic Society.

Before we get stuck in, could you introduce yourself and tell us a little more about yourself, your involvement with EGU and how you became interested in hydrology?

I am a PhD candidate at the Middle East Technical University (METU) in Ankara, Turkey, researching clustering methods for data-driven hydrology at the Water Resources Laboratory. This year I attended the General Assembly (GA) in Vienna for the fifth time in a row. Since 2014, the Assembly has been the one and only conference that I have persistently and willingly participated in. The Hydrological Sciences (HS) division’s scientific programme at the GA had a special role in shaping my career as a researcher, so I would like to share my journey in the hydrological sciences lightened up by the EGU GA and its HS community.

First, little about me. I am a civil engineer by training. I was a third year (BSc) student at METU (ODTU) when I took the course “Engineering Hydrology.” It was the first time I learned about the terms catchment, basin and hydrograph. In that very semester I had the opportunity to participate in the 5th World Water Forum in Istanbul. That was it. I was determined to specialize in water for my future career.

To broaden my understanding of hydrological processes and gain a critical view of the latest hydrology topics, I gathered the courage—as only a BSc student at the time—to attend the 6th National Hydrology Congress and the 2nd National Flood Symposium. Then a three-month internship at the State Hydraulic Works of Turkey introduced me to the wider community of hydrological sciences in the world.

My class notes from the Engineering Hydrology course back in March 2009 (Credit: Nilay Dogulu)

In Fall 2011, I joined the FLOODRisk Master to study floods, from modelling them to understanding their socio-economic effects. This two-years programme enriched my academic background on flood risk management and provided me with different insights into water-related problems.

Could you tell me about your first experience with the EGU General Assembly?

With EGU HS Division president Elena Toth (right) and president-elect Maria-Helena Ramos (left) at EGU 2018

The EGU GA brings together researchers from all around the world. The EGU Hydrological Sciences Division is EGU’s largest division with a diverse and comprehensive scientific programme at the GA, large enough to fill in the whole second (red) floor of the conference venue.

The EGU HS division is a great platform aimed at addressing current research challenges in hydrology. During the GA, one can follow up with the latest research on various topics within these areas and network with members (of all stages) of this great community. At the 2018 EGU GA, hydrological sciences programme had 2350 abstracts submitted to 91 HS-lead sessions (66 oral and poster sessions, 6 poster only sessions, 19 PICO sessions)—equivalent to 13.5% of total EGU GA submissions.

Given this, I was very motivated to experience the General Assembly for the first time! I submitted an abstract summarizing part of my MSc research—on predictive uncertainty estimation for flood forecasting using data-driven modelling techniques; and once it was accepted, I started to get ready for EGU and Vienna! Flight and accommodation booked, poster printed, weekly conference schedule prepared. This was the first poster presentation of my career and I was quite excited. Luckily, all went really well.

EGU Hydrological Sciences Division

I remember having a busy week at EGU 2014: from presenting my first poster, working on a manuscript with my co-authors, as well as attending project meetings, sessions on flood forecasting and flood risk management, and short courses organized by the Young Hydrologic Society (YHS).

There were many interested people visiting my poster and asking questions. There were many posters I visited too—I have to admit, sometimes I asked so many questions that the presenters thought  I was an OSPP Award judge.

Throughout the week I listened presentations, many of which were given by researchers I cited in my master’s thesis. Matching the papers with authors’ faces was amazingly so much fun! Moreover, I arranged a small meeting with my co-authors to discuss the manuscript draft (which has been later published in HESS) that we had only been working on remotely before then.

At the time, I was also working for the EU-FP7 project ASTARTE (Assessment, STrategy And Risk Reduction for Tsunamis in Europe). The EGU GA is an excellent time for research project teams, editorial boards of journals, etc. to schedule meetings.  ASTARTE team (26 partners from 16 countries) also took this opportunity to meet up to discuss the progress following the project’s first 6-months period. During this meeting, I presented one of the very important deliverables of the project which focused on tsunami resilience from a social sciences perspective.

On the Saturday after the conference there was the Vienna Catchment Science Symposium organized by the Vienna University of Technology Centre for Water Resources Systems. It proved to be a very enlightening symposium for a young hydrologist.

Sounds like a great first experience! How has your time at the GA changed over the years?

After enjoying the academic fun of EGU 2014, I wanted to come back to Vienna for EGU 2015. Another reason was that I was very curious why people were heading to the conference venue on the very last hours of the last day (Friday): I left around 5 pm and many people were coming out of metro!

METU Water Resources Lab researchers at EGU 2016

In 2015 I had one PICO presentation and two short course convenerships, How to write (and publish) a scientific paper in hydrology and Hydroinformatics for Hydrology. Both were co-organized with the Young Hydrologic Society and proved to be very successful!

Without any hesitation, I decided to attend EGU 2016 and EGU 2017 in the next years. Although I didn’t have any presentations in 2016, listening to presentations covering my research interests helped me stay updated and synthesise various perspectives on overarching problems in hydrology. The sessions kept me thinking about some questions that had been tingling my mind—which later became the research questions in my PhD thesis proposal.

At EGU 2017, my poster presentation was a literature review on application of clustering methods in hydrology, and actually it attracted more people than I expected. EGU poster sessions provide an excellent way to bring together early career researchers while they stand in front of their posters, paving the way for interesting discussions.

Memories from EGU 2017

My fifth year at the EGU GA last April was great too: including two posters, sessions to co-/convene, YHS events (from short courses to PICO sessions), the EGU ECS Representatives Workshop, YHS Hydrodrinks, the HS division meeting, medal lectures and many other activities. Being an experienced EGU GA participant, I also served as a mentor as part of the EGU mentoring programme designed to help novice conference attendees navigate their first EGU experience.

Almost forgot! On Friday evening, the conveners’ reception (and party, with a different theme every year) takes place at the ACV.

In addition to being an EGU ECS representative, you also are involved with the Young Hydrologic Society (YHS). Could you tell me more about this organisation and your role in YHS?

YHS is a bottom-up initiative that aims to help early career hydrologists interact and actively participate within the hydrological sciences community and beyond. We are a group of motivated PhDs and postdocs who enjoy serving our very own community, considering the needs and interests of young hydrologists.

The YHS is most actively involved with the EGU GA, where we organizing short courses, scientific sessions and social events. The full list of all events that YHS has organized for the EGU GA since 2013 can be found on the YHS webpage. The open call for session proposals for EGU GA 2019 has just closed (deadline 6 September) – there have been quite a number short course submissions (in cooperation with YHS) that will play a significant role in shaping the HS programme for ECSs. YHS Hydrodrinks event held annually at the EGU GA is now a 5-year-old tradition where we meet our new team members. If you are planning to come to EGU 2019, don’t miss the chance to meet fellow hydrologists at the Hydrodrinks (however, please note that this is not a sponsored event). Contributing to the academic and social development of early career hydrologists by organising activities at the EGU GA is a unique and rewarding experience, so get involved!

YHS Hydrodrinks at EGU 2014 (Credit: The waiter)

I joined YHS after meeting the team at EGU 2014. Since then I couldn’t help myself but contribute to the aims of the society in many ways—like organizing short courses at conferences (e.g. Hydroinformatics for Hydrology at the EGU GA), managing and contributing to the YHS Blog (Streams of Thought and Hallway Conversations), and acting as a Board member (secretary 2015-16, chair 2016-17).

Right: EGU 2018 Poster 1—Clustering approaches for analysing similarity in ungauged catchments: input variable selection for hydrological predictions Left: EGU 2018 Poster 2—Input variable selection for hydrological predictions in ungauged catchments: with or without clustering? Bottom Centre: YHS team at EGU 2018 (with only a few missing! It is not east to arrange a common time for everyone, even for a group photo)

I also took over the role of EGU ECS Rep for HS division from Shaun Harrigan at EGU 2017. Being elected as the EGU ECS Rep, I became more enthusiastic about advancing the hydrologic science community equally (and globally) in support of, primarily, the ECS. The ECS Rep is expected to contribute to sustainable and inclusive growth of the EGU HS division by fostering the active participation and integration of ECS and the hydrologic science community globally under the umbrella of EGU, keeping in mind the necessity of creating equal opportunities for ECS to enhance their research and communication skills.

EGU ECS Reps at the EGU GA 2018

The ECS Rep for HS division works in close collaboration with YHS to initiate and support inspirational and intelligent ideas in line with the emerging needs of ECS. You also meet with ECS Reps of other EGU divisions and help the EGU community thrive together with its early career members. My term ends in April 2019. So keep your eye on EGU and YHS websites (and twitter) in early 2019—and apply to become the next EGU ECS Representative (April 2019-April 2021) for the HS division!

Do you have any parting words about your time involved with EGU?

It has been a very long post but now here are the last words. The EGU GA means seeing old friends and past professors, meeting fellow hydrologists and listening to presentations from enthusiastic researchers… plus the annual Hydrodrinks event among many other scientific sessions and short courses organized by YHS! I am glad to serve as the EGU ECS Rep for the Hydrological Sciences division – for the wonderful and inspiring people of the red floor:)

Acknowledgements: I would like to express my sincere thanks to Young Hydrologic Society, especially to Wouter Berghuijs, Shaun Harrigan, Hannes Müller and Tim van Emmerik, for their enthusiasm and support over the last five years.

Interview by Olivia Trani, EGU Communications Officer