Blog – Page 3 – Coastally Curious

Keeping it Connected Around the World

It has been a crazy year, but work-wise I am on the final stretch, at least. Tonight at the ungodly hour of 12am CET, I will present my poster at the American Geophysical Union conference. It is at a much more reasonable 3pm PST in California where the conference organizers are located. If you have registered for the conference, you can see the poster via this link. Otherwise, I will try to put you in the loop here.

Estuaries are complex environments shaped by the interaction of waves, tides, rivers, and humans. Understanding how sand and mud move through estuaries is essential for their effective management. In an approach known as connectivity, the pathways taken by sand and mud through estuaries can be represented as a connected network of nodes and links, similarly to a subway map. Connectivity provides numerous mathematical techniques and metrics that are well-suited to describing and comparing these pathways in estuaries.

Network diagrams depict the sediment transport pathways of each estuary as a series of nodes and connecting links. The Mouth of the Columbia River (1) and San Francisco Bay (2) are on the west coast of the United States, while Ameland Inlet (3) and the Western Scheldt (4) are in the Netherlands. Red arrows indicate the 90th percentile of all connections in terms of sediment fluxes, superimposed on greyscale bathymetry of each estuary.

We use connectivity to map out and analyze sand and mud pathways in four estuaries around the world: the Wadden Sea (the Netherlands), Western Scheldt (NL), San Francisco Bay (US), and Columbia River (US). Our analysis is based on the outcome of numerical simulations, and we explore the benefits of different simulation techniques. We conclude that connectivity is a useful approach for visualizing and comparing the pathways that sand and mud takes through different estuaries. We can use this method to plan and predict the impact of human interventions in these environments, such as dredging.

However, a comparison of connectivity metrics suggests a dependency not just on sediment transport processes, but also on the choices made in schematizing networks from underlying models. Essentially, we’re not comparing apples to apples yet, so if we are going to make comparisons between different estuaries, we need to make sure that we set up our models in an equivalent way. Our ongoing research will focus on optimizing these numerical models to make more meaningful quantitative comparisons of different estuaries.

Keeping our feet dry and safe from the big water with lots of tiny rocks!

Some ideas are really hard to understand, but it helps if we can talk about them using simple words. One of my favourite books of all time is the Thing Explainer by Randall Munroe, the cartoonist behind XKCD. In it, Munroe tries to describe scientific concepts using only the 1000 most common words in the English language. With the help of a text editor to flag any illegal words, I prepared the following summary of my PhD research, and am presenting it tomorrow in a special science education session at the online American Geophysical Union conference. If you are not attending, you can also check out my presentation here:

Here are the words that go with my pictures:

There is a very low land next to the big water. It has a lot of wind and it rains there most of the time. It is so low that it would be under water now if people didn’t build big walls around it and suck all the water out. The big water is going up and up and up, and we want to keep everyone’s feet dry so that they stay safe for a long time to come. The plan is to put lots and lots of very tiny rocks along the edge between the big water and the very low land. When there is too much wind, the big water will make huge waves. These will hurt the wall of very tiny rocks, but if we have enough very tiny rocks, the big water won’t get inside the very low land and the people will be safe. It is hard to guess where these very tiny rocks will go when we put them on the edge of the big water, because the waves move them around. We use water-counters, rock-counters, and computers to learn more about how the very tiny rocks move through the water and make better guesses about what they will do. People in many other lands are also worried about huge waves and the big water going up, so we hope that the things we learn in the very low land can help them too.

This was one of the most fun presentations I have ever made, and it changed the way I think about my research. After all, if I can’t explain what I’m doing, the dissertation I have spent five years writing will just collect dust on a bookshelf instead of contributing something useful to the world.

But perhaps even more importantly for the fulfillment of my muppet-loving childhood dreams, it meant being able to legitimately refer to “the big blue wet thing” at a Serious Scientific Conference.

The Side Effects of Trying to Keep Our Feet Dry

In an era of rising sea levels, ambitious plans for coastal protection works are emerging around the world. One such plan is the Delta21 project, proposed by group of Dutch coastal engineers and entrepreneurs. Their goal is to improve flood protection at the mouth of the Haringvliet estuary and develop a tidal power facility, all in one integrated project.

However, the law of unintended consequences often looms large in these sorts of massive infrastructure projects, particularly for environments as complex as estuaries. After a massive flood in 1953, the Dutch constructed the Delta Works, damming most of the estuaries in the southern half of the Netherlands. Prior to that, the Afsluitdijk was constructed across the Zuiderzee in the northern part of the country. These protection works have had dramatic consequences on the physical and ecological development of the Dutch coast, and many of my colleagues here have devoted their careers to analyzing the impact of these interventions.

But instead of just looking back and dissecting the successes and failures of 50 or 100 years past, what if we could also use our latest diagnostic tools for predicting the potential impact of bold future interventions? If the Delta21 plan goes ahead, how will the mouth and ebb-tidal delta of the Haringvliet estuary and surrounding coastline evolve? Will existing habitats (particularly in vital intertidal areas) be preserved, disappear, or even expand?

Today, Mayra Zaldivar Piña tackled these questions head on, and successfully defended her master’s thesis, “Stability of intertidal and subtidal areas after Delta21 plan“. I had the pleasure of co-supervising Mayra’s work throughout the last eight or so months, and am very proud of her. She embarked on a challenging modelling project and showed an exemplary critical scientific attitude. I was also so impressed with the persistence and tenacity she showed in doing nearly her entire project during the pandemic. Writing your thesis is a difficult and isolating experience at the best of times, and these are not the best of times. Nonetheless, she kept at it and delivered an impressive thesis in the end!

Congratulations Mayra, and best of luck in the next steps of your career!

Sediment Connectivity: Where does all the sand go?

I am thrilled beyond measure to announce that the first paper of my forthcoming PhD dissertation, Sediment Connectivity: A Framework for Analyzing Coastal Sediment Transport Pathways, has finally been published (open-access) in the Journal of Geophysical Research: Earth Surface!

What’s it about? As sand moves along coasts and through estuaries, the pathways it takes are determined by a complex combination of waves, tides, geology, and other environmental or human factors. These pathways are hard to analyze and predict using existing approaches, so we turn to the concept of connectivity.

What is connectivity? Connectivity represents the pathways that sediment takes as a series of nodes and links, much like in a subway or metro map (see here for a primer). This approach is well used in other scientific fields like neurology, oceanography, and fluvial geomorphology, but in our study we apply these techniques to coastal sediment dynamics.

So what? To show how the sediment connectivity approach can be used in practice, we map sediment pathways with it at Ameland Inlet, an estuary in the Netherlands. The statistics we compute using connectivity let us quantify and visualize these sediment pathways, which tells us new things about the coastal system. We can also use this approach to answer practical engineering questions, such as where to place sand nourishments for coastal protection. We hope to use sediment connectivity to predict the response of our coasts to climate change, and the human adaptations that these changes provoke.

**A conceptual summary of our paper on sediment connectivity at Ameland Inlet in the Netherlands.** **(a,c)** We can schematize the sediment transport pathways in an estuary as a series of nodes (A,B,C,…) and the links connecting them. **(b)** This network can in turn be represented by a matrix, showing where the sediment is coming from (a source) and where it’s going to (a receptor). In this form, we can investigate questions like, “where does the sand in node F go?” **(d)**, or “where does the sediment reaching node D come from?”**(f)**. In my research, we are most interested in answering questions like, “what is the main pathway between the two islands, node A and G?” **(e)**. We can also learn how the system is organized into “communities” that share sand **(g)**, and how that changes when pathways are added or removed **(h)**.

It has been a long journey, beginning with The Magical Figure that Changed My Entire PhD and now culminating in this publication. I am especially indebted to my supervisors, Bram van Prooijen and Zheng Bing Wang, for their constant support. I am also grateful to my other co-authors, Edwin Elias from Deltares and Sean Vitousek at USGS, for seeing potential in this approach and really strengthening and clarifying my story. I was also blessed with curious and constructive reviewers who provided a much-needed non-engineering perspective on our work.

Now that this paper is out, the fun can really begin! I have lots of fun ideas for applying connectivity to other estuaries around the world including the Mouth of the Columbia River and San Francisco Bay. We are also in the process of developing new modelling tools that well help us better unravel how estuaries and coasts are connected. Stay tuned!

Sources:

Pearson, S.G., van Prooijen, B.C., Elias, E.P.L, Vitousek, S., & Wang, Z.B. (2020). Sediment Connectivity: A Framework for Analyzing Coastal Sediment Transport Pathways. Journal of Geophysical Research: Earth Surface. [Link]

Ameland Datapalooza!

Check out our new paper here!

Three years ago, I experienced one of the highlights of my professional career so far. Alongside researchers from 3 universities, the Dutch government, and several other institutions, we carried out a 40-day field measurement campaign at Ameland Inlet in the north of the Netherlands. We deployed several frames loaded up like Christmas trees with every instrument imaginable: ADVs and ADCPs to measure waves and currents, LISSTs and OBSs to measure suspended sediment, a YSI multiprobe to measure salinity and other water quality indicators, and even a 3D sonar to track the migration of ripples along the seabed.

One of the five measurement frames that we deployed in Ameland back in Fall 2017. It was stacked full of instruments to measure the waves, currents, suspended sand and mud, salinity, ripples, and more.

Four of our five frames survived the relentless ebb and flow of the tide, and even two major storms (one of which left me stranded in Germany after the wind blew down all the overhead train power lines between Berlin and Amsterdam!). In the end, we obtained enough data to keep me busy for probably 3 PhDs, if not the rest of my career. This is just as well, since that last frame was buried in the storm, and based on our understanding of the local dynamics, it will likely re-emerge in another few decades, just in time for my retirement! I look forward to sharing my other findings with you here in the next few months!

Although it used to be the norm for scientists to squirrel away their data, there is an increasing movement towards open accessibility of research data. This improves transparency and accountability in the scientific process, and opens up new opportunities for collaboration. The data we collected is now available in its entirety here on the 4TU web portal or on Rijkswaterstaat’s interactive web viewer.

However, there is a lot of data – I mean A LOT! To help researchers interpret the contents of this database, we prepared an overview paper, which was finally published in the journal of Earth System Science Data! It is also accompanied by a more detailed report, which gets into the nitty-gritty details we didn’t have room to describe in the paper. Nobody likes to read a phonebook-sized report, but it’s nice to have the information there for the few brave souls who do want to comb through our dataset.

Sailing across the Vlie ebb-tidal delta on our way to retrieve the measurement frames at the end of the field campaign.

It was all a huge team effort, as evidenced by the 20+ co-authors. My contribution to this paper focused on the processing of the LISST and YSI multiprobe data, which tell us about the size of particles floating through the water, and how salty that water is. I also designed the maps. As a kid, I loved to read and draw maps, and I think that 7-year-old Stuart would have been tickled to know that he would still be dabbling in cartography all these years later.

As the research in the rest of my PhD (and beyond!) will continue to focus on the fruits of this measurement campaign, I am very keen to work together and collaborate with other researchers who have an interest in this dataset. Please get in touch if you are interested!

Rolling the Dice: Dealing with Uncertainty in Coastal Flood Predictions for Small Island Developing States

Small island developing states around the world are especially vulnerable to the hazards posed by sea level rise and climate change. As engineers, we have a number of tools in our toolbox for reducing the risk posed by coastal flooding and for planning adaptation measures. We often rely on predictive models which combine information about expected wave and sea level conditions, the topography of the coast, and vulnerable buildings and population to estimate potential flooding and expected damage.

However, to use these types of models, we first need to answer a lot of questions: what exactly are the expected wave and sea level conditions? What if detailed topographic measurements are unavailable? What if the population of a given coastal area increases? How are the local buildings constructed, and what are the consequences of that for estimating damage from flooding?

If our information is imperfect (which it almost always is), all is not lost: we can still make educated guesses or test the sensitivity of our models to a range of values. However, these uncertainties can multiply out of control rather quickly, so we need to be able to quantify them. There is no sense in spending the time to develop a detailed hydrodynamic model if your bathymetry data is crap. Can we get a better handle on which variables are the most important to quantify properly? Can we prioritize which data is the most important to collect? This would help us make better predictions, and to make better use of scarce resources (data collection is expensive, especially on remote islands!).

Matteo Parodi investigated these questions in his master’s thesis, and just published his first paper, “Uncertainties in coastal flood risk assessments in small island developing states“. I had the great privilege and joy of co-supervising Matteo during his thesis, and I am immensely proud of him and his work!

Based on a study of the islands of São Tomé and Príncipe, off the coast of Africa, Matteo found that topographic measurements and the relationship between flood depth and damage to buildings were the biggest uncertainties for predicting present-day flood damage. This means that measuring topography of vulnerable coastal areas in high resolution, and performing better post-disaster damage surveys will provide the best “bang for your buck” right now. However, for longer time horizons (i.e. the year 2100), uncertainty in sea level rise estimates become most important.

Matteo’s work will help coastal managers on vulnerable islands to better prioritize limited financial resources, and will improve the trustworthiness of our predictive models. Great job, Matteo!

Can 3D-Printed Corals Help Us Prevent Flooding?

Coral reefs around the world are dying; that much is clear from the headlines we see in the news that grow increasingly distressed with each passing year. This is an ecological catastrophe, but are we also losing another key benefit of reefs? Coral reefs provide a form of natural protection against wave-driven flooding on tropical coastlines. This is partly because the physical form of the reef (often a big rocky shelf) serves as a sort of natural breakwater, but is also due to the frictional effects of the corals themselves.

Many species of coral have complex shapes that disrupt the flow of water across reefs, generating turbulence and dissipating energy. This has the effect of reducing the height of waves as they travel across the reef towards the shore. However, these effects are incredibly complex and poorly understood, so we usually just simplify them in our predictive models by considering a reef to be more “hydraulically rough” than a sandy beach, for example. But we need to do better: these models are used to forecast flooding and estimate the impact of future climate change on vulnerable coasts.

How can we improve this? In coastal engineering, we often conduct experiments in the laboratory to test our theories and understand the chaos of natural systems in more controlled settings. What if we could make a scale model of a coral reef and measure exactly how waves are dissipated?

I am extremely proud to announce the graduation of Paul van Wiechen, one of the Master’s students whom I have had the pleasure of supervising. Yesterday, he defended his thesis, “Wave dissipation on a complex coral reef: An experimental study“, where he built a tiny coral reef in the TU Delft wave flume (a 30-m long bathtub with a wave-making paddle at one end) using hundreds of 3D-printed coral models.

Paul’s thesis, “Wave dissipation on a complex coral reef: An experimental study“.

It was one of the coolest projects I have ever seen, and his research provides us with valuable measurements that give us a deeper understanding of the vital role that corals play in protecting our coasts.

He also did all of this in the middle of a global pandemic, and somehow managed to stay completely on schedule. We are very lucky, because Paul will be joining the Coastal Engineering department here at TU Delft to start a PhD on dune erosion this fall. We are all glad to have him on the team and eager to see what his research unveils next!

Clustering Coral Reefs for Coastal Flood Forecasting

Many of the world’s idyllic tropical coasts are facing threats on multiple fronts. Rising seas threaten the very habitability of many low-lying islands, and the coral reefs that often defend these coasts from wave attack are dying, too. Compounding this problem is the sheer number and variety of these islands: there are thousands of islands, and the coral reefs surrounding them come in all shapes and sizes. Located around the globe, these islands are each exposed to a unique wave climate and range of sea level conditions. This variability in reef characteristics and hydrodynamic forcing makes it a big challenge to forecast how waves will respond when they approach the shore, something that is quite tricky even at the best of times. Under these circumstances, how can we protect vulnerable coastal communities on coral reef coasts from wave-driven flooding?

This is the problem that our fantastic former student, Fred Scott (now at Baird & Associates in Canada), tackled in his paper, Hydro-Morphological Characterization of Coral Reefs for Wave Runup Prediction, recently published in Frontiers in Marine Science. Working in partnership with Deltares and the US Geological Survey for his master’s thesis, Fred came up with a new methodology for forecasting how waves transform in response to variations in the shape and size of coral reefs.

fredFigure1 — **(A)** This is a typical fringing coral reef cross-section, showing waves approaching from the right, with the shore on the left. **(B)** Fred came up with a number of algorithms for classifying and organizing the massive dataset of coral reef cross-sections. **(C)** The measurements used in our study are from sites around the globe. **(D)** This is what 30,000 reef cross-sections look like when you try to plot them all on top of one another- clearly we need to whittle those down a bit… [Source: Scott et al, 2020]

In our previous research on this topic, we tried to predict flooding on coral reef-lined coasts using a very simplified coral reef shape. This was fine as a first guess, but most reefs are bumpy and jagged and bear little resemblance to the unnaturally straight lines in my model. We couldn’t help it though: there just wasn’t enough data available when I started my thesis four years ago, so we did the best we could with the information we had at the time. On the bright side, using a single simple reef shape meant that we could easily run our computer simulations hundreds of thousands of times to represent a wide range of wave and relative sea level conditions.

Fast forward three years to when Fred began his own thesis. We now had access to a mind-boggling dataset of over 30,000 measured coral reef cross-sections from locations around the world! However, instead of too little data, we now had too much! If we wanted to simulate a whole range of wave and sea level conditions on each of the reefs in our dataset, it might take months or even years to run our models! Fred had the daunting task of distilling that gargantuan database down to a more manageable number of reef cross-sections.

But how do we choose which cross-sections are the most useful or important to look at? Even though every coral reef is, like a beautiful snowflake, utterly unique, surely there must be some general trends or similarities that we can identify, right? This question lies at the heart of Fred’s research, and to answer it, he turned to many of the same powerful statistical and machine-learning techniques used by the likes of Google and Facebook to harvest your life’s secrets from the internet or power self-driving cars. Maybe we can use some of this technology for good, after all!

The main approach that Fred used in this study was cluster analysis, a family of techniques that look for similarities or differences between entries in a dataset, and then group the entries accordingly into clusters. The entries within one cluster should be more similar to each other than to the entries in other clusters. In our case, this meant grouping the reefs into clusters by similar shape and size. This allowed us to increase efficiency and reduce redundancy by proceeding with 500 representative cross sections, instead of the entire database of 30,000.

zoom — These days when I’m lonely, I Zoom with 500 of my favourite coral reef profiles…

Other studies in our field have tried similar approaches (such as this Brazilian study of coral reef shape), but the innovative part of Fred’s technique was to also account for similarities in the hydrodynamic response of the waves to each reef via a second round of clustering. Wave transformation on coral reefs can be immensely complicated, so it is entirely possible that two reef profiles could look very different, but lead to the same amount of flooding in the end. Since we are mainly concerned about the flooding (rather than a classification for ecological or geological purposes about coral reef formation and evolution), this suits us just fine!

In the end, Fred was able to distill this colossal dataset into between 50-312 representative cross sections that can forecast wave runup with a mean error of only about 10%, compared to predictions made using the actual cross sections. This opens the door wide for a range of future applications, such as climate change impact assessments or coral reef restoration projects. Right now, we are working on a new project that will apply Fred’s approach to the development of a simplified global early-warning system for wave-induced flooding on coral reef-fronted coasts.

Great work, Fred, and congratulations on your first publication! I am excited to see where this road takes us!

Sources:

Scott, F., Antolinez, J.A.A., McCall, R.C., Storlazzi, C.D., Reniers, A.J.H.M., & Pearson, S.G. (2020). Hydro-morphological characterization of coral reefs for wave-runup prediction. Frontiers in Marine Science. [Link]
Scott, F. (2019). Data reduction techniques of coral reef morphology and hydrodynamics for use in wave runup prediction. [Link]. TU Delft MSc thesis in cooperation with Deltares and the US Geological Survey.
Scott, F., Antolinez, J.A., McCall, R.T., Storlazzi, C.D., Reniers, A., and Pearson, S., 2020, Coral reef profiles for wave-runup prediction: U.S. Geological Survey data release [Link].

Betty the Resilient

Today we say goodbye to my Grandma, the inestimable Betty Pearson. Although its effects on my life have been quite tangible, the coronavirus remained quite abstract: something defined more by an absence of things than by a presence. Sadly, my grandmother has joined the ranks of those taken down by this great absence. Another absence that my family keenly feels right now is our own: her funeral this afternoon will be attended by my uncle and a few of my cousins, but my dad and the rest of my family are scattered across Canada and Europe. We cannot attend the ceremony in Scotland, since although our world has stopped for a moment, the pandemic outside just keeps on rolling.

But I hardly think that Grandma’s life should be upstaged by current events, so today I want to shine a light on this remarkable woman, the most resilient person I ever met. Grandma was a woman of incredible strength, courage, and love. Born in Scotland in 1925, she spent the better part of her teenage years in the Second World War, probably the sort of experience that makes you grow up too quickly. After the war, she moved to Canada to start anew.

On the ship across the Atlantic, she met some folks who were on their way to visit some friends in Richmond Hill. Grandma stayed in touch with them, and she was later introduced to the family whom her shipmates were staying with. She got wind that they were going bowling, and their son came to pick her up. “I thought he was alright! IMMEDIATELY! I’ll always remember. He was wearing a white v-neck sweater, and he was very kind.” This was Bun (Bernard), our Grandpa, a dashing young pilot. By 1953, they were married, and had spent several years moving around the country as his job took him to different air bases. It was in Alberta that my Dad appeared, and a few years later in Ontario, my Uncle Glenn. During these years, Grandpa took many journeys across the high Arctic islands of Canada, as part of mission to map these remote northern territories.

Tragedy struck in 1961, when my Grandpa died in a helicopter crash in remote Labrador. After that, she moved back to Scotland to raise her boys closer to her parents, first living in Largs, and then Glasgow. In spite of such an immense personal loss, she brought up Dad and Glenn in a very loving home, something for which she will have my eternal gratitude. Under the sort of circumstances that would have easily derailed lesser souls, she persisted. Grandma went back to school to become a teacher, and eventually worked her way up to became headmistress of a school in Glasgow. In spite of the tragedy that they endured at a young age, her two boys did not just get by, they thrived, getting good educations and building successful careers for themselves. Most importantly, they built loving families of their own. In all of these things, but especially the latter, Grandma was extremely proud of her boys. The love and strength that she brought to the world in the face of great challenges was undoubtedly an important factor in them turning out so well.

She went from Mum to Grandma when I came along in 1989, followed shortly thereafter by my three cousins, my brother, and my sister. Even though we grew up on the other side of the Atlantic from her, she always made the effort to get to know us and see us at least once a year, usually at Christmas. She was always full of love and encouragement. Also chocolate and books.

The latter was particularly important for me: at Christmas 1997, Grandma gave me a book that had been winning rave reviews in the UK, but had yet to make much of a splash in Canada. Telling the wonderful story of a young wizard and his friends, this book proved to be a gift that would keep on giving, launching an obsession that would continue into – let’s face it – my 30s. Harry Potter still brings me great joy, and has brought me closer to friends from around the world who share that same joy. Thanks, Grandma.

In 2006, just before my final year of high school, I was privileged to spend the summer in Scotland, hiking in the highlands and hanging out with her in Glasgow. This was the start of getting to know her as more than just a child. She started to change in my eyes, becoming more than just the wonderful woman who appeared at Christmas to dispense excellent hugs and heaps of books. I began to understand the incredible life she had lived, and how much that had shaped my family and my own life.

My relationship with Grandma began a new when I moved to Europe to start my master’s degree in 2014. I lost my other grandparents in 2008 and 2011, but unfortunately never really got to know them well as an adult. I was determined to make the most of things and get to know Grandma. Furthermore, after 2014, I was the nearest member of our immediate family, so I felt that seeing her was a small way of bringing us all closer together. Glasgow is a cheap 1.5 hr flight from Amsterdam, so I made as many trips as I could, going once or twice a year since I moved out here.

During one of my busier semesters, I gave her a call to see if she wanted to chat. “How about Tuesday? I have bridge club right now!” My then-90-year-old Grandma had a more exciting social life than I did, but that was pretty much par for the course – she was always the life of any party she attended. At her local mall, the salespeople all knew her by name, famous for making her rounds with friends or the occasional grandchild in tow. Until well into her 90s, she possessed extraordinary reserves of energy, taking three flights of stairs every day to get up and down from her elevatorless apartment. I hope that I have that much get-up-and-go when I am that age.

Grandma was also elegant and full of class, always comporting herself with the utmost dignity when we went out. In spite of this demeanour, or maybe even partly because of it, she also had another side that gleefully embraced the ridiculous. One Christmas morning, she waltzed (in a manner of speaking) down the stairs wearing a truly ostentatious Christmas sweater and pigtailed hat, looking like some sort of ludicrous viking elf. She then proceeded to yodel, even though, I am sad to say, yodelling was not one of her many gifts. Whenever we visited the Kelvingrove gallery in Glasgow, I always insisted that we visit the Elvis statue. Grandma would unfailingly oblige me, joining in on the bizarre photoshoots I would instigate with her and The King.

What did we do together when I came up to Glasgow? Truthfully, not much, but it never mattered. We would often sit in front of the TV together, eating fish and chips, or getting up to date on the latest gossip about so-and-so’s husband from downstairs. Determined that running up and down hills in Norway had made me too skinny, she also passed considerable time trying to convince me to put more butter on my toast. We always tried to get out of the house too, whether it was driving down the coast to Largs for a ludicrously extravagant ice cream (her favourite), rolling around Kelvingrove park, or just going for a spin around the mall.

Her apartment in Glasgow will always be one of my Happy Places. The view from her window, the old trinkets on her shelves, and the creak of her floorboards are immensely calming. Last year, Grandma moved into a retirement home, and even though she slowed down a lot, she always seemed to have more sparkle in her eyes than anyone else in there. Grandma was always supportive and full of love, and I was happy that even as her memory started to fail, she still remembered me and enjoyed our time together.

In recent visits, she would often remark to me, with a mix of sadness and pride, “I’m a survivor”. And she was! She made it to 94, living a life full of love in spite of the immense challenges that she faced over the years. I will miss her immensely, but am comforted by all of the good memories and positive things, of which there are many. I love you, Grandma.

Flood Hazards on Vulnerable Atolls

How can we predict flooding on vulnerable atolls in the Pacific? Today, Tije Bakker defended his thesis, entitled “Compound flood hazard assessment of atoll islands based on representative scenarios for typhoons and non-typhoon conditions: A Majuro case study“. Tije is one of the master’s students that I supervise, and we are all proud of him and his work.

Majuro is an atoll island in the Marshall Islands, located in the middle of the Pacific, just north of the equator. With 20,000 people packed into less than 10 square kilometres, it is one of the most densely-populated islands on earth. It is also in big trouble: with an average elevation of only 3 m above sea level, Majuro faces serious risks of flooding. They can’t “head for the hills”, because there are none. The threat of drowning under rising seas looms on the horizon, but many low-lying tropical islands like Majuro will be rendered uninhabitable not within centuries but within mere decades due to flooding by waves.

Predicting these floods and planning appropriate measures to mitigate their impact is thus a matter of life or death for people living on these islands. My previous work on this topic considered only “sunny day” floods due swell waves generated by distant storms. Tije’s thesis took the next step and focused specifically on predicting compound floods: the combined effects of flooding due to waves and rain. On top of that, Tije took on the much more challenging task of predicting the massive and volatile typhoons that can clobber a small island like Majuro.

The methods he developed will be very useful not just for Majuro, but also for other vulnerable islands. Given its relevance and novelty, we hope to publish it as a paper in the coming months. Great job, Tije!