Jaime Martindale, map and geospatial data librarian at the Arthur A. Robinson Map Library. Image: Bryce Richter, Journal Sentinal
When a patron requested information about a military plane that had crashed in Wisconsin during World War II, she started, as the article says, digging into the records. The crash site had been well-known at one time, but had not been marked. Tom Sybert wanted to honor the Air Force pilot and crew, and wisely reached out to a library when Google proved inadequate. The article describes Martindale's deft use of multiple sources to re-find the site, and Sybert can now work on his plans for a memorial.
The USDA photos she used were a big part of my early work in geography. They were taken from the bottom of aircraft that would cris-cross the country for the purpose, flying in parallel paths over few years to make photographs for soil surveys. Active farming areas got photographed more often. The photographs overlapped by 60 percent so that any one place was photographed twice from different angles -- allowing for stereo pairs that could allow 3-D viewing.
I used them in my master's thesis research to map land uses in my study area and to measure ponds. I used them in environmental consulting to help build timelines of the properties we were researching -- many city and town sites were included because it was simplest just to keep the paths continuous. The photos continue to be archived in depository libraries such as the Robinson collection and are now available through a USDA web site.
From the article I learned a couple of interesting things about the geographer for whom UW-Madison's map library is named. I know him mainly as the inventor of a map projection that is a favorite among geographers -- the Robinson Projection. In representing a (nearly) spherical earth on flat maps, all projections make compromises among fidelity in distance, area, shape, and direction. No projection is "more accurate" than others, but they serve different purposes more or less effectively. The compromise achieved by Robinson is a favorite for representing patterns of human activity at a world-wide scale.
My favorite librarian and I are currently reading a book about another kind of library hero -- The Bad-Ass Librarians of Timbuktu. Watch this space for our commentaries on the book. Timbuktu is a real place, and its librarians are worthy of the book's title!
From Todd Zwillich on The Takeaway, I just learned that today is the silver anniversary of one event of global importance, and the gold anniversary of another. Both are cause for celebration and contemplation on the part of a a geographer who spends a lot of time reading and writing about the big picture online.
The image is grainy, but it was a sobering reminder that all we have and all we are -- all of our conflicts and all of their resolutions -- are contained in a thin layer on a rather small mass of rock hurtling through space.
A quarter century later, on August 23, 1991, this web page -- which had been created a couple weeks earlier -- became available outside of the CERN network, a day now known as Internaut Day. I was not aware of the details at the time, but as someone who used campus networks in the late 1990s and were using networks such as gopher with crude search tools such as Archie, Veronica, and Jughead, we (my fellow graduate students, librarian wife, and I) were delighted to learn about the concept of hyperlinking pages. The idea of finding resources that we did not already know about was intriguing. Even though I helped to launch one of the first commercial food sites a few years later, I could not have guessed what the Web would be like these billions of pages later.
In the late 1990s, a friend with a strong interest in theology introduced me to the work of Teilhard de Chardin, a theologian whose prescient work explored the connections between today's landmark anniversaries -- well before either had taken place. (Note: it has been more than a decade since I updated the page linked above.)
MIA (Maya Arulpragasam) was a refugee before politicians used them for fear-mongering. Her status as a Tamil refugee (in the UK from Sri Lanka) has always been a part of her public identity, and so she was well prepared to address the current tendency to re-victimize those fleeing war zones. As the world has more internally and externally displaced persons than it ever has, her work is addressing the political treatment of refugees directly. I was thinking of this work as I wrote my recent post, One in a Thousand, about refugees from Syria who many think are "flooding" the United States.
Her slickly-produced yet eerie track Borders is the most important example. It not only depicts refugees, it employs them directly in the work -- not only as migrants but also as representations of the migrant vessels themselves. With this work, she challenges not only the ways in which people are treated when they cross borders, but also the purposes of the borders themselves. Not only do they separate people from each other, but increasingly they also serve as a kind of sieve that separates the work of people from the humanity of the very same individuals. In other words, people on the "wrong" side of a border are able to provide their labor, but not to exercise civil or human rights.
As she asks throughout the piece, "What's up with that?" In his cogent analysis of the piece, geographer Sinthujan Varatharajah explains that this refrain is addressed specifically at "hashtag activism." One might even extend the critique to mere blogging, but I do think we have a duty to use whatever tools we have to challenge complacent thinking about borders.
Lagniappe (Sept 12, 2016)
MIA has a new album -- MIA -- which she recently discussed with David Greene on NPR's Morning Edition. Among other topics, she talks about her surprising (to some) life as a middle-aged parent. More importantly, she talks about her evolving views on race in a global context.
Lagniappe-squared (August 9, 2019)
From Marketplace comes reporting that further dispels common misconceptions of refugees as singularly burdensome.
The story highlights experiences and research in the UK, but is especially relevant in the United States, where a shockingly xenophobic administration is resorting to desperate and inhumane measures to ensure that refugees cannot even approach our borders.
Lagniappe^3 (last one, I promise, but this is really relevant)
This still image from Adrian Paci's 2007 video, Centro di permanenza temporanea (Temporary Detention Center) evokes some of the imagery used by M.I.A. Perhaps she was influenced by this work.
I am often amazed by the ability of good radio journalists to conjure visual imagery. In the case of recent reporting by Susan Stamberg (one of the very best), her words (listen below) drove me to the screen to explore photos from an exhibit she visited recently. I wish I had heard this before my recent visit to the area -- the exhibit is in D.C. only through September 22, 2019.
Most affected, of course, has been Baton Rouge, a city already reeling from shootings by police and shootings of police earlier in the summer. As Emma Brown writes for the Washington Post, the flooding -- though devastating -- is reminding Louisianans that above all, they can and do rely on one another. The sacrifice of public-safety and medical teams as well as ordinary residents on behalf of each other has been nothing short of heroic.
The so-called Cajun Navy supplements the efforts of rescue and
restoration by local, state, and federal agencies.
It is not clear when, but at some time after these waters recede, a serious discussion must be had about the new maps of Louisiana. This week's flood -- called a 1,000-year event -- will certainly be reprised before another thousand years passes.
Lagniappe (a Louisiana term for a little something extra)
Randy Newman's version of Louisiana 1927 is included in my 2011 post about Old River Control. My Climate Attack post in February of this year was mainly about the Pacific islands of Kiribati, but it included a reference to permanent evacuations from the Gulf Coast. Finally, my Houston-New Orleans post of just two weeks ago highlights resistance to long-term thinking about rising waters and sinking lands.
And what's the opposite of Lagniappe (i.e., a little less)?
The laboratory of the Louisiana Universities Marine Consortium is located in the midst of that disappearing land. It is a place where those researching rising seas experienced severe flooding at work 75 times last year. It is one of dozens of such research facilities that are endangered by the very phenomena they were established to study, according to reporting by NPR coastal journalist Tegan Wendland.
In the summer of 2000, I made my second visit to Brazil, and the first visit with my family. We had spent the night in a small hotel in the center of Porto Velho, and my friend Miguel was driving us to his house on the edge of the city, where I had spent three months in 1996. I will never forget his words to Pam as we made our way through the sometimes bumpy roads of the city: "Excuse me, I live on the periphery of the periphery of the periphery."
Miguel is a literary scholar, but he has a keen grasp of geography as well. His first periphery refers to Brazil's position as a zone of extraction in Wallerstein's world-system model. His second periphery is Rondônia's position on the edge of that country -- both in terms of its physical location and in terms of the domination of extractive industries there. Later in the visit, in fact, the president of the Brazilian Studies Association -- meeting for the first time in Brazil itself -- was amazed that I had been to Rondônia, and breathlessly told me, "It's very frontier!" Miguel's third periphery was simply his gradually-improving neighborhood at the edge of the capital city. (One night many years later, I would be scrolling through the neighborhood in Google Earth and noticed that the street in front of Miguel's house -- my old street -- seemed to have been paved. I was able to confirm this with him right away on Facebook.)
The edge of Cidade Lobo, as seen during my 1996 visit.
I spent much of that 2000 visit surveying residents of yet another periphery -- Cidade Novo (New City), which I had found at the very edge of the city four years earlier. I had gone to Cidade Lobo (Wolf City, after a man named Lobo who had owned the land), trying to understand the growth of the capital city. As I stood with Cidade Lobo behind me, I took this photo -- the first house in what was being called Cidade Lobo II.
Four years later, it was a bustling neighborhood, and I took two of Miguel's students with me to survey the new residents -- where had they come from and why, I wanted to know. I almost stopped asking the first question, "Why did you come here?" because I got the same answer every time: Para melhorar a vida. To improve my life. And indeed this nascent favela was a refuge for several different kinds of settlers: people who had abandoned rural settlements (who were the main subject of my dissertation), people who were seeking refuge from the noise and crime of downtown Porto Velho (this surprised me), and people migrating directly from favelas in São Paulo (2,000 miles away, half of it along the infamous BR-364, which was more of an extended series of potholes than an actual road). This last group welcomed the chance to buy (informally) a plot measuring 10x30 meters (33x100 feet), as São Paulo offered only 10x5-meter plots, at best.
This all came to mind this morning as I read about an unmapped neighborhood on the western edges of Nairobi, Kenya. A small thing I had noticed about Cidade Novo is that the houses were numbered, but not in any particular order. People simply posted numbers that they liked, until such time as the municipality and post office would assign formal addresses. In Porto Velho -- as in much of Latin America -- the process of in-situ accretion would lead almost inevitably to such gradual improvements, so that this neighborhood would eventually resemble that in which Miguel and my other academic and professional friends were living.
Author (and mariner and amateur geographer) Olivier Le Carrer describes the Nairobi exurb of Kibera in his captivating Atlas of Cursed Places: A Travel Guide to Dangerous and Frightful Destinations. He describes its growth from a reasonably-populated settlement of a few thousand people spread over two square miles a few decades ago, to an uncharted settlement of half a million people in the same space, making it one of the most crowded and least governed places on earth.
Le Carrer offers a glimmer of hope, however, in the form of a cadre of geographers. Yes, geographic skills are what Kibera needs most desperately, and the Map Kibera project is bringing them to Kibera and a few other communities, putting -- as its website exclaims -- marginalized communities on the map! The importance of empowering people through open-source mapping technologies was recognized, in fact, during a recent White House Mapathon, in which Map Kibera participated.
Despite common perceptions to the contrary, scarcely 1 person in a 1,000 displaced from Syria reaches the United. States. Those who do arrive rely on the kindness of neighbors for assistance during what will be the most difficult transition of their lives.
Najla, a Syrian refugee cooking for other refugees at
Global Grace Café in Highland Park, New Jersey.
Photo: Deborah Amos/NPR
A recent profile of one such community discusses the motivation of those who offer help and highlights the humanity -- as if it were in any doubt -- of the people who have fled the crumbling Assad regime. One of the longest-established, accomplished civilizations on the planet has unraveled, pushing millions out of their homes. The chaos that ensued when people organized against the tyrant Assad created an opening for terrorists,which in turn created an opportunity for Vladimir Putin to step in on behalf of his despotic ally.
I should be clear -- I am not suggesting that the U.S. should take in all the refugees or even a large proportion of them. And the individual communities -- such as those shown above -- who are directly supporting them deserve a lot of credit for doing so.
Most who flee Syria are living in neighboring countries. Map: UNHCR, Aug 2016
But the we suffer from serious misconceptions the scale of refugee resettlement. I have even heard it suggested that neighboring countries should be doing more -- despite the fact that six neighboring countries already ARE hosting most of the refugees, with most of the rest going to Europe.
Omran Daqneesh, sits in an ambulance Wednesday in Aleppo, Syria.
Image: Mahmoud Raslan/Anadolu Agency/Getty Images
Among the heroes who remain in Syria are those who operate hospitals and ambulances as the skies fall around them, and as hospitals themselves have become targets. At a time when many in the United States and Europe have come to fear victims of this devastation as much as the perpetrators comes a gripping reminder of just what is at stake -- the stunned silence of Omran Daqueesh has captured imaginations as few other victims have. Update: The BBC reported on August 20 that Omram's ten-year-old brother Ali has now died, like far too many before him, and far too many to come.
Climate change is real. It is happening every day in our country, on every continent and it is affecting all walks of life. The article in the Sierra Magazine online entitled, “DirtbagSnowboarders Rescue our Climate” (Jan/Feb 2016) tells the story of how even the simplest pleasure of skiing is being affected by warming temperatures. But the main point in the article describes how even the smallest, unlikeliest group of people can bring awareness and make a difference.
Bolivia once had a ski area called Chacaltaya. It was built in 1939 and boasted a 17,000 foot ski mountain. According to many who had the great pleasure of skiing there, it was amazing. By 2009, the snow cover of the mountain was gone, melted. The same is happening everywhere to other ski areas both large and small. This article states that over 80% of the U.S ski resorts rely on artificial snow to keep their slopes open. It also predicts that in 30 years up to half of those resorts could close due to warmer winters.
Jeremy Jones, who is a professional snowboarder and actor, began looking for a climate group to donate to. When he could not find what he was looking for, he founded his own in 2007. He named it Protect Our Winters, or POW for short. In 2012 POW partnered with Natural Resources Defense Council (NRDC) and issued a report that stated the ski industry lost $1.7 billion to low-snow years.
Although Jones and his colleagues had never been to the White House and knew nothing about lobbying or law-making, they were passionate enough about this cause to give it a try. They quickly got the attention of Capitol Hill because now climate change was affected the economy at the ski resorts. Another big benefit of their organization was that it also brought awareness to a younger generation, which is always a good thing. POW has now partnered with the National Ski Area Association and Snow Industries America to further its cause.
Extreme skier POW board member Chris Davenport at Revelstoke Mountain Resort, British Columbia.
Photo: Christian Pondella, Sierra Magazine
This article proves that the idea of one can bring thousands together in order to make a change. I enjoyed this article because it gave a positive spin on an otherwise negative topic. After reading Carl Safina’s book (The View from Lazy Point) and this article, the concept of climate change is starting to make sense to me. When Safina visited Alaska he talked about the concrete proof that was proved beyond a shadow of doubt that our glaciers are shrinking and disappearing. Safina and the POW may have different reasons for bringing awareness of climate change, yet their commonality of protecting the world for now and the future resonates to everyone.
from James Hayes-Bohanan:
Amanda Pace was a student in the online version of an introductory course that shares its name with this blog: Environmental Geography. For the past several years, students have read the Carl Safina text she mentions above. For almost twenty years, students in this course have been asked to browse Sierra and to choose one article that they can connect to the themes of the course.
This essay does so particularly well, and I asked for Amanda to participate as a guest blogger because it resonates so well with other materials on this blog -- which include several posts about Carl Safina's work and more importantly the several articles I have posted about Cochabamba (a city in highland Bolivia) as a site that is at the forefront of conflict over climate and water. Frankly, as much thought as I have given to the snows of Bolivia, I never thought of it as a ski area until I read this essay.
One final note from me: the organizers of POW were wise to involve the snow-sports industry. If there were climate-change deniers in that industry before, there most certainly are none now.
Who knew that on the edge of the Bronx is a small island full of multi-generational family homes and small marinas, connected to the rest of the city only by a single, low bridge?
I certainly did not, until we watched a quirky 2006 film bearing its name: City Island. It stars Andy Garcia as a correctional officer who commutes from a house his grandfather built to a prison in Westchester County. He brings home an inmate who initially introduces more secrecy and dysfunction into an already complicated family dynamic.
Each member of the family is easy to dislike, and throughout the film they hardly seem to like each other. But the banter is as clever as it is cruel, and the various threads of discord are eventually tempered as they are brought into the open.
I wish we had known about the film last year, when we were frequently in the area because our daughter was attending Sarah Lawrence in Bronxville. We enjoyed getting to know Yonkers and Bronxville, and would have enjoyed exploring this little corner of the Bronx itself. We will definitely find our way there some time in the near future.
I also wish that the film had spent just a bit more time in the neighborhood. The audience is told about the importance of this place to the characters -- especially to the "Clam Digger" local played by Andy Garcia. He does describe it as a little-known square mile of the city (it is closer to 1/3 of a square mile) and the film does include some nice "windshield surveys" as characters drive around avoiding each other.
But aside from the unusual friendship that develops between the family's teenage boy and some female neighbors, we see little of the other people in the community. This was especially surprising during the climactic family showdown that takes place outside of the home, without a single neighbor becoming involved.
The film's official trailer gives away a few too many punchlines, so instead of watching below, I recommend finding the whole film on Netflix (sorry, DVD only at this point).
The cities shown here -- with apologies for Google's deplorable use of the U.S.-centric version of the Mercator projection -- are featured in a recent article by Mark Herman, simply entitled Thirsty Yet?
A greatly reduced Thames is just one of the changes to which urban dwellers may need to adjust.
Based on the United Nations World Water Development Report, the article is a reminder that the perils of climate change vary considerably from place to place. While much of our focus is on rising seas caused by the thermal expansion of the upper layer of ocean water and the melting of ice stored above sea level, lack of fresh water is an equally serious risk, and in some cases will be a problem in the very same places affected by sea-level rise.
More broadly, the article reminds us that environmental problems operate at varying scales and interact with each other in complicated ways.
A few years ago, a colleague described her dismay when she learned that many of her undergraduate students did not know about tides. Most of them grew up within a few miles of the ocean, yet many did not realize that the seas rise and fall by a few feet twice each day. It was not that they were uncertain of the details; they really had no idea that tides are a thing.
One of the benefits of taking up rowing whaleboats has been that my own understanding and awareness of the coastal environment has greatly increased. I have started paying much closer attention to wind speed and direction, for example, and have learned some of the patterns of movement of other boats.
Yet the more I have learned about tides, the more I find I do not know. The harbor where we do most of our rowing is at the mouth of the Acushnet River -- where a small stream merges with the Atlantic Ocean. The interaction of currents and tides is complicated, and very important for understanding the behavior of our boats!
As I started to look into the relationship between tides and currents, I found that NOAA's maintains a series of FAQ pages on just that subject. I was particularly interested in the relationship between high and low tides and slack tides.
NOAA also offers a basic primer on tides -- Our Restless Tides methodically explains all of the factors that influence the timing and elevation of tides, from the sun and the moon to the orbits and declinations of each, as well as the shape of the ocean floor and the viscosity of water itself. It is fascinating to me that anybody understands all of these factors in as much detail as the folks at NOAA clearly do. They even know how much time is needed to develop a reliable record of tides in order to make local predictions: 18.6 years. Not 15, not 20, but 18.6!
All of which brings me to this map. The two markers -- less than 8 miles apart -- are located near the points where tides are calculated for the east and west ends of the Cape Cod Canal -- the world's largest sea-level canal (no locks). The locations are not precise -- the coordinates given on US Harbors are actually nearby points on land, but the locations are fine for making the point at this scale.
And the point is that since the entire canal is at sea level, water does not flow from one end to the other. In fact, prior to the canal's construction, small streams flowed from a point somewhere in the middle downward toward what are now the endpoints.
Several years ago, I was at the U.S. Army Corps of Engineers visitor center on the canal, where a former student happened to be a ranger. (Actually, the COE operates two visitors centers -- the one on the southeast side has more maritime information and navigational toys.) I asked him why the tide charts showed very different times at the two ends of the canal. The main reason has to do with sea floor topography, and the differences are so great in this area because the continental shelf is so much wider on the east side than on the west, and tides are affected as they cross this relatively shallow water.
The differences can be seen on today's (August 7, 2016) tidal chart as rendered by U.S. Harbors, a handy site for coastal information.
I have long been curious about the two rivers (mentioned above) that were joined to create the Cape Cod Canal. As mentioned in the history section of the Cape Cod Canal entry on Wikipedia, these were the Manomet and Scusset Rivers -- indigenous names that are still used in other features in the region. I finally got curious enough to seek out a map!
I chose to show this 1891 map because it shows a very early segment of the Canal at the eastern end, but both rivers largely still intact. It is part of a series of maps depicting the area from 1753 (when the Manomet was called Herring Run on English maps) through 1917, when the Canal was complete.
Lagniappe -- Coffee Connection
It turns out that all of this is relevant to my favorite subject: coffee. My friend Byron was already known for making the best coffee in the world (literally: he won a world-wide Cup of Excellence) when he decided to involve the moon in his coffee production. Like most coffee experts, he was already carefully managing the sunlight on his shade-grown coffee, but he wondered if the moon's influence on water inside the coffee plant could in turn influence flavor. By concentrating sugars in the fruit, it turns out, it could do exactly this. Now his family is among the first to market specialty coffee to domestic retail customers in Nicaragua, and they call it Sol y Luna: Sun and Moon!
Although I love driving with music, whenever I am driving alone I am more likely to be listening to public radio. During a recent drive, I heard most of an excellent hour of journalism about urban planning, and it put me in mind of this great piece of driving music.
The reporting was an in-depth examination of urban planning and disaster preparedness in the great Texas city of Houston, which Jerry Garcia found to be "too close to New Orleans."
I am not quite sure what he ever meant by the line ... maybe he just meant the 350 mile stretch of Interstate 10 that joins the two cities. I was thinking, though, more abstractly ... about hurricane stories with eerie parallels.
The feature article begins with a narrative describing the hurricane's aftermath as if it had actually occurred. I remember reading it with students in my climate change class a year later -- and it took a while for them to realize I was not reading an account of Hurricane Katrina, a very real storm that had struck New Orleans in August 2005.
In other words, a lot of what happened to New Orleans not only could have been predicted; much of it was predicted. Which brings us to Houston, a decade later. Houston should be especially sensitive to hurricanes. Not only has this coastal city had plenty of its own experiences over the past century or more, but it received many refugees from New Orleans during Katrina.
So Houstoniansshould be eager to prepare for future hurricanes, and some of its leaders are indeed working on serious preparations for what is called a Mighty Ike hurricane. In this case, the real hurricane came first. Hurricane Ike struck Haiti, Cuba, Louisiana, and Texas, costing many billions of dollars and killing close to 200 people (some were never found), but a shift in its path spared Houston the worst of the damage, and gave planners there a bit of a second chance.
The planning and recommendations for what was dubbed Mighty Ike have provided an extensive case study of disaster preparation more generally. Interactions among population growth, construction patterns, transportation networks, and climate change are complex and have played out in this planning process. It is the subject of a one-hour report by Reveal News that serves as a primer on the environmental geography of hurricane preparation.
One segment of the reporting focuses on the dangers posed by tank farms -- the large storage tanks associated with the petroleum and chemical industries that are so important in Houston. A small sample is shown here, in the Bayshore area.
Each circle is a tank, perhaps 150 feet in diameter and 30 to 50 feet high. Each is surrounded by a square berm that provides secondary containment in case of a rupture in the tank or a leak in its piping. In my former life as a regulator analyst, I would sometimes have to calculate the required height of such berms -- it was usually just a few feet. (Yes, I put my high-school math to work in the real world.)
Right after hearing the Houston story, I found a kitchen-scale analogy while draining cold-brew coffee with a Filtron brewer. I placed a high-rimmed plate under the decanter, just in case I had too much water (which I did not). As with the berms around the giant tanks, a relatively modest rim provides all the needed containment -- which is based on the amount of storage in the tank or in the coffee maker. These regulations were never intended to protect the tanks from water coming in, just as my plate is not designed to protect from a wave crashing across the kitchen counter. The problem, of course, is that these tanks are far more likely to encounter a tidal surge than my coffee is to catch a rogue wave. The containment berms need to be re-conceived as exclusion berms or -- as the story indicates -- these huge tubs of poison can simply float away.
The report also serves as a reminder of all the ways in which humans will resist uncomfortable news about the environment, and will certainly resist spending money to prevent or mitigate disaster. Geographers and other experts now tend to avoid the phrase "natural disaster," in fact, because choices made by humans so often shape the outcome of catastrophic events (not necessarily for the same humans).
Lagniappe -- A Third City
It was not just Houston and New Orleans that were brought to mind by this reporting. The Might Ike story was updated for radio a year after its original broadcast, but I heard it just a day or so after a localized but devastating storm struck one of my favorite places -- Ellicott City Maryland. I have posted about this twice so far -- Flood Flash and Flood Peak -- and may be adding a third post, as I think about the Might Ike scenario and as I read local critics who recognize the connections between Main Street flooding and the construction of houses and shopping areas in the headwaters.
Details are not available, but this image suggests the hydrological connections between the flood zone on Main Street and the increasing replacement of forest with impervious surfaces in the headwaters.
UPDATE (added March 2020, in reference to 2017 and 2019 events)
Sadly, Houston did get.a chance to experience the kind of problems in the Might Ike exercise, and it was not good. Hurricane Harvey in 2017 and Tropical Depression Imelda in 2019 did tremendous harm to the city. As Kate Yoder wrote for Grist, the latter storm -- which dropped 40 inches of rain in one event -- might lead to the disappearance of the dismissive phrase "not even hurricane" from local language.
On the night of the storm, I saw a short
video in which this clock
was ripped from its base.
Thanks to social media, I continue to watch news from Ellicott City, Maryland. It is a charming little town that I visit every time I return to Maryland; a couple days ago, I posted about the most recent flood to ravage the town, just a week after we had enjoyed walking and shopping there. The town has experienced severe floods every decade or two since it was founded. This is the first flood, however, to have taken place in the age of smart phones, and it happened during the Pokemon Go craze, so that even more recordings of the calamity are available than would be otherwise. It also seems likely that even though this was far from the highest flood level experienced in Ellicott City, waters seem to have risen much more rapidly than in prior events.
The small city continues to return, owing to several factors, and in fact some preliminary rebuilding is already underway. The article and video Shop owners search for closure offers some insight into the reasons people will rebuild.
A subsequent article describes the efforts of a local kayaker who has found cars in the river nearby, along with the town's iconic clock tower. He mentions the fact that the nearby Patapsco River floods when flow reaches about 10 times its normal volume. On most rivers, this level -- called bank-full discharge -- could be expected to occur at every 2-3 years.
The flood data mentioned by the kayaker comes from a gage in the main stem of the Patapsco River, just a mile or so downstream from the Main Street, which acted as a tributary of the Patapsco that night. (The mouth of the Patapsco River, incidentally, forms the Baltimore Harbor.
During this week's flood event, flow rates reached 300 times normal, and perhaps 500 times the recent low. Notice the scale on this graph -- it is logarithmic, as are many graphs used by hydrologists. If this graph used a linear scale, the peak flow would be shown somewhere a couple dozen feet above your screen.
The relationship between flow and elevation is unique for each point along any given channel -- it is known as the rating curve. Stream gages actually measure the water's elevation, and then the volume is calculated from that. The night of July 31, the gage surged more than 15 feet above its prior level, and quickly fell back to just a foot or two above that level.
Note that this is these levels were recorded in the main channel of the Patapsco. It represents an averaging of flow over a much larger basin that the small tributary basin where the most intense rainfall occurred. In other words, the flashiness of this event -- had it been measured at the base of Main Street -- would have been even more dramatic than what is shown here.
Maryland photographer David Alton has posted some beautiful, poignant and intriguing photographs of the aftermath, including several that reveal the extent of structural damage. Flowing water is powerful, and its ability to do destructive work increases exponentially with depth. What makes it all the more powerful is that its ability to entrain sand, gravel, cobbles, and even boulders (those are actually technical terms) also increases exponentially. So the rushing water shown in so many social-media videos during the storm was actually like flowing sandpaper, doing this kind of scouring below the surface -- indeed below what used to be the streets and sidewalks. As a fellow geographer in the area pointed out, loose cobblestones were readily available on this street, perhaps adding incrementally to the undermining that occurred.
During the storm, I became aware of the importance of this clock as a symbol of the town. A young man making a short video during the flood commented about the clock as he showed it being pulled away by the rushing water. "There goes the clock," he said almost reverently -- this signified much more than the other objects he could be filming at that moment. It is remarkable that just two days after it was found by the kayaker mentioned above, it was back on its pedestal, helping to restore a sense of place in Ellicott City.