Water Underground

One in four of world’s big cities water-stressed

One in four of world’s big cities water-stressed

From the McGill Newsroom

As more people move to urban areas, cities around the world are experiencing increased water stress and looking for additional water supplies to support their continued grow.

The first global database of urban water sources and stress, published online this week in Global Environmental Change, estimates that cities move 504 billion litres of water a distance of 27,000 kilometers every day. Laid end to end, all those canals and pipes would stretch halfway around the world. While large cities occupy only 1% of the Earth’s land surface, their source watersheds cover 41% of that surface, so the raw water quality of large cities depends on the land use in this much larger area.

An international team of researchers from nine institutions, including McGill University in Montreal, surveyed and mapped the water sources of more than 500 cities, providing the first global look at the water infrastructure that serves the world’s large cities. The study was led by Rob McDonald, senior scientist with the Nature Conservancy in Arlington, Va.

Prof. Bernhard Lehner and PhD student Günther Grill of McGill’s Department of Geography contributed a detailed global map of rivers, lakes and watersheds to help map the water sources of each city, while Prof. Tom Gleeson of McGill’s Department of Civil Engineering conducted analysis for groundwater sources.

The research team used computer models to estimate the water use based on population and types of industry for each city, and defined water-stressed cities as those using at least 40% of the water they have available. Previous estimates of urban water stress were based only on the watershed in which each city was located, but many cities draw heavily on watersheds well beyond their boundaries. In fact, the 20 largest inter-basin transfers in 2010 totaled over 42 billion liters of water per day, enough water to fill 16,800 Olympic-size pools.

There is good news in the findings: Many cities are not as water-stressed as previously thought. Earlier estimates put approximately 40% of cities into the water-stressed category. This analysis has the number at 25%.

The study finds that the 10 largest cities under water stress are Tokyo, Delhi, Mexico City, Shanghai, Beijing, Kolkata, Karachi, Los Angeles, Rio de Janeiro and Moscow. (Neither of the two Canadian cities analyzed — Toronto and Montreal — was water-stressed, according to the definition used in the study.)

The study also makes clear the extent to which financial resources and water resources are intertwined. It is possible for a city to build itself out of water scarcity — either by piping in water from greater and greater distances or by investing in technologies such as desalinization — but many of the fastest growing cities are also economically stressed and will find it difficult to deliver adequate water to residents without international aid and investment.

“Cities, like deep rooted plants, can reach a quite a long distance to acquire the water they need,” says McDonald. “However, the poorest cities find themselves in a real race to build water infrastructure to keep up with the demands of their rapidly growing citizenry.”

The study also reveals that:

  • Four in five (78%) urbanites in large cities, some 1.21 billion people, primarily depend on surface water sources. The remainder depend on groundwater (20%) or, rarely, desalination (2%).
  • The urban water infrastructure of large cities cumulatively supplies 668 billion liters daily. Of this, 504 billion liters daily comes from surface sources, and that water is conveyed over a total distance of 27,000 km.
  • Land use in upstream contributing areas affects the raw water quality and quantity of surface water sources.
  • An estimated one-quarter of large cities in water stress contain $4.8 trillion of economic activity, or 22% of all global economic activity in large cities. This large amount of economic activity in large cities with insecure sources of water emphasizes the importance of sustainable management of these sources, not just for the viability of individual cities but for the global economy.

The research was supported by a grant from the Gordon and Betty Moore Foundation.


“Water on an urban planet: urbanization and the reach of urban water infrastructure,” Robert. I. McDonald, et al, Global Environmental Change, published online June 2, 2014. http://dx.doi.org/10.1016/j.gloenvcha.2014.04.022

Groundwater extraction can move mountains

Groundwater extraction can move mountains

Contributed by Pascal Audet (webpage or email)


Historic 1977 photo of Dr. Joseph Poland, USGS, considered the pioneer of scientific subsidence studies. Dates on telephone pole indicate previous land elevations in an area SW of Mendota. Photo credit: U.S. Geological Survey

Next time you eat food grown in the San Joaquin Valley of California, think about this: the water used for growing them probably came from under ground. Farmers do not really have a choice because the amount of water from rain and snow can’t keep up with the needs for growing food. Every year more water is drawn out of the ground for irrigation. Because of this, the floor of the San Joaquin Valley goes down as the sediments compact once the water is out (see picture on right).

In the latest work from our team, we find a surprising side effect of groundwater pumping: the mountains surrounding the valley (the Sierra Nevada and California Coast Ranges) are moving up a few millimeters each year, as shown by a large number of GPS instruments. This may seem very small to humans, but for hard rocks it is quite fast. We find that this uplift can be explained by the loss of water out of the ground, as shown by gravity data from the GRACE satellite. The water lost through irrigation lowers the weight on the Earth’s crust, which responds by bouncing back up like a spring.

One interesting implication of this study is the impact on earthquakes on the San Andreas Fault. Uplift of the crust (and mountains) decreases the grip on the fault, making it easier to slip and cause small earthquakes during busier times of groundwater pumping. Perhaps more important, our study shows that humans can really move mountains through industrial agriculture. In California, this effect may get worse because more droughts, earlier snowmelt and different rainfall patterns are expected due to climate change.

This article is the second in a series of plain language summaries on Water Underground (link to first). The 5upgoer word processor showed that ~80% of the words in this post are in the 1000 most common words in the English language. For recent news coverage of this article check out this.

What busy profs would like to read in a blog post about active learning

What busy profs would like to read in a blog post about active learning

During a great workshop today on active learning in engineering at McGill I asked two questions (using Socrative) , of the audience. Here is a summary of 24 answers I received:

1) I would like to read blog posts about:

  • activities for large classes (18% of people)
  • activities for small classes (30% of people)
  • technology in active learning (22% of people)
  • wacky or creative ideas for active learning(30% of people)

2) I might read a blog post about teaching and supervision if…

  • It takes into account the sheer lack of time and resources for preparation; ie quick and easy ideas to engage a bored class!
  • it was linked through twitter
  • It was regularly updated and interesting!
  • It does not take too long
  • it helps me achieve better my teaching objectives compared to my current teaching practice
  • It related to economics / social science a bit
  • Its short and introduce tips and examples
  • It gives concrete practical examples of activities for teaching and making students more active
  • I was interested
  • I knew where to find it
  • It dealt with distance education
  • they talked about encouraging creativity and critical thinking
  • it was about new and creative strategies that I can use in my class
  • it included the occasional evidence-based pieces that demonstrate real impact
  • Give ideas about how to get the students more active
  • It’s concrete, thoughtful and provides ideas
  • it was relevant and to the topic. I also would like to see it promoted within the departments to encourage conversation about teaching and learning
  • It is useful

My summary is that people want to hear about all types of different aspects of active learning and they would be motivated to read posts if it interesting and provided something useful.

Thanks Michael Prince of Bucknell for the great workshop and Milwaukee Mag for the image.

Surprises and lessons learned from co-teaching an inter-university graduate course

Surprises and lessons learned from co-teaching an inter-university graduate course

GrantFergusonContributed by Grant Ferguson, University of Saskatchewan


In an earlier blog post, Tom discussed some of the advantages and disadvantages of co-teaching a blended graduate course to students at McGill University, the University of Wisconsin – Madison and the University of Saskatchewan. This course wrapped up last month… we definitely learned a few things during its delivery, some of which were surprises that we hope you can learn from.

Surprise #1: The course outline and structure came together rather quickly and there was minimal debate on the content that we would cover. We did not attempt to be comprehensive in our coverage and chose to teach to our research interests. At the same time, we did not feel that there were obvious gaping holes in the curriculum. We included a review of what we expected the students to understand coming into the course. Although we were teaching students from a variety of backgrounds including civil engineering, environmental science, geosciences and forestry our expectation was that everyone should have been exposed to similar content in their undergraduate hydrogeology course. A recent review on the content of undergraduate hydrogeology courses by Gleeson et al. (2012) indicated that the core content of these courses does not vary that much from university to university.

However, surprise #2: students had very different interests and strengths. Some universities had students that excelled at MatLab while others were far more proficient with GIS. The interests of students also tended to mirror those of their home institutions. Students from McGill tended to be interested in water resource sustainability and large-scale problems, students from Saskatchewan were focused on problems associated with resource-extraction and students from Wisconsin tended to be more interested on hydrological processes and ecosystems. Exposing these biases, strengths and weaknesses was valuable for both instructors and students.

Surprise #3: this may not be a more ‘efficient’ way to teach since we spent far more time preparing lectures for this course than we normally do for other courses. Teaching to students and other universities with other instructors present brought teaching to a different level.   This effectively negated the initial thought that this would be a more efficient way of teaching because we were only on the hook for a third of the lectures. Part of this preparation was related to knowing that we would be forced to rely on slides more heavily than in a conventional classroom. However, the greater motivation was knowing that this presentation was going outside the walls of the home institution and that colleagues from other universities would be following along.

Surprise #4: Communication during the course went more smoothly than expected. Aside from a few momentary hiccups, there were few problems hearing the lecturer. Talking between institutions during the lecture went well, although questions were generally repeated by the lecturer or someone nearer to the microphone at other schools. The biggest obstacle might have been for the lecturers. Despite some efforts to situate cameras and explore different views within Microsoft Lync, it was difficult for the lecture to see the remote classrooms. Without being able to see facial expressions or body lan20140325aguage, it was difficult to assess how the material was being received at the other locations. This problem can likely be resolved to some extent with additional monitors and better cameras.

The feedback from the students was largely positive. Most of them seemed happy to participate in this experiment and get some exposure to other institutions. Tom, Steve and I all agreed that we would do this again given the chance. However, it appears that the stars might not align for us in 2015 due to some other commitments. We will see if we still feel this way in 2016.

Re-posted on Inside Higher Ed blog.

Best groundwater song ever? “Once in a Lifetime” by the Talking Heads?

Best groundwater song ever? “Once in a Lifetime” by the Talking Heads?

Kevin Befus
Contributed by Kevin Befus, University of Austin – Texas

If there has ever been a song for hydrogeologists, “Once in a Lifetime” by the Talking Heads is the best. Here’s why I have taken this song on as my hydrogeologic theme song.

But first, here is a link to the music video, in all of its early 1980’s glory:

Music is great because the listener can interpret the music and lyrics with their biases. My bias in this song is not about the drudgery of life (1) . It is about water which is everywhere in this song, and maybe that means we humans see water as mundane, everywhere and maybe a bit menacing. I fully encourage you to evaluate your life through this song, but let’s get on to the hydrogeology!

Where does this song get the hydrogeology right? I was surprised.
“Water flowing underground” – groundwater moves and is not still (but can be super slow), except maybe in stagnation points that may also be dynamic (2).

“same as it ever was” – groundwater responds over long time scales, but may not always be in the same place (3) . Even still, water is eventually renewed and continues on its many paths through the water cycle, same as it ever was.

“Into the blue again” – back to the ocean, with an average retreat of 4000 yrs (4) ; shout out to the submarine groundwater discharge community (5)!

“After the money’s gone” – water can be something we retreat to as a source of comfort or leisure, but here’s an idea: what do we do with water problems when the money is gone? How do economics affect water resources? Do we turn off the pumps and let water flow to the blue again, L.A. (6)?

“Water dissolving and water removing” – shout out to hydrogeochemists and transport modelers (7) ; yes, you, Chebotarev (8)!

“There is water at the bottom of the ocean…remove the water from the bottom of the ocean” – there sure is, and more than we thought (9)! Maybe a water resource that will be tapped more and more.

“Under the rocks and stones” – well, there is water under rocks and stones, but also inside, brushing but sadly missing porosity and saturation. This doesn’t mean I don’t like this lyric.

“Silent water” – if there is any water on Earth that is silent (and that is unlikely, depending on the definition of what sound is), groundwater would be a good place to imagine a silent water droplet.

The underlying theme of passing time is what really gets me. Once in a lifetime, this water is flowing underground. What a great way to introduce the timescales of groundwater flow! Or, even begin a lesson on groundwater, ranging from basics to interactions at the coast or human impacts? How precious is this water if it can only be replenished once in a lifetime?

May we someday not have to say to ourselves, “my god, what have we done?”

1. http://www.allmusic.com/song/once-in-a-lifetime-mt0011967560
2. Gomez, J. D., and J. L. Wilson (2013), Age distributions and dynamically changing hydrologic systems: Exploring topography-driven flow, Water Resour. Res., 49(3), 1503-1522.
3. Gleeson, T., Y. Wada, M. F. Bierkens, and L. P. van Beek (2012), Water balance of global aquifers revealed by groundwater footprint, Nature, 488(7410), 197-200, doi: 10.1038/nature11295.
4. https://www.e-education.psu.edu/earth540/content/c3_p7.html
5. Burnett, W. C., H. Bokuniewicz, M. Huettel, W. S. Moore, and M. Taniguchi (2003), Groundwater and pore water inputs to the coastal zone, Biogeochemistry, 66(1-2), 3-33, doi: 10.1023/B:BIOG.0000006066.21240.53.
6. http://www.wrd.org/engineering/seawater-intrusion-los-angeles.php
7. http://ponce.sdsu.edu/the_salinity_of_groundwaters.html
8. Chebotarev, I. I. 1955. Metamorphism of natural waters in the crust of weathering. Geochimica et Cosmochimica Acta, Vol. 8, 22-48, 137-170, 198-212
9. Post, V. E. A., J. Groen, H. Kooi, M. Person, S. Ge, and W. M. Edmunds (2013), Offshore fresh groundwater reserves as a global phenomenon, Nature, 504(7478), 71-78, doi: 10.1038/nature12858.

European research vacation 2014

European research vacation 2014

National Lampoon’s European Vacation was one of my favorite movies growing up but I hope it is not what happens over the next few weeks. I am visiting colleagues and giving talks at ETH Zurich, Utrecht University, Gottingen University, and then EGU in Vienna. Four countries in three weeks! I thought it might be useful to list my talks and dates here for people who might be interested…

ETH Zurich – Tuesday April 15

From global groundwater depletion to the sustainable use of groundwater systems

Groundwater—the world’s largest freshwater resource—is critically important for irrigated agriculture and hence for global food security. Yet depletion is widespread in large groundwater systems in both semi-arid and humid regions of the world. Excessive extraction for irrigation where groundwater is slowly renewed is the main cause of the depletion, and climate change has the potential to exacerbate the problem in some regions. Globally aggregated groundwater depletion contributes to sea-level rise, and has accelerated markedly since the mid-twentieth century. But its impacts on water resources are more obvious at the regional scale, for example in agriculturally important parts of India, China and the United States. Food production in such regions can only be made sustainable in the long term if groundwater levels are stabilized. To this end, a transformation is required in how we value, manage and characterize groundwater systems. Technical approaches—such as water diversion, artificial groundwater recharge and efficient irrigation—have failed to balance regional groundwater budgets. They need to be complemented by more comprehensive strategies that are adapted to the specific social, economic, political and environmental settings of each region.

Utrecht University – Tuesday April 22

Multidisciplinary, multi-scale hydrogeology: localized flow around fault zones, shale gas contamination and global groundwater sustainability

Groundwater, the world’s largest freshwater resource is critically important for irrigated agriculture, ecosystems and as a drinking water resource. This talk explores three question at the interface of hydrogeology, structural geology, geochemistry, engineering, geomatics and sustainability science: 1) Do fault zones affect regional groundwater flow? 2) Could hydraulic fracturing lead to contamination of aquifers via faults? And 3) Is global groundwater use sustainable? The first question is examined using radon gas tracers into show that the presence of fault zones does not impact the rate of groundwater discharge to lakes. This suggests that shallow, old faults are hydrologically insignificant in the Appalachian orgogen. The second question uses numerical models to quantify the factors that control contaminant transport potential. We find that long-term contaminant transport from shale gas horizons to shallow aquifers occurs in specific conditions with the most critical factors being the location of the hydrofracturing zone relative to the fault and top of shale, the overpressure of shale and the permeability of the fault zone. The third question uses the newly proposed groundwater footprint to map groundwater stress globally.

Gottingen University – Thursday April 24 (same talk as Utrecht; details here)

Great groundwater video!

Great groundwater video!

Clear graphics, good message and an awesome sing-along. what more could one ask for? the only message that I would add is the importance of virtual groundwater use in what we decide to consume, especially our food.

The importance of groundwater for climate models

The importance of groundwater for climate models


Contributed by Nir Krakauer nkrakauer@ccny.cuny.edu

Does water fall if no one hears it? It does. Invisible water flows slowly under the ground, in soil and rock, downhill or from wet to dry areas. This groundwater eventually surfaces at rivers, springs, swamps, and other water features. As rivers and lakes get tapped out or polluted, more groundwater is being pumped out for irrigation and industrial uses, hurting the animals groundwater flow sustains.[1] Yet we still know little about how far and fast groundwater flows.

In my team’s work, we trace the flow paths of groundwater in two ways. First, we consider the geometry of the paths groundwater must follow from its origin as rainwater and what that implies about the amount of groundwater that typically flows in or out of regions of different sizes. Second, we simulate groundwater flow in each continent based on detailed surface height maps from satellites. We mapped the likely groundwater flow directions and rates under natural conditions (no pumping). With this baseline, we expect to better determine how groundwater pumping impairs water flows and ecosystems.

One implication of this study has to do with how scientists simulate climate. Models run on computers to forecast weather and project climate changes currently ignore groundwater flow pathways. We find that the amount of water conveyed by groundwater flow is significant over path lengths of up to several tens of kilometers. The resolution of global and regional climate models is now becoming good enough to resolve these flow paths, and we are beginning to explore how such groundwater flow affects cloud and rainfall patterns.

This article is the first in a series of plain language summaries on Water Underground. This article and others will be put through the 5upgoer word processor to test for the 1000 most common words in the English language…almost half words in this article that aren’t this list including importance, groundwater and climate… from the title!)

Active learning in large classes: a gallery ‘walk’ with a 100 students

Active learning in large classes: a gallery ‘walk’ with a 100 students

Active learning in large classrooms is difficult but not impossible – here is one example of an active learning technique developed for small classrooms, the gallery walk, which I have successfully re-purposed for a class of 100 (but I see no real upper limit on class size with the modified version of this activity).

“In Gallery Walk student teams rotate to provide bulleted answers to questions posted on charts arranged around the classroom. After three to five minutes at a chart or ‘station’ the team rotates to the next question. Gallery Walk works best with open ended questions, that is, when a problem, concept, issue, or debate can be analyzed from several different perspectives.” SERC Pedagogy in action


Teaching a large class. Photo by Maria Orjuela-Laverde, courtesy of Faculty of Engineering, McGill University

In most large classes in auditoriums, there is not the time or space for students to actually walk around the ‘gallery’. So instead I bring the ‘gallery’ of four provocative questions to groups of students on clipboards that are rotated around the classroom :

  • the class is split into four quadrants which are further divided into four groups (so ~5 people per group for a class of 100). Each group starts with a clipboard with one of the four questions and the four groups in the each quadrant should have the four different questions (good to check before starting).
  • Students are given 5-10 minutes to respond to the question on their clipboards and then clipboards are rotated until each group has answered each question. Students can constructively respond to previous groups answers to the same question.
  • After four rotations each group should have the question they started with and I ask a few groups to report out a summary to class which I synthesize on the board. In my case we end the activity with a vote of the ‘world’s biggest water problem’.

I find this an excellent way to start and/or end a term. In my case I teach a rather technical undergraduate engineering class about hydrology and water resources – this is an excellent tool to encourage students to think very broadly and creatively about the topic before and/or after we learn technical details.

This activity was inspired by conversations at the ‘Cutting Edge’ Early Career Geoscientist workshop in June 2012 College of William and Mary, Williamsburg, VA. The workshop is sponsored by the National Association of Geoscience Teachers (NAGT) with funding provided by the National Science Foundation Division of Undergraduate Education. I thank the workshop leaders, NAGT and NSF for this opportunity and encourage other early career geoscientists to check out future workshops.


Get every new post on this blog delivered to your Inbox.

Join other followers: