This semester I’m teaching Environmental Earth Science to a fantastic group of students at Kent State. In tomorrow’s class about fossil fuels, we’ll be talking about coal formation, use, and environmental consequences. A big one I think they should be aware of is the practice of mountaintop removal mining in West Virginia. We’ve already talked about it a bit, but I think this video gives some nice visuals, even if the narration veers a bit from overly dramatic to “boys with toys”.
From the Smithsonian:
Several well-respected scientists are working to figure out the impact of mountaintop removal mining on stream ecosystems. The coal companies haven’t exactly lined up to fund their work and provide access to the sites. So what *do* we know about the impacts of mountaintop mining on Appalachian streams and rivers? Here’s just one example, from the abstract of Bernhardt and Palmer (2011):
Southern Appalachian forests are recognized as a biodiversity hot spot of global significance, particularly for endemic aquatic salamanders and mussels. The dominant driver of land-cover and land-use change in this region is surface mining, with an ever-increasing proportion occurring as mountaintop mining with valley fill operations (MTVF). In MTVF, seams of coal are exposed using explosives, and the resulting noncoal overburden is pushed into adjacent valleys to facilitate coal extraction. To date, MTVF throughout the Appalachians have converted 1.1 million hectares of forest to surfacemines and buried more than 2,000 km of stream channel beneath mining overburden. The impacts of these lost forests and buried streams are propagated throughout the river networks of the region as the resulting sediment and chemical pollutants are transmitted downstream. There is, to date, no evidence to suggest that the extensive chemical and hydrologic alterations of streams by MTVF can be offset or reversed by currently required reclamation and mitigation practices.
What’s the connection between Kent, Ohio and mountaintop mining? Our energy company buys coal from West Virginia mountaintops. See what this looks like on Google Earth. You can use the site to find the connection for your area.
ilovemountains.org is full of information and pleas for action from those opposed to mountaintop mining.
Kent State University Department of Geology’s Watershed Hydrology class visited the Susquehanna Shale Hills Critical Zone Observatory on April 5-6, 2014. Penn State post-doc Pamela Sullivan gave them a tour of the watershed and its instrumentation, with a focus on how the measurements could contribute to understanding how hydrology drives landscape evolution on shales. The students were introduced to the challenges of hydrologic field work as they attempted to produce a continuous flow of water from a 75′ foot deep well on the watershed’s ridgeline. On Sunday, the students learned and practice water quality sampling protocols and collected water samples from streams and shallow wells in the CZO watershed and in watersheds with differing geology.Temperature, pH, specific conductance, and DO were measured in the field, and ions, cations, and stable isotopes will be measured in laboratories at Penn State and Kent State. The students will discuss these data in class over the next several weeks as they integrate their understanding of how geology and topography control hydrologic flowpaths, streamflow generation mechanisms, and water quality.
Kent State watershed hydrologists in front of the CZO sign. Photo by Pam Sullivan, April 2014.
Pam Sullivan explains how an ISCO water sampler works.
Collecting a water sample from a well at the SSH CZO.
Kimm Jarden and Sebastian Dirringer are put to work cleaning a water retrieval system for one of the deeper wells in the CZO.
Recording data on the YSI from one of the shallow wells at the CZO.
The class stayed on the shores of Lake Perez, which has been drained for the last few years to enable repairs on the dam. The lake has just begun refilling, but while empty it has created some interesting research opportunities.
Kent State students enjoyed seeing a mostly empty reservoir. It’s neat to be able to see a dam, spillway, and what the reservoir bottom looks like without any water.
Pam Sullivan describes the well field at Katie Creek. This area will soon be inundated by the refilling of Lake Perez. Some wells are being raised up, so that Penn State scientists can assess the effects of the reservoir refilling on local groundwater dynamics.
Kent State students at work collecting water samples at the Katie Creek well field.
Krista Booth collects a water sample from Lake Perez, which integrates all of the other watersheds we sampled.
I’ll try to add some more beauty shots of the CZO watershed at some point, but I wanted to be able to show our class in action in the field.
Yesterday, I had the pleasure of being interviewed by the lovely Bethany Brookshire for her Eureka!Lab blog at Student Science, part of Society for Science and the Public. You can check out the interview on Eureka!Lab or scroll down to watch the video.
I loved doing the interview, for three reasons. First, I like talking about my science (what scientist doesn’t?). Second, Bethany is a friend and a blossoming science writer. But most importantly, Society for Science and the Public (SSP) is a great organization working to foster “understanding and appreciation of science and the vital role it plays in human advancement: to inform, educate, and inspire.” They are the publishers of Science News and Science News for Students, and they organize the premiere scientific competitions for middle school and high schools. These competitions are what got me engaged with science and encouraged to pursue a scientific career. So I’m always happy to help SSP in any way I can.
The video interview below is aimed at communicating to middle school students about what I do as a professor and hydrologic scientist. After a somewhat awkward start, I hope I did a good job of sharing the excitement and challenges of what I do in a fairly non technical way.
Today in Fluvial Processes, I’ll be talking about sediment transport. It’s one of those subjects that can easily get bogged down in lots and lots of math, but I prefer to start out with getting students to watch and describe the processes that occur as grains move along the bed before we start in on the physics and math.
I was hired as part of a cluster hire focused on urban ecosystems at Kent State University, and while my research has a significant urban component to it, I had not taught an urban-focused class… until this past semester, when I created a new class in Urban Hydrology. Urban hydrology is a fascinating and relevant topic, but its not part of the standard curriculum for geology students in the US. Where urban hydrology is typically taught is at the graduate level to civil engineering students, and follows on courses on hydraulics, fluid mechanics, etc. Thus, the content and approach taken in civil engineering Urban Hydro classes was not quite what I wanted for the senior geology majors and graduate students in my class, most of whom had no experience with hydrology before arriving in my classroom. This class was my first full course taught at Kent State, so it was a big semester of learning about the students here and how to effectively teach to them. While I think my students learned a lot in my class, I can say with some confidence that I learned just as much from the experience of teaching a new topic to a new audience.
At the beginning of my course planning, I set four learning objectives for the students:
Understand the natural and human factors that regulate hydrologic processes in urban areas
Evaluate watershed land use changes and associated hydrologic impacts
Describe methods to mitigate the effects of urbanization on aquatic systems
Analyze the scientific literature on urban aquatic systems and discuss the approaches and main conclusions with fellow scientists and the public
Upon reflection, the first two objectives have some significant overlap, though “evaluation” requires a different set of skills than “understanding.” These two objectives were the primary focus of the first half of the semester, in which I introduced students to the concepts of watersheds, water budgets, and hydrographs, and had them work through the USDA NRCS handbook TR-55 “Urban Hydrology for Small Watersheds” (pdf link) with a real example from the Cleveland metropolitan area. Overall I’m very happy with how this part of the course went, because I took students from not knowing how to define a watershed given a topographic map to being able to solve an applied hydrologic problem in an urban setting.
The first half of the course could also be summed up as “how we got to where we are today in urban watersheds,” and my goal for the second half was to help students understand “where do we go from here.” This is where objectives 3 and 4 came into greater play. We talked about principles and practices of stormwater control and low impact development, stream restoration, solving the legacy problem of combined sewer overflows, and attempts at watershed-scale approaches to reducing stormwater inputs to streams. I organized two optional field trips – one to look at stream restoration and dam removal sites in Kent (with help from the Ohio EPA) and surrounding towns and one lead by Cleveland Metroparks to look at stormwater BMPs and stream restoration in the West Creek watershed in Parma. The culminating project for this half of the class was the design of rain garden. While I’m reasonably happy with how this half of the class went, there are some tweaks I’d like to make for the future. I need to tie the topics covered in the second half of the semester into a more cohesive unit, and I need to rethink my fourth learning objective (re: scientific literature), because I didn’t do as a good of a job as I would like with implementing it. We certainly read quite a number of papers, and they wrote reflective essays about them, but the discussion with the public part didn’t happen.
I’m quite pleased with the final project though. In many neighborhoods, this rainfall that lands on a rooftop is delivered to driveways, streets, or pipes that lead to the storm sewer network and straight to streams. The goal of rain gardens is to “disconnect” the rooftop and treat the water on-site, returning the hydrology to a more natural state. The class worked in teams of three as competing consulting firms angling for a design-build contract on the rain garden. They had to survey the site to quantify impervious surface, soil characteristics, and lot and topographic limitations. Then using a variety of resources that they’d identified for rain garden design and construction, the teams developed plans that detailed size, position, soil characteristics, and planting for the rain garden. On the last day of class they presented their designs to each other. I didn’t actually ask the students to construct the rain garden (that’s something Chris and I have taken on over the summer, since it is in our front yard), but several have asked how the process is going. (I may post some pre-, syn- and post-project pictures later.)
I also had students participate in water quality data collection and analysis for the Cuyahoga River in Kent. I think this was a very valuable way for the students to gain a small amount of experience with hydrologic data from hypothesis generation and testing, to quality control of field measurements, to putting their results in the context of the literature. I’d like to keep a version of this project in future iterations of the course, but I want to tie it more explicitly into the course objectives.
I’m not likely to teach the course again for at least two years, but I’m hopeful that I can build off of what I did last spring to create an even better Urban Hydrology class at Kent State. In the meantime, almost all course materials can be found on my website, which I hope will be a resource for other people interesting in learning more about this fascinating and important field of hydrology.
Combined sewers are pipes that catch both sewage and stormwater and route it to a waste water treatment plant. In dry weather, it’s all sewage in the pipes. In small rain storms, the pipes carry sewage mixed with stormwater and it all goes to the wastewater treatment plant to get cleaned up and returned to a stream or lake. The origins of combined sewers predate waste water treatment, when there was little distinction between stormwater and sewage and stream and city dwellers just wanted the foul-smelling, disease-festering stuff out of their way as soon as possible. Later, engineers and public health folks added the crucial waste water treatment plant step to the system but the sewers remained combined. Combined sewers were common until the early 20th century, so over 772 communities in the US, mostly in the Northeast and Great Lakes regions have combined sewers, as shown on this map from the US EPA:
US EPA map of Combined Sewers. Click for source.
Most of the time, combined sewers route all of the water to the waste water treatment plant, and all is relatively well. But in large storms, the volume of stormwater and sewage can overwhelm the waste water treatment capacity. If the volume of water was too much to treat, you can imagine the pipes starting to fill up with sewage. If there were no “pressure release valve” on the system, urban dwellers in combined sewer cities would see the sewage/stormwater cocktail start to back up into their basements, sinks, … and, you get the picture. Fortunately for those city residents, there is a “pressure release valve in the system,” but it’s a solution that creates more problems downstream, literally. When flows in the combined sewers are too great to be treated, the sewage/stormwater cocktail overflows out of the pipe network and into local streams. Then you’ve got raw sewage in your stream and that’s not pretty, or healthy, or environmentally friendly. This is the infamous combined sewer overflow or “CSO.”
US EPA diagram of a combined sewer in dry and wet weather. From U.S. Environmental Protection Agency, Washington, D.C. “Report to Congress: Impacts and Control of CSOs and SSOs.” Document No. EPA 833-R-04-001 found on Wikimedia commons. Click for source.
Here’s a Northeast Ohio Regional Sewer District video explaining combined sewers and touting their treatment system:
Under the Clean Water Act, cities and sewer districts can be required to bring their raw sewage discharges down to acceptable levels by reducing the frequency and magnitude of combined sewer overflows (CSOs). Right now, Cleveland, the District of Columbia, Philadelphia, and other cities are under mandate to reduce their CSO discharges. This is a big, expensive undertaking because we’re talking about billions of gallons of overflows each year and thousands of miles of combined pipe network underneath the city. Big problems require big solutions, so how are the cities dealing with their CSO problem? It turns out that they are taking a range of different approaches.
In Cleveland, waste water treatment and stormwater are managed by the Northeast Ohio Regional Sewer District (NEORSD). Their “consent decree” with the EPA was filed in July 2011, and according to that decree, they have 25 years to reduce CSO volumes by 90%. That’s taking the CSOs from 4.5 billion gallons per year to the still non-trivial 494 million gallons per year. If they meet that goal, 98% of all wet weather flows will be treated before being released to a stream. The price tag for this ambitious project is $3 billion, and it has been termed “Project Clean Lake” in homage to Cleveland’s Lake Erie shoreline. a source of regional pride.
How is NEORSD planning to reduce CSOs? With a lot of digging. Most of the money and effort is being spent on “gray infrastructure” – big engineering projects. BIG engineering projects. NEORSD is boring 7 tunnels, each 2-5 miles long, up to 24 feet in diameter, and up to 300 feet below the ground or lake bottom. These tunnels will intercept the combine sewers before they overflow and store the water until the treatment plants have capacity to treat it.
The 7 future storage tunnels of Cleveland’s combined sewers. Image courtesy NEORSD. Click for larger.
This is a massive undertaking, and it’s just getting started. The videos below show the first tunnel boring machine arriving in Cleveland and a tour of the tunnel first tunnel to begin construction. You can follow the progress of the tunnel boring on the NEORSD blog.
But it’s not just tunnels, NEORSD is also enhancing their wastewater treatment capacity and spending $42 million on green infrastructure. Green infrastructure is defined as “a range of stormwater control measures that use plant/soil systems, permeable pavement, or stormwater harvest and reuse, to store, infiltrate, or evapotranspirate stormwater.” These can include things like green roofs, green streets, bioretention swales, and other projects. The goal is control 44 million gallons of would-be stormwater using green infrastructure, with projects completed in the next 8 years. Those numbers are nothing to sneer at it, but it’s 1% of the current combined sewer overflow volume and 1.5% of the budget. The fact that the budget % is bigger than the volume percent may hint at why green infrastructure isn’t being used more broadly in Cleveland.
Washington DC is taking a somewhat different approach than Cleveland. One-third of DC is served by combined sewers, and they are spending $2.6 billion over 25 years to reduce their overflow problem, which is currently about 2.5 billion gallons per year. DC Water has nicknamed their CSO program the “Clean Rivers Project.” Like Cleveland, they are also building large storage tunnels, improving their waste water treatment plants, and rehabilitating pumping stations. Unlike Cleveland, DC will actually be separating the sewers in some areas, sending sewage and stormwater down different pipes from each other. In DC, green infrastructure seems to get only a rhetorical nod, rather than a significant component of the budget. Their plan says they will “advocate implementation of Low Impact Development,” but they’ve only budgeted $3 million for it, a mere 0.1% of their overall project cost. However, they do have the world’s best explainer video.
Philadelphia is taking a radically different approach. Like Cleveland and DC, their price tag comes out to about $3 billion over 25 years. However, in Philadelphia it’s a “Green City, Clean Waters” program and green infrastructure steals the show. Philadelphia’s goal is to “reduce reliance on construction of additional underground infrastructure” by pushing extensive green infrastructure throughout the city. In other words, they don’t want to dig tunnels. Instead, they want to green acres:
Each Greened Acre represents an acre of impervious cover within the combined sewer service area that has at least the first inch of runoff managed by stormwater infrastructure. This includes the area of the stormwater management feature itself and the area that drains to it. One acre receives one million gallons of rainfall each year. Today, if the land is impervious, it all runs off into the sewer and becomes polluted. A Greened Acre will stop 80–90% of this pollution from occurring.
Philadelphia’s rationale for making green infrastructure their big push centers around social and economic benefits to come and their historic heritage as a park city. Their video is all about people, not all about pipes:
Philadelphia’s vision is the most radical departure from a traditional “grey infrastructure” approach like that pursued in Cleveland, DC and other cities. There’s certainly an aesthetic and emotional appeal behind greening a city and its stormwater. This is the way many people want to move urban hydrology in the 21st century, integrating the built and natural environment more closely than we’ve done in the past. But it will be interesting to watch where Philadelphia succeeds and if and where it fails, as the fully green infrastructure approach could be seen as much riskier than a traditional engineering-driven approach. Fortunately, EPA is devoting some funding to research on the effectiveness of Philadelphia’s project. I won’t be doing that work directly, but I will be following it closely and think it would be fascinating to put together a more rigorous multi-city analysis of approaches and outcomes.
More broadly, the combined sewer overflow problem is a fantastic example of how our environmental and societal choices are constrained by decisions made in the past. No one today would build a combined sewer, but yet millions of people live in cities served by them, thousands of engineers, scientists, and sewer district workers work with them, and billions of dollars are being spent trying to mitigate the problems they cause. We can’t just rebuild cities from the underground up, so we have to work with what we’ve inherited and try to make decisions that won’t cause consternation for future generations.
Note: This blog post is adapted from the lecture I gave today in Urban Hydrology. If I’ve gotten anything wrong or missed an important point, please let me know and I’ll try to make it better for current and future students.
Next week my Urban Hydrology class embarks on their first project: exploring the potential water quality changes in the Cuyahoga River as it flows through the City of Kent, which is really the first good-sized town on its path to Lake Erie.
Beginning February 5th, we’ll be collecting near-daily water quality measurements of Cuyahoga River water as it flows through Kent. Using the data we collect, we’ll attempt to answer the following questions:
• How does water quality change as the river flows through an urban area?
• How does water quality vary with respect to discharge in the Cuyahoga River?
Each student will sign up for one weekday on the class calendar. On the assigned day, that student will be responsible for taking a suite of measurements at 2-4 locations. The measurements we will take are (1) turbidity, (2) specific conductance, and (3) temperature and we will also collect water samples for later analysis on the Picarro water isotope analyzer. Each student will be required to take one set of measurements at the base of the steps just upstream of Main Street and one set of measurements at the beach just downstream of Summit Street. Students with access to cars are also encouraged to take measurements at the River Bend Road boat launch (at Kent’s upstream end) and at the Middlebury Road boat launch (at Kent’s downstream end). Details of each measurement technique and each site are [in the linked document].
River access just upstream of the Main Street bridge in Kent. This is one of the spots we’ll be using to sample the river.
This week’s mini-assignment for my urban hydrology class reads thus: “In 1-2 paragraphs, describe your hometown (or some other city you know well) in terms of its location, size, and form and why it is that way (i.e., historical context). Then write a paragraph describing your city’s relation to water. For example, what is the water supply and where is wastewater disposed? Are there local water bodies or water issues important to the community? You don’t need to include references with your assignment, but you should check your facts if you are unsure about anything.”
Because I’m a water geek, and I wanted to model a good response to these questions, I present not one, but two, reflections on cities I’ve known well and how those cities relate to water.
I grew up in Winona, Minnesota, a town of about 28,000 people in the southeastern corner of Minnesota. The main part of the city is situated in the middle of the Mississippi River floodplain, with the main channel on one side and a former channel (now lake) on the other. The Winona area was inhabited by Native Americans for millennia, prior to its establishment by white settlers in 1851. Winona’s location along the river made it an important link for railway and steamboat transportation, and Winona was the second place on the Mississippi to be crossed by a railroad bridge (opened in 1891). Winona grew rapidly, and by 1900 had almost 20,000 residents. Winona was a major sawmilling center (with logs floated down the river to the mills), and Winona is still a major port on the river for loading agricultural products onto barges. In southeastern Minnesota, the Mississippi River sits in a ~500 foot deep valley, so as the city has grown larger, it has spread outwards into tributary valleys and up onto the plateau. However, most of the population still lives on the floodplain, and most of the developed area (including pretty much all of the industrial and commercial areas) is in the valley bottom.
As is apparent by the paragraph above, Winona as a city is intricately tied to the Missisisippi River, physiographically and economically. River recreation (boating, fishing, duck hunting) is also a major past-time (and economic contributor) for Winonans. The river holds pride of place in town, but it was also a source of major and frequent flooding until 1985 when an 11-mile levee was built surrounding the town. Other than the occasional flood (now more a curiosity than a catastrophe), periodic public engagement with dredging of sand from the river bottom, and the enjoyment of boat trips on the river, I would say that Winonans’ aren’t particularly attentive to water issues, because it is abundant and out of their way. The city gets its water supply from a Cambrian sandstone aquifer several hundred feet below town, where water is abundant and good quality. It disposes its treated wastewater into the river at the downstream end of town. The big water issue I remember growing up, was about water quality in the Lake, which was quite degraded by the invasive exotic, Eurasian water milfoil. There is actually a water issue that has cropped up over the last several years in the region, which is getting local attention, and that is the mining of “frack sand” from the local sandstone formations. This is getting attention because of problems with heavy truck traffic in town, blowing sand from exposed storage piles, and from destruction of rural areas where the sandstone is being mined. However, to me, it is ultimately a water issue, because those sandstone formations are the regional aquifers. It’s not clear to me yet what effect the mining will have on local or regional water quality, but it seems like an issue to watch.
I spent five years living in Charlotte, which is the largest city in North Carolina, with a metropolitan population of 1.8 million people. Charlotte is a major financial center, and also the home of NASCAR. The city was founded around 1755 at the intersection of two Native American trading paths, and it was a “hornet’s nest of rebellion” during the American Revolution, being the first place that city leaders signed a declaration of independence from Great Britain. Charlotte’s history includes being close to the site of the first gold boom in the US, and becoming a major cotton processing center and railroad hub. Banking and NASCAR rose to prominence since the 1970’s, and the region has experienced explosive population growth (and urban sprawl) since then. The population of the city itself has gone from 241,000 in 1970 to over 730,000 in the 2010 census. There is a relatively small, high density city center surrounded by miles of low density residential, commercial, and industrial development. The gentle rolling topography of the Piedmont forms no barriers to the geographic expansion of the urban area. Several small towns have been agglomerated by the urban area, and many people commute from these communities into the city center or across the city.
The Catawba River, which has a watershed area of 3343 miles upstream of the South Carolina border (Charlotte’s southern boundary), flows through the urban area a few miles west of downtown Charlotte. The River is impounded in a series of reservoirs used for hydroelectric generation by Duke Energy, and was one of the first rivers in the country used for that purpose. Most of the land along the river is privately owned by relatively affluent people, and there are only a few public parks on the reservoirs. Power-boating recreation is popular with those along the river, but swimming is banned in the county in which Charlotte sits, because of concerns about liability. The river forms the water supply for the city, because the fractured crystalline rocks in the area don’t support pumping of large groundwater volumes. Wastewater is treated and disposed of back into the river (farther downstream) or into local streams. There are a number of small urban streams that flow through the city, and these streams are quite prone to flooding during heavy rainstorms. The city and county have undertaken a major stream restoration and stormwater management program to try to reduce flooding hazards, and a series of greenways have been established along the some of the streams. When I moved to Charlotte in 2007, we were in the middle of an intense drought, and subject to limitations on outdoor water use. However, as soon as the drought lifted, local water conservation mindfulness seemed to disappear too. There is an illusion of abundance of water in the southeastern US, even though as population grows water supplies are becoming stressed (Atlanta is a stark example of this). In a recent book, author Cynthia Barnett highlighted Charlotte as a prime example of a city that was “disconnected” from its water supply, meaning that the people of the area lacked a water culture or ethic that would encourage conservation and sustainable use.
I probably spent about 20 minutes writing each piece, but I’m fairly familiar with the water issues and setting in each area (see above: I’m a water geek). So it might take you a bit longer to do a similar amount of writing. One essay is 499 words, and the other is 528 words, but you could write less and still cover the relevant information. I haven’t included hyperlinks to lots of sources here, because I didn’t require that of my students, but I might go back later and add them, because it just seems like wasting the capabilities of the web to not do so.
Lake Malawi, from an astronaut photograph, accessed on Wikipedia
In Urban Hydrology this semester, I’m asking my students to complete mini-assignments related to each week’s reading. I’ve been doing a lot of reading lately about East African Rift Lakes, particularly Lake Malawi. I wanted to give my students an example of a excellent and not so great responses to the sorts of prompts they might see on their mini-assignment reading responses, so I gave myself the same assignment. I’m not looking for length in these answers, I’m looking for thoughtfulness.
Here are the questions I’ve posed to my students this week.
Based on what you have read and your pre-existing hydrologic knowledge, answer the following questions.
What is one thing you learned that you thought was particularly interesting or important, and why?
What is one thing that you would like more help understanding?
And here are a range of responses I could have written about my own reading on Lake Malawi.
For the first question: Excellent Answer (fulll credit): “I learned that Lake Malawi is the fourth largest lake in the world by volume, and that it was formed by the East African Rift. Lake Malawi is more than 560 km long, but only 75 km wide. It averages almost 300 m deep, and its deepest point is 706 m. This sort of shape and bathymetry are direct results of the rifting process. This got me interested in what the other really big lakes are and whether they are rift lakes too, so I went to Wikipedia and found a list of the largest lakes in the world by volume. The biggest five (Baikal, Tanganyika, Superior, Malawi and Vostok) are all a result of active or failed rifting. Other large lakes on the list seem to be related to glacial erosion (e.g., Michigan (#6) and Huron (#7)). I think this is particularly interesting because it suggests that parts of the world without a history of rifting or glaciation don’t have access to the large volume of freshwater stored in very big lakes. This probably makes a difference in the hydrology and regional climate and may affect the way societies have developed in different areas.”
Very Good Answer (full credit): “I learned that Lake Malawi is the fourth largest lake in the world by volume, and that it was formed by the East African Rift. Lake Malawi is more than 560 km long, but only 75 km wide. It averages almost 300 m deep, and its deepest point is 706 m. On the map, it didn’t seem to cover as big an area as some other African lakes. I thought that was really interesting because I had no idea it was such a big lake. I realize now that lakes that have large surface areas might not have large volumes, if they are shallow and lakes that have smaller surface areas might be really big, if they are deep.”
OK Answer (some credit): “I learned that Lake Malawi is the fourth largest lake in the world by volume, and that it was formed by the East African Rift. I thought that was really interesting because I had no idea it was such a big lake.”
Not So Good Answer (little credit): “I learned that Lake Malawi is the fourth largest lake in the world by volume, and that it was formed by the East African Rift.”
For the second question: Good Answer (full credit): “I read that Lake Malawi is formed from three half grabens. I understand that when you have extensional forces and down drop a block, you get a graben. But I need help understanding how you can get half grabens and how that might affect the history of the lake.”
(I like this sort of answer because it tells me where the question has come from, what part of the difficult material is already understood, where the difficulty lies, and why the student thinks the understanding is important.)
OK answer (some credit): “Half grabens.”
(Sure, they’re a bit confusing. But why do you want help understanding them?)
Unacceptable answer (little credit): “I understood everything in the reading.”
(This is unacceptable because there is always more to learn and it exhibits lack of intellectual curiosity about the material.)
Urban Hydrology will be offered in the Department of Geology at Kent State University. With the course number 40095/50095/60095, it is designed to appeal to both undergraduate and graduate students looking for an interdisciplinary exposure to water science in cities and built environments. The course will meet on Tuesdays and Thursdays from 12:30 to 1:45. If you are a Kent State student, please join us.
Image credits: SOPAC, where the image is attributed to SEQ Healthy Waterways Partnership (http://www.healthywaterways.org) and US Green Building Council, where it is attributed to NC DENR.