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Urban streams with green walls

ResearchBlogging.orgWill Dalen Rice and a friendNote: This post is a collaborative effort by Anne and guest blogger Will Dalen Rice, a graduate student in the Department of Geography and Earth Sciences at UNC Charlotte. He had the misfortune of taking a couple of courses from Anne this semester and has become a certified stream junkie, going out on rainy nights to see how high Charlotte’s urban streams are running.

Most cities were started around the idea of available surface water resources. Development and misuse of our streams (ex: “dilution is the solution to pollution”) has resulted in the modern urban stream. These streams are straight and good at carrying storm water, full of sediment and pollutants, and they lack good habitat for plants and animals. Now that we are beginning to notice how degraded and trashed these city waterways are though, scientists and engineers are beginning to attempt to address the form and function of these waterways to hopefully return them to a more “natural” (or at least aesthetically pleasing) state. While there are many stream restoration techniques, they often involve mechanical manipulation of the stream channel and banks and the planting of riparian plants along the stream corridor. As the streamside ecosystem redevelops, the idea is that health of the stream will also improve (leave it to nature to clean up our messes, given the chance).

For large urban streams, the standard practices in stream and habitat restoration are sometimes not possible, often because decades of infrastructure development have pinned the stream into a narrow corridor. So other approaches need to be considered, and Robert Francis and Simon Hoggart of King’s College London discuss ways that existing artificial structures can be put to work to mitigate some of the ecological impacts of urbanization. In the specific case of the River Thames in England, habitat development has been observed on man-made structures, and furthermore, certain types of man-made structures grow life better than others. Francis and Hoggart show that indeed plants (and therefore animals) can develop in a riparian zone better when brick and wood and rougher materials are used over concrete and steel. If concrete and steel already exist, adding brick and wood can further trap sediment for habitat growth (like gluing a cup of dirt to a steel wall). They suggest that this should become standard practice when thinking of restoration efforts in large, urban waterways.

The NOAA’s Northwest Fisheries Science Center says Thornton Creek in downtown Seattle exemplifies “the challenges facing rehabilitating urban streams.” But a look at the NOAA picture below shows that this stream is also emblematic of a riparian ecosystem that has developed within the constraints of the existing structures and maybe even a spontaneous model for the sort of restoration that Francis and Hoggart envision.

Seattle urban stream from NOAA website

Francis, R., & Hoggart, S. (2008). Waste Not, Want Not: The Need to Utilize Existing Artificial Structures for Habitat Improvement Along Urban Rivers Restoration Ecology, 16 (3), 373-381 DOI: 10.1111/j.1526-100X.2008.00434.x

When it rains a lot and the mountains fall down

Cross-posted at Highly Allochthonous

2006 debris flow deposit in the Eliot Glacier drainage, north flank of Mount Hood (Photo by Anne Jefferson)

The geo-image bonanza of this month’s Accretionary Wedge gives me a good reason to make good on a promise I made a few months ago. I promised to write about what can happen on the flanks of Pacific Northwest volcanoes when a warm, heavy rainfall hits glacial ice at the end of a long melt season. The image above shows the result…warm heavy rainfall + glaciers + steep mountain flanks + exposed unconsolidated sediments are a recipe for debris flows in the Cascades. Let me tell you the story of this one.

It was the first week of November 2006, and a “pineapple express” (warm, wet air from the tropic Pacific) had moved into the Pacific Northwest. This warm front increased temperatures and brought rain to the Cascades…a lot of rain. In the vicinity of Mt. Hood, there was more than 34 cm in 6 days, and that’s at elevations where we have rain gages. Higher on the mountain, there may even have been more rain…and because it was warm, it was *all* rain. Normally, at this time of year, the high mountain areas would only get snow.

While it was raining, my collaborators and I were sitting in our cozy, dry offices in Corvallis, planning a really cool project to look at the impact of climate change on glacial meltwater contributions to the agriculturally-important Hood River valley. Outside, nature was opting to make our on-next field season a bit more tricky. We planned to install stream gages at the toe of the Eliot and Coe glaciers on the north flank of Mt. Hood, as well as farther downstream where water is diverted for irrigation. But instead of nice, neat, stable stream channels, when we went out to scout field sites the following spring, we were greeted by scenes like the one above.

Because sometime on 6 or 7 November, the mountain flank below Eliot Glacier gave way…triggering a massive debris flow that roared down Eliot Creek, bulking up with sediment along the way and completely obliterating any signs of the pre-existing stream channel. By the time the flow reached the area where the irrigation diversion occur, it had traveled 7 km in length and 1000 m in elevation, and it had finally reached the point where the valley opens up and the slope decreases. So the sediment began to drop out. And debris flows can carry some big stuff (like the picture below) and like the bridge that was washed out, carried downstream 100 m and turned sideways.

2006 Eliot Glacier debris flow deposit (photo by Anne Jefferson)

2006 Eliot Glacier debris flow deposit (photo by Anne Jefferson)

In this area, the deposit is at least 300 m wide and at least a few meters deep.

Eliot Creek, April 2007 (photo by Anne Jefferson)

Eliot Creek, April 2007 (photo by Anne Jefferson)

With all the big debris settling out, farther downstream the river was content to just flood…

Youtube video from dankleinsmith of the Hood River flooding at the Farmers Irrigation Headgates

and flood…

West Fork Hood River flood, November 2006 from

West Fork Hood River flood, November 2006 from For the same view during normal flows, take a look at my picture from April 2007:

and create a new delta where Hood River enters the Columbia.

Hood River delta created in November 2006 (photo found at

Hood River delta created in November 2006 (photo found at

And it wasn’t just Mt. Hood’s Eliot Glacier drainage that took a beating in this event. Of the 11 drainages on Mt. Hood, seven experienced debris flows, including a rather spectacular one at White River that closed the main access to a popular ski resort. And every major volcano from Mt. Jefferson to Mt. Rainier experienced debris flows, with repercussions ranging from downstream turbidity affecting the water supply for the city of Salem to the destruction of popular trails, roads, and campgrounds in Mt. Rainier National Park (pdf, but very cool photos).

In the end, our project on climate change and glacial meltwater was funded, we managed to collect some neat data in the Eliot and Coe watersheds in the summer of 2007, and the resulting paper is wending its way through review. The November 2006 debris flows triggered at least two MS thesis projects and some serious public attention to debris flow hazards in the Pacific Northwest. They also gave me some really cool pictures.

FYI: NCED Summer Institute on Earth-surface Dynamics

I basically recommend anything this NCED group puts together. The short courses on Mountain Rivers and Sand-bed Rivers that I took as late-stage PhD student were absolutely fantastic.

In order to adequately describe the interactions among the physical, biological, geochemical, and anthropogenic processes that shape the Earth’s surface, we need to take a holistic, cross-disciplinary approach. Thus, the National Center for Earth-surface Dynamics (NCED) founded the Summer Institute on Earth-surface Dynamics (SIESD) as a forum to expose early-career scientists to laboratory experiments, fieldwork, and lectures on predictive Earth-surface science.

In 2010, the Summer Institute will focus on the science of rivers and vegetation. Participants will gain experience in: the basic physics of water-sediment-vegetation interaction; modeling the co-evolution of landscapes and their ecosystems; quantitative analysis of complex landscapes; LiDAR analysis of river topography and vegetation; and specifics of braided, meandering, and deltaic systems interacting with vegetation. In addition, students will gain hands-on experience with a suite of analytical tools including GeoNet (an automatic feature extraction tool for high resolution topography) and InVEST (a modeling environment to support environmental decision-making).The Institute will also expose students to broader-impacts research via the Science Museum of Minnesota and other NCED educational and diversity activities.

Eligibility: The Summer Institute is directed to graduate students in the final years of their PhD program, postdocs, or early-career scientists (three years from PhD). Applications from women, minorities, and individuals with disabilities are strongly encouraged.

Cost: NCED will make arrangements to cover local expenses related to participation in the Institute (enrollment, accommodations, breakfast, and lunch). However, students should remember they are responsible for the cost of transportation to/from Minnesota and all incidental expenses. Limited resources are available to cover travel expenses upon request.

Application Procedure: An online application is available at:

Lecturers (subject to change): Chris Paola, Gary Parker, Brad Murray, Gordon Grant, Steve Polasky, and Efi Foufoula-Georgiou. Additional lecturers will be announced on the course website.

Deadline: The application and all supporting materials must be received by June 25, 2010.

For more information, please visit

Delta upon Delta

For some reason the last few days have seen me browsing the semi-frozen areas of the Earth and in my search for the perfect thermokarst landscape, I’ve run across some really nice deltas. I don’t know anything about the one below other than its location in far northwestern Saskatchewan, but it looks to me like this river had built a beautiful fan delta only to see the lake shoreline dramatically change (perhaps as a result of isostatic rebound?) triggering the building of not one, but two, new fan deltas like Mickey Mouse ears on the margins of the old one.

The image below is from Google Earth. Here’s the Flash Earth permanent link:…

Posted via web from Pathological Geomorphology

More tributes to Reds Wolman from all those who miss him

About two months ago, I noted with great sadness the passing of a legendary figure in fluvial geomorphology, M. Gordon “Reds” Wolman, long-time professor at The Johns Hopkins University and inspiration to hundreds, if not thousands, of geomorphologists, hydrologists, and environmental scientists around the world.

In the past two months, Wolman’s students and colleagues have done an outstanding job of paying tribute to our hero. On April 11th, generations of Wolman’s students gathered on the Hopkins campus for a memorial service, which included a eulogy from a childhood friend and reflections from Hopkins geomorphology colleague Peter Wilcock. The day before the memorial, many of the attendees conducted their own Reds’ style field trip to some of his favorite locations in Baltimore County and waved their arms and debated some of the same questions Reds had spent decades pondering. (Sadly, I could not attend the celebration, because I was leading my hydrogeology class on a field trip to Congaree National Park, but somehow I feel like Reds would understand.)

Among the lasting tributes to Wolman are a couple of JHU web pages, two wonderful videos (below), and perhaps my favorite memorial ever:

A permanent memorial tribute will be installed outside the classrooms in Ames Hall where Reds Wolman taught for more than a half century. Stones provided by students, colleagues and friends from around the world will be constructed into a path in a shape that mirrors a meandering river.

For those of you still wondering what all the fuss was about (and still reading this post), please take a few more minutes and listen to the preface of one of Wolman’s seminal works and some reflections from Wolman’s colleagues and students (including, if you listen carefully, me) and from Wolman himself.



Reds is deeply missed by all who knew him, but these wonderful tributes give us a small way to hang on to the man who influenced, encouraged, and inspired us.

Deltas into Rivers: Chippewa River into the Mississippi River, Wisconsin

The Chippewa River drains the glaciated terrains of north-central Wisconsin including major outwash plains from the margins of the Laurentide Ice Sheet.  The sand carried by the Chippewa is a major sediment source for the Upper Mississippi River for tens of miles downstream.  The Chippewa forms a beautiful delta into the Mississppi River, as seen below, creating the only natural lake on the Mississippi, in the form of Lake Pepin (birthplace of water-skiing, by the way).  I like this delta because we don’t often think of riverine deltas forming in the rivers, and their propogating upstream and downstream effects. Plus, it makes a pretty contrast to the dissected blufflands of the Driftless area.

Flash earth link: If you zoom in on Flash Earth you can get some nice imagery of the sand bars and fluvial islands of the Chippewa as you move upstream, plus some nice long anastomosing reaches.

Posted via email from Pathological Geomorphology

The pathologically curvy Rio Grande Delta

I spent a summer in college staring at maps and aerial photographs of the Rio Grande delta in Texas and Mexico. Maybe now I can get some use out of it.  I was working with J.D.  Stanley at the Smithsonian’s NMNH and he pointed me to the apparently high sinuosity of deltaic channels on the Texas side of the Rio Grande delta.

According to my notes, the modern Rio Grande has a sinuosity of 2.075 in its delta, while Holocene channels have a sinuosity of 1.83, younger Pleistocene channels have a sinuosity of 1.81 and remnants of older Pleistocene channels have about 1.32. So our data suggests that the channels of the Rio Grande delta have gotten curvier over time. I also did a literature review of channel sinuosity in other deltas and found that the Rio Grande was indeed anomalously sinuous compared to many of the world’s major deltas.  In my review, only the Niger and Klangat Langat deltas were curvier. Unfortunately, we never came up with a good mechanism to explain why the Rio Grande was so curvaceous.

Indeed, if you look at the flash earth images (  below, you can see what caught our eye. One of the images is the majority of the delta (look for the anthropogenically straightened main outlet channel), one zooms in on the modern river mouth and area just to the north, one shows a portion of the southern, Mexico portion of the delta, and one shows the northern portion of the delta, which if I recall correctly has some of the oldest exposed deltaic deposits along with some eolian features (which can been seen in the image).

Posted via email from Pathological Geomorphology

Bombetoka Bay, Madagascar

Hunting for a Where on Google Earth location a while ago I ran across this wonderful tidally-influenced delta on the northwest coast of Madagascar. It is the mouth of the Betsiboka River and just north of the river mouth is the second largest port in Madagascar.

What struck me about the delta was not just the nice tug-of-war between riverine and tidal processes in shaping the islands, but the dramatic red color of the water in the Google Earth image (and others as well). This red color is symptomatic of the massive erosion resulting from rampant deforestation of the island.

The four photos are from Flash Earth, Google Earth, and the Gateway to Astronaut Photography, NASA Earth Observatory (ASTER satellite)

Flash earth permanent link:

Astronaut Photograph:

Earth Observatory ASTER image:

Posted via email from Pathological Geomorphology

Selected Resources for World Water Day

World Water Day 2010
More than one billion people (1 in 6) do not have access to adequate clean fresh water – which is defined as just 20 to 50 liters per day. (In contrast, the average American can use in excess of 400 liters per day indoors.) More than 2.5 billion people do not have access to basic sanitation facilities. Without sanitation, human and animal wastes reach drinking water supplies and illness proliferate. Diarrhea, caused by water-born pathogens, is the leading cause of illness and death in the world. And most of its victims are children under 5 years old.

Today is World Water Day, an annual recognition of the importance of freshwater and an opportunity for focusing attention on advocating for its sustainable management. World Water Day is organized by the UN Environmental Program. Each year has a particular theme, and in 2010 the theme is “Clean Water for a Healthy World.”


The all-around excellent Pulitzer Gateway “Downstream”is focused on water conflict and cooperation, water and economics, water and health, and water and climate. Of particular relevance for this World Water Day is the section on water and health, where I found the video and written account of women in Kakuma daily digging a dry riverbed for water because they couldn’t afford the 5 cents per jerry can fee for the clean, pumped water supplied by aid organizations and the local government.

(One thing you might notice if you watch some of these videos is that it is women and girls who are disproportionately affected by lack of access to clean water. Women are the ones who have to walk miles to fill jugs with water and girls drop out of school in order to do so. Improving access to water would give these women and girls additional opportunities to contribute to their own and their families’ economic well-being.)

In 2000, the UN set out its Millenium Development Goals, one of which is “By 2015, reduce by half the proportion of people without sustainable access to safe drinking water.” With five years to go, we haven’t gotten very far towards that goal. There are many organizations working to install wells and establish clean water supplies. There are also organizations working to develop and distribute affordable water purification technologies, some even using entrepreneurial solutions. Just as importantly, there are groups working to improve sanitation conditions. We need to break the taboo on sanitation and recognize it to be a necessary ingredient to preserving clean water resources. Unfortunately, all of these well-meaning organizations face significant limitations because of cost, political instability, hydrogeology, and climate.

No matter how much scientific geek-love I may have for streams and groundwater, mostly I take water for granted. Yet in other parts of the world, access to clean water is literally a matter of life or death. I’m glad for this year’s reminder of how fortunate I am, how far the world needs to go to meet basic human needs, and how many of the solutions are within our grasp, if concerted, adequately-funded efforts were made. Simply put, global health depends on access to adequate clean water and sanitation. It’s time to move water higher on our collective to-do list.

Conference presentation: Effects of river management & sediment supply on island evolution in Pool 6 of the Upper Mississippi River, southeast Minnesota

Watershed Hydrogeology Lab graduate student Brock Freyer has spent the last two years learning deeply about the hydrology, geomorphology, and sedimentology of the Upper Mississippi River System, as well as learning to use some sophisticated GIS techniques for 3-D analysis of topographic data. This week he is presenting the results of his work: “Effects of river management & sediment supply on island evolution in Pool 6 of the Upper Mississippi River, southeast Minnesota” at the Upper Midwest Stream Restoration Symposium. Brock is speaking in a session on Large River Restoration. Brock will be defending his M.S. thesis sometime in late spring.