The Secret Life of Rivers from S Solomon Leaping Frog Films on Vimeo.
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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.
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.
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.
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.
Here’s the grainy video I’ve been showing for years, but it’s still a great way to picture bedload transport: http://geofaculty.uwyo.edu/heller/SedMovs/Dietrich.htm. Kind of sorry about the grainy pun.
Here’s a nice close up video of some large bed sediments, from John Gaffney:
And some much smaller sediments moving across a coarse bed:
There are more videos by John Gaffney where those came from: http://www.youtube.com/user/flyer0lines/videos?view=pl
You can also enjoy this nice top down and cool sidelit view of sand and fine gravel: http://serc.carleton.edu/details/files/31376.html
Curious about how it all happens? Watch a quick primer from Dawn Summer at UC Davis:
Dawn has also got a great set of lecture notes available too. Or, consider taking my Fluvial Processes class at some point down the road.
Cross-posted at Highly Allochthonous
This summer we were treated to not one but two dam removals on the Cuyahoga River, ~10 miles downstream from Kent. Those following me on twitter know that I obsessed about these removals all summer long, first as they were delayed by weeks of high water, then as they got started and I got to watch first on the live “dam cam” and then in person. But the video compresses a whole summer of waiting, watching, and obsessing into two and a half glorious minutes, complete with music. This is, without a doubt, what youtube was invented for.*
If that dam removal video merely served to whet your appetite for dam busting, I have a few other videos you might enjoy. First, there’s there’s an excellent 8 minute documentary on Marmot Dam on the Sandy River, Oregon, which explains the science that led up to this removal, features the excitable Gordon Grant, and shows the action unfolding. If you just want to cut to the action, you can’t beat the “blow and go” (that would be the technical term) of the Condit Dam removal in Washington. Finally, a feature length movie called DamNation is coming our way in 2014. I’m so excited, I can hardly stand it. I’m going to go watch the videos a few more times.
Cross-posted at Highly Allochthonous
We’ve been having one of those perfect spring weeks, where the weather is warm and sunny, the flowers are blooming, and there is nothing more enticing at the end of a workday than to take a nice long wander down by the local river. Fortunately, I can do that right from my front door – exploring the Cuyahoga River, as it flows through Kent. I’ve blogged a couple of times already about the Cuyahoga, but today I want to share some views that I couldn’t have shared 10 years ago, because they would have been underwater.
For 168 years, a dam stood across the Cuyahoga River, under the main street bridge, and impounded water for a couple of miles upstream. In 2004, the dam was modified to let the river be free-flowing through town. The arched stone dam face was preserved but the remnants of a Pennsylvania and Ohio Canal lock structure were removed, creating a narrow chute in the river where once there was a full blockage. After the reservoir drained, some of the sediments were regraded to form a well-signed little heritage park behind the dam.
Above the dam site, the river is confined to a fairly narrow bedrock gorge with class 2 rapids. In a few places you can easily get down to it and see some nicely potholed rock in the riverbed. Kayakers call this a pin spot.
While we were wandering down there a few evenings ago, we met an angler who caught and released two small trout from the river in the space of about five minutes. There was no fish passage around the Kent Dam before it was removed, so I’m taking the trout as a good sign of some ecological recovery in this section of the river. Another good ecological sign has been spotted a few miles downstream. Rebuilding of another bridge over the river in Kent has been delayed so that endangered native mussel beds can be relocated.
I know that the dam removal decision in 2004 was controversial in the community – generations had grown up with the dam as a local landmark and it was on the National Register of Historic Places – but when I walk along this section of the river, I am impressed not only by the wonderful ecology and geomorphology of this little river that runs through our downtown, but I’m also impressed by the community’s embrace of the free-flowing Cuyahoga. On this day, so important to Kent’s history, it gives me hope that we can overcome the wrongs and divisions of the past and work together to make a better future for both our communities and the world around us.
Today, Brock Freyer will be defending the results of his M.S. research. The title of his research project is: Fluvial Response to River Management and Sediment Supply: Pool 6 of the Upper Mississippi River System, Southeastern Minnesota.
Brock’s committee is composed of Anne Jefferson (advisor), John Diemer and Ross Meentemeyer.
The defense is on Tuesday April 23, 2013, at 1:30 pm in McEniry 307 of UNC Charlotte. As Brock is currently located in Alaska, this will be a Skype defense. All are welcome to attend.
In this age of environmental restorations and rehabilitations, the scale and extent of projects have been getting larger and more expensive. In the Upper Mississippi River System (UMRS) the U.S. Army Corp of Engineers (USACE) has begun the task of restoring the negative effects that over a century of river management has incurred. Due to the scale and cost of such projects, it is essential to understand the natural and human processes that have affected the river system. In the UMRS, erosion and land loss are considered the dominant geomorphological trend, but Pool 6 of the UMRS is an exception to this norm. In Pool 6, deposition and land growth in recent decades have allowed the river morphology to begin reverting to its condition prior to intense river management. Through the application of varied chronological data sets within ArcGIS, spatial variations were measured to better understand where and why changes have occurred. A nested study area approach was applied to Pool 6 by dividing it into three scales: a general Pool wide observation; a smaller more in-depth observation on an area of island emergence and growth in the lower pool; and a subset of that section describing subaqueous conditions utilizing bathymetric data. The results from this study have indicated that site-specific geographic and hydrologic conditions have contributed to island emergence and growth in Pool 6. In Pool 6 land has been emerging at an average rate of 0.08km2/year since 1975. Within lower Pool 6, land has been emerging on an average rate of 18m2/year since 1940. The bathymetric subset has shown that sediments on average have gained 2.41m in vertical elevation, which translates into just under 828,000 m3 of sediments being deposited in 113 years. By identifying and describing these conditions river managers will be able to apply such knowledge to locate or reproduce similar characteristics within degraded sections of the UMRS. If the observations hold true in other locations, restoration efforts will be cheaper, more self-sustaining, promote natural fluvial dynamics, and ultimately be much more successful.
We are currently preparing a manuscript for publication.
No excited Gordon like at Marmot Dam, but this is one exciting “blow and go” dam removal video. This was Condit Dam on the White Salmon River in Washington in October 2011. Spectacular to watch, and even neater knowing that there was important (and hair-raising) science being done both upstream and downstream of the dam throughout the dam removal process.
A student and I are working on finishing a project that has lingered for too many years: a careful analysis of the cumulative effects of river management on islands in the lower part of Pool 6 of the Mississippi River, near my hometown of Winona, Minnesota. There will be a MS thesis soon and hopefully a journal manuscript shortly to follow that, but for now, I’m enjoying discovering new and old research and resources on “the father of waters.”
First, check out this 17-minute silent film on the 1927 Mississippi River flood:
For more information on the film made by the Signal Corps in the 1930s, head here: http://archive.org/details/mississippi_flood_1927
Then, check out this 2012 publication from the USGS on “A Brief History and Summary of the Effects of River Engineering and Dams on the Mississippi River System and Delta.”
Finally, there’s a paper just out in Geophysical Research Letters by Frans et al. titled “Are climatic or land cover changes the dominant cause of runoff trends in the Upper Mississippi River Basin?.”
And that’s my afternoon reading sorted.
There’s nothing particularly deterministic about starting a new year on January 1st. Our wall calendars happen to do so because of the circumstances of history. For hydrologists in the northern hemisphere, January 1st is not a great time to declare one year dead and a new one born. So instead, we transition between years on the 1st day of October. October 1st, 2012 marks day 1 of the 2013 water year. But, why?
Many hydrologic analyses involve calculating statistics on an annual basis. We might want to calculate annual streamflow to determine how much drier 2012 was than 2011. Or we might want to look for trends in the size of floods. For the example of flood statistics, the most common way to get a time series of floods is to identify the largest flood occurring in each year. This “annual peak flow” record is then used within the framework of a probability distribution function to assign a probability of given size flood occurring in any one year. (Problematically, this has been called a “flood frequency distribution”, leading to unnecessary confusion on the part of the public, but I digress…)
We use only the largest flow each year to calculate statistics because it avoids statistical complication. Principally, we want to ensure all of our events are independent of each other. Let’s say there are two days with really high flows in a year. The highest flow is 27.8 m3/s and the second flow is 24.1 m3/s. If the first measurement was made on January 29th and the second one was from March 18th, then these two data are independent (i.e., not the same flood). But if one is from January 29th and the other is January 30th, they are clearly not independent and should not both be used to calculate statistics as if they were. So, we try to avoid this dependence issue by using only the largest flow each year.
Here’s where we come back to the idea of the water year. Let’s use an example from my local stream gage – the Cuyahoga River at Hiram Rapids. There was a big flood on December 31st, 1990 – the biggest flood of the whole year – reaching a peak flow of 71.4 m3/s. On January 1st, 1991 the water was still high – 66.8 m3/s. After that excitement, the rest of 1991 was pretty dry and flow never again gets anywhere near as high, peaking at 25.0 m3/s in early March. How do we calculate the statistics? If we used the calendar year as our basis, we’d end up double counting that late December flood and we’d throw our flood statistics off.
Instead, hydrologists use October 1st as our cut-off date. In many parts of the Northern Hemisphere, summer is a period of low streamflow, driven by strong evapotranspiration and atmospheric circulation patterns. (A prominent exception to the lack of summer flooding is when tropical cyclones make landfall.) In winter, rain-on-snow can produce large floods in some regions, while decreased evapotranspiration and more frontal storms increase the chances of flooding in some southern regions. In the spring, seasonal snowmelt produces flooding in northern and alpine regions. That leaves the autumn as the period least likely to have frequent flooding. Also, because evapotranspiration is subsiding with cooler temperatures, soil moisture and stream flow don’t tend to be recovering from their low points in the summer. So autumn is a time of transition and a time when extremes are unlikely. The graphs below illustrate this for my local stream gage, but similarly shaped distributions would likely exist for many other gages in the US and beyond.
Thus, it’s a perfect time of year to the clear the books and declare a new year for hydrologic statistics. And it’s got as much or more physical rationale than when we change the calendar on the wall. Happy New Water Year Everyone!