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My picks of the November literature

It is not that there was no October literature to pick. My time to read articles simply disappeared in the lead-up to and excitement of the Geological Society of America meeting. This month, however, I am back on track and I will try to update this post as I move through the last few weeks of November.

Fussel, H-M. 2009. An updated assessment of the risks from climate change based on research published since the IPCC Fourth Assessment Report. Climatic Change (2009) 97:469–482. doi:10.1007/s10584-009-9648-5
The takeaway message is this: While some topics are still under debate (e.g., changes to tropical cyclones), most recent research indicates that things are looking even worse now than we thought a few years ago. Greenhouse gas emissions are rising faster than we anticipated, and we have already committed to substantial warming, which is currently somewhat masked by high aerosol concentrations. It is increasingly urgent to find mitigation and adaptation strategies. Not good.

Gardner, LR. 2009. Assessing the effect of climate change on mean annual runoff. Journal of Hydrology. 379 (3-4): 351-359. doi:10.1016/j.jhydrol.2009.10.021
This fascinating article starts by showing a strong correlation (r2 = 0.94) between mean annual runoff and a function of potential evapotranspiration and precipitation. The author then goes on to derive an equation that shows how temperature increases can be used to calculate the change in evapotranspiration, therefore solving the water budget and allowing the calculation of the change in mean annual runoff. Conversely, the same equation can be used to solve for the necessary increase in precipitation to sustain current runoff under different warming scenarios.

Schuler, T. V., and U. H. Fischer. 2009.Modeling the diurnal variation of tracer transit velocity through a subglacial channel, J. Geophys. Res., 114, F04017, doi:10.1029/2008JF001238.
The authors made multiple dye tracer injections into a glacial moulin and then measured discharge and tracer breakthrough at the proglacial channel. They found strong hysteresis in the relationship between tracer velocity and proglacial discharge and attributed this hysteresis to the adjustment of the size of a subglacial Röthlisberger channel to hydraulic conditions that change over the course of the day. Cool!

Bense, V. F., G. Ferguson, and H. Kooi (2009), Evolution of shallow groundwater flow systems in areas of degrading permafrost, Geophys. Res. Lett., 36, L22401, doi:10.1029/2009GL039225.
Warming temperatures in the Arctic and sub-arctic are lowering the permafrost table and activating shallow groundwater systems, causing increasing baseflow discharge of Arctic rivers. This paper shows how the groundwater flow conditions adjust to lowering permafrost over decades to centuries and suggests that even if air temperatures are stabilized, baseflow discharge will continue to increase for a long time.

Soulsby, Tetzlaff, and Hrachowitz. Tracers and transit times: Windows for viewing catchment scale storage. Hydrological Processes. 23(24): 3503 – 3507. doi: 10.1002/hyp.7501
In this installment of Hydrological Processes series of excellent invited commentaries, Soulsby and colleagues remind readers that although flux measurements have been the major focus of hydrologic science for decades, it is storage that is most relevant for applied water resources problems. They show that tracer-derived estimates of mean transit time combined with streamflow measurements can be used to calculate the amount of water stored in the watershed. They use their long-term study watersheds in the Scottish Highlands to illustrate how transit time and storage scale together and correlate with climate, physiography, and soils in the watersheds. Finally, they argue that while such tracer-derived storage estimates have uncertainties and are not a panacea, they do show promise across a range of scales and geographies.

Chatanantavet, P., and G. Parker (2009), Physically based modeling of bedrock incision by abrasion, plucking, and macroabrasion, J. Geophys. Res., 114, F04018, doi:10.1029/2008JF001044.
Over the past 2 decades, geomorphologists have developed much better insight into the landscape evolution of mountainous areas by developing computerized landscape evolution models. A key component of such models is the stream power rule for bedrock incision, but some have complained that is not physically based enough to describe. In this paper, the authors lay out a new model for bedrock incision based on the mechanisms of abrasion, plucking, and macroabrasion (fracturing and removal of rock by the impact of moving sediment) and incorporating the hydrology and hydraulics of mountain rivers. This could be an influential paper.

Payn, R. A., M. N. Gooseff, B. L. McGlynn, K. E. Bencala, and S. M. Wondzell (2009), Channel water balance and exchange with subsurface flow along a mountain headwater stream in Montana, United States, Water Resour. Res., 45, W11427, doi:10.1029/2008WR007644.

Tracer tests were conducted along 13 continuous reaches of a mountain stream to quantify gross change in discharge versus net loss and net gain. Interestingly, the change in discharge over some reaches did not correspond to calculations of net loss or net gain based on tracer recovery. These results suggests that commonly used methods for estimating exchange with subsurface flow may not be representing all fluxes. Bidirectional exchange with the subsurface, like that found in this paper, is likely to be very important for nutrient processing and benthic ecology.

Please note that I can’t read the full article of AGU publications (including WRR, JGR, and GRL) until July 2010 or the print issue arrives in my institution’s library. Summaries of those articles are based on the abstract only.

How to build a meandering river in your basement

This post is cross-posted at Highly Allochthonous. Please look over there for 15+ comments on the post.

Meandering rivers are characterized by regularly spaced bends that grow and cutoff and generally march downstream in a fairly orderly fashion. Click the image below to watch a movie of meander migration on the Allier River near Chateau de Lys, France


Movie 1. Meander bend migration and cut off using aerial photos and maps from: 1945,1960,1971,1980,1982, 1992, 1995, and 1997 on the Allier River, France. Created by A. Wilbers, originally found here.

Though meandering rivers are by far the most common river form on Earth, building a meandering river in a laboratory flume eluded scientists for decades. The conditions necessary to support self-maintaining meandering rivers were not known well enough to recreate in the laboratory. Flumes, or experimental channels, are a really important tool for understanding river processes, because sediment and water influxes can be tightly controlled and high precision measurements made.

Sand and gravel, the most common sediments in river banks, have low cohesion. In flumes, channels through sand and gravel, even if initially forced into a meander form, inevitably end up as wide channels with active braid bars. Solving the bank cohesion problem, by replacing sand and gravel with silt and clay, results in flume channels that have lots of curvature (sinuousity) but do not maintain their geometry through multiple meander cut-offs. Over the last 10 years, graduate students Karen Gran and Michal Tal working with Chris Paola at the University of Minnesota figured out how to make a self-sustaining single channel in coarse sediment. The key to creating a single channel was to plant alfalfa seedlings to give the banks some cohesion. You can see the results of alfalfa growth in a Quicktime video of Tal’s experiments. (Click the image below.)

capture1.pngMovie 2. Tal and Paola’s experiments with alfalfa seedlings and channel form. More movies of these experiments here.

If you watched the video, you’ll notice that while the channel is indeed single thread and it does move around, the meanders don’t move downstream in the relatively orderly fashion of a natural river. So the insight of alfalfa sprouts from Gran and Paola (2001) and Tal and Paola (2007) got geomorphologists a long way towards understanding the controls on meander self-maintenance in coarse-bedded rivers, but they didn’t quite reach the finish line.

Now, a paper in the Proceedings of the National Academy of Sciences by UC Berkeley graudate student Christian Braudrick, his advisor Bill Dietrich and collaborators Glen Leverich and Leonard Sklar from San Francisco State University reports that they have succeeded where so many others have failed. In a 17-m long, 6.7 m wide flume, Braudrick and colleagues created a self-sustaining meandering channel. Their work was featured on National Public Radio’s Science Friday show, which produced the following video giving the basics of Braudrick’s process.

Movie 3. Science Friday’s video about Braudrick et al’s experiments.

One of the key things mentioned in the video, but not explained is why the lightweight sediment was plastic. In slimming down a river to fit within a laboratory, researchers have to take into account all of the possible scaling effects. That’s why alfalfa seedlings are used to simulate the grasses and trees of a normal riparian zone, for instance. The power of the water, or its shear stress, is a function of depth, slope, fluid density, and gravity. Since the depth of flume channels is so much smaller than real rivers, it means that the shear stress available to move sediment is much lower. This means flumes can’t move fist sizes pieces of gravel and the size of the sediment in the study must be scaled down accordingly. Gravel scales down reasonably well to coarse sand, but sand scales down to silt, and silt has much different cohesive properties than sand. This is where the plastic came in, because the researchers wanted to create meanders using the alfalfa to create cohesive banks not by adding cohesive sediment. The plastic beads were the size of very fine sand and they lacked cohesion. Thus, the researchers created laboratory conditions of that mimicked natural rivers – channel banks where there was a mixture of sizes of non-cohesive sediment held together by roots.

When the flume was turned on, the little plastic beads moved both along the channel bed and suspended within the water column, much as sand would do in a natural channel. With a small initial curvature at the upstream end of the flume, meanders propogated downstream and began to grow and cut off. In previous alfalfa-only experiments ( Tal and Paola, 2007), each time meanders were cut off, a trough was left on the upstream side of the abandoned meander. In natural systems, these troughs get plugged with fine sediment and create oxbow lakes that eventually fill in. In the alfalfa-only, the troughs persisted, opening the possibility of islands developing in the channel. In Braudrick’s alfalfa+plastic experiments, the little plastic beads moving in suspension filled in the troughs at the upstream end of the abandoned meander, blocking future flow through that old pathway.

From Braudrick and colleagues’ results, it appears that sand and fine sediment have an important role to play in reinforcing and maintaining the meandering pattern of river channels. Out in the real world, such fine sediment is often regarded as an undesirable pollutant of coarse-bedded rivers, so these results have the potential to change the goals of river restoration and management. Plus, now that geomorphologists have a way to simulate realistic meandering rivers in the flume, new insights into the controls and behavior of meandering rivers are likely to start pouring in.

This post is cross-posted at Highly Allochthonous. Please look over there for 15+ comments on the post.

My picks of the September literature

Haggerty, Roy; Martí, Eugènia; Argerich, Alba; von Schiller, Daniel; Grimm, Nancy B. 2009. Resazurin as a “smart” tracer for quantifying metabolically active transient storage in stream ecosystems J. Geophys. Res., Vol. 114, No. G3, G03014
(Roy will be talking about this work in our session at the GSA Annual Meeting next month.)

Harman, C. J.; Sivapalan, M.; Kumar, P. 2009. Power law catchment-scale recessions arising from heterogeneous linear small-scale dynamics Water Resour. Res., Vol. 45, No. 9, W09404
(Ooh, this sounds really cool. I’ve been interested in heterogeneity in watersheds for a while, and this looks like an interesting take on the topic.)

Moussa, Roger 2009. Definition of new equivalent indices of Horton-Strahler ratios for the derivation of the Geomorphological Instantaneous Unit Hydrograph Water Resour. Res., Vol. 45, No. 9, W09406

Philip Brunner, Craig T. Simmons, Peter G. Cook
Spatial and temporal aspects of the transition from connection to disconnection between rivers, lakes and groundwater
Journal of Hydrology, 376: 159-169

Astrid Lambrecht, Christoph Mayer, 2009, Temporal variability of the non-steady contribution from glaciers to water discharge in western Austria, Journal of Hydrology, 376: 353-361.
(Relevant to my Mt. Hood work.)

I. P. Holman, M. Rivas-Casado, N. J. K. Howden, J. P. Bloomfield, A. T. Williams. 2009. Linking North Atlantic ocean-atmosphere teleconnection patterns and hydrogeological responses in temperate groundwater systems. Hydrologic Processes. 23(21): 3123-3126.
(The invited commentaries (like this one) in HydroPro are almost always worth a read to see what leading hydrologic thinkers are thinking about.)

Tiwari, V. M.; Wahr, J.; Swenson, S. 2009. Dwindling groundwater resources in northern India, from satellite gravity observations Geophys. Res. Lett., Vol. 36, No. 18, L18401
(This is at least the third paper I’ve seen on this topic in the past month. It is big big news.)

People just keep publishing interesting stuff.

Fiorillo, F. 2009. Spring hydrographs as indicators of droughts in a karst environment. Journal of Hydrology 373: 290-301.

Rosenberry, D.O. and J. Pitlick. 2009. Effects of sediment transport and seepage direction on hydraulic properties at the sediment–water interface of hyporheic settings. Journal of Hydrology 373: 377-391.

Gresswell, R. et al. 2009. The design and application of an inexpensive pressure monitoring system for shallow water level measurement, tensiometry and piezometry. Journal of Hydrology 373: 416-425.

Fryar, A.E. 2009. Springs and the Origin of Bourbon [Historical Note], Ground Water, 47(4): 605-610.

Cardenas, M. Bayani. 2009. Stream-aquifer interactions and hyporheic exchange in gaining and losing sinuous streams Water Resour. Res., Vol. 45, No. 6, W06429

Selker, John; Ferre, Ty P. A. 2009. The ah ha moment of measurement: Introduction to the special section on Hydrologic Measurement Methods Water Resour. Res., Vol. 45, No. null, W00D00

Hodgkins, Glenn A. 2009. Streamflow changes in Alaska between the cool phase (1947-1976) and the warm phase (1977-2006) of the Pacific Decadal Oscillation: The influence of glaciers Water Resour. Res., Vol. 45, No. 6, W06502

Matott, L. Shawn; Babendreier, Justin E.; Purucker, S. Thomas Evaluating uncertainty in integrated environmental models: A review of concepts and tools Water Resour. Res., Vol. 45, No. 6, W06421

Orr, Cailin H.; Clark, Jeffery J.; Wilcock, Peter R.; Finlay, Jacques C.; Doyle, Martin W. Comparison of morphological and biological control of exchange with transient storage zones in a field-scale flume J. Geophys. Res., Vol. 114, No. G2, G02019

Katsuyama, Masanori; Kabeya, Naoki; Ohte, Nobuhito Elucidation of the relationship between geographic and time sources of stream water using a tracer approach in a headwater catchment Water Resour. Res., Vol. 45, No. 6, W06414

Phillips, J.D. 2009. Landscape evolution space and the relative importance of geomorphic processes and controls. Geomorphology, 109:79-85.

And last but not least:

Pretty much all of: Hydrological Processes, Special Issue: Hyporheic Hydrology: Interactions at the Groundwater-Surface Water Interface. Issue Edited by Stefan Krause, David M. Hannah, Jan H. Fleckenstein. Volume 23, Issue 15, 2009.

Most especially this article:
Boano, F., Revelli, R., and Ridolfi, L. 2009. Quantifying the impact of groundwater discharge on the surface-subsurface exchange, Hydrological Processes, 23(15): 2108-2116.

More new papers I'm itching to read

Godsey, S.E., J.W. Kirchner, and D.W. Clow, 2009. Concentration-discharge relationships reflect chemostatic characteristics of US catchments, Hydrological Processes 23 (13): 1844-1864.

Tetzlaff, D., J. Seibert, and C. Soulsby. 2009. Inter-catchment comparison to assess the influence of topography and soils on catchment transit times in a geomorphic province; the Cairngorm mountains, Scotland. Hydrological Processes 23 (13): 1874-1886.

Lyon, S.W., S.L.E. Desilets, and P.A. Troch. 2009. A tale of two isotopes: differences in hydrograph separation for a runoff event when using delta-D versus delta-18O. Hydrological Processes 23 (14): 2095-2101.

Bloomfield, J.P., D.J. Allen, and K.J. Griffiths. 2009. Examining geological controls on baseflow index (BFI) using regression analysis: An illustration from the Thames Basin, UK, Journal of Hydrology, 373: 164-176.

Pascal Goderniaux, Serge Brouyère, Hayley J. Fowler, Stephen Blenkinsop, René Therrien, Philippe Orban, Alain Dassargues. 2009. Large scale surface–subsurface hydrological model to assess climate change impacts on groundwater reserves, Journal of Hydrology, 373: 122-138

On the top of my "to read" list

Every week there’s a virtual flood of enticing looking papers from the tables of contents that arrive in my in-box. Here are the ones that look most enticing to me this week:

Jencso, K. G., B. L. McGlynn, M. N. Gooseff, S. M. Wondzell, K. E. Bencala, and L. A. Marshall (2009), Hydrologic connectivity between landscapes and streams: Transferring reach? and plot?scale understanding to the catchment scale, Water Resour. Res., 45, W04428, doi:10.1029/2008WR007225.

Hrachowitz, M., C. Soulsby, D. Tetzlaff, J. J. C. Dawson, and I. A. Malcolm (2009), Regionalization of transit time estimates in montane catchments by integrating landscape controls, Water Resour. Res., 45, W05421, doi:10.1029/2008WR007496.

Navarre-Sitchler, A., C. I. Steefel, L. Yang, L. Tomutsa, and S. L. Brantley (2009), Evolution of porosity and diffusivity associated with chemical weathering of a basalt clast, J. Geophys. Res., 114, F02016, doi:10.1029/2008JF001060.

Foulquier, A., F. Malard, S. Barraud, and J. Gibert. 2009. Thermal influence of urban groundwater recharge from stormwater infiltration basins. Hydrological Processes. 23(12): 1701-1713. doi: 10.1002/hyp.7305

Tague, C.L. 2009. Assessing climate change impacts on alpine stream-flow and vegetation water use: mining the linkages with subsurface hydrologic processes. Hydrological Processes. 23(12): 1815-1819. doi:10.1002/hyp.7288

Schenk, E.R. and C.R. Hupp. 2009 Legacy Effects of Colonial Millponds on Floodplain Sedimentation, Bank Erosion, and Channel Morphology, Mid-Atlantic, USA. Journal of the American Water Resources Association. 45(3):597-606. doi:10.1111/j.1752-1688.2009.00308.x

Jacob, J.S. and R. Lopez. 2009 Is Denser Greener? An Evaluation of Higher Density Development as an Urban Stormwater-Quality Best Management Practice. Journal of the American Water Resources Association. 45(3):687-701. doi:10.1111/j.1752-1688.2009.00316.x

Fraley, L.M., A.J. Miller, and C. Welty. 2009. Contribution of In-Channel Processes to Sediment Yield of an Urbanizing Watershed. Journal of the American Water Resources Association. 45(3):748-766. doi:10.1111/j.1752-1688.2009.00320.x

Some of these papers will be useful for my teaching (Fraley et al. and Schenk and Hupp), one will be useful in revising a paper from my Ph.D. research (Navarre-Sitchler et al.), and the rest are of general research for on-going projects or projects in the design stage. I hope they give you a flavor of the sort of things that set spinning the research gears in my mind.