Here are the AGU presentation titles from the group this year:
Carrie Jensen and Kevin McGuire, Active Stream Length Dynamics in Headwater Catchments Spanning Physiographic Provinces in the Appalachian Highlands, H11E-1385, Monday Morning, Moscone South – Poster Hall
Scott Bailey, Kevin McGuire, Don Ross, Moving the Watershed Ecosystem Approach Beyond the Black Box with Sensor Technologies and New Conceptual Models, H42B-04, Thurs. 11:05 – 11:20, Moscone West – 3022
Kyle Corcoran, JP Gannon, Scott Bailey, Kevin McGuire, Mark Green, Biogeochemical Hotspots in Shallow to Bedrock Zones: Sources of Dissolved Organic Carbon (DOC) in the Appalachian Mountain Region of the Eastern USA, B51B-0424, Friday Morning, Moscone South – Poster Hall
Paolo Benettin, Pierre Queloz, Scott Bailey, Kevin McGuire, Andrea Rinaldo, Gianluca Botter, Modeling Hydrologic Transport through the Critical Zone: Lessons from Catchment-Scale and Lysimeter Studies, H51J-1522
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Tagged with: AGU
Paolo Benettin’s paper was just accepted, which was the result of his study abroad visit here in the lab during the fall 2013 and spring 2014. The manuscript explores water age-dependent transport in estimating weathering-derived solute export. The model predicts water travel time dynamics from water stable isotope data and represents geochemical dissolution at the catchment-scale as a simple first-order kinetic relationship based explicitly on the dynamic water travel time distributions. Paolo completed his dissertation last year at the University of Padova and is now a postdoc at EPFL (École polytechnique fédérale de Lausanne).
Abstract: We combine experimental and modeling results from a headwater catchment at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, to explore the link between stream solute dynamics and water age. A theoretical framework based on water age dynamics, which represents a general basis for characterizing solute transport at the catchment scale, is here applied to conservative and weathering-derived solutes. Based on the available information about the hydrology of the site, an integrated transport model was developed and used to compute hydrochemical fluxes. The model was designed to reproduce the deuterium content of streamflow and allowed for the estimate of catchment water storage and dynamic travel time distributions (TTDs). The innovative contribution of this paper is the simulation of dissolved silicon and sodium concentration in streamflow, achieved by implementing first-order chemical kinetics based explicitly on dynamic TTD, thus upscaling local geochemical processes to catchment scale. Our results highlight the key-role of water stored within the sub-soil glacial material in both the short- and long-term solute circulation. The travel time analysis provided an estimate of streamflow age distributions and their evolution in time related to catchment wetness conditions. The use of age information to reproduce a 14-year dataset of silicon and sodium stream concentration shows that, at catchment scales, the dynamics of such geogenic solutes are mostly controlled by hydrologic drivers, which determine the contact times between the water and mineral interfaces. Justifications and limitations toward a general theory of reactive solute circulation at catchment scales are discussed.
Benettin, P., Bailey, S.W., Campbell, J.L., Green, M.B., Rinaldo, A., Likens, G.E., McGuire, K.J., Botter, G., 2015. Linking water age and solute dynamics in streamflow at the Hubbard Brook Experimental Forest, NH, USA, Water Resources Research, doi: 10.1002/2015WR017552.
JP Gannon just had another paper accepted in Water Resources Research this week. The study suggests that dissolved organic carbon (DOC) in headwater streams may be generated from shallow to bedrock regions in the catchment, which mostly occur near the catchment divides and channel heads. The study also suggests that hydropedological patterns are critical to understanding DOC sources to streams.
Abstract: We investigated potential source areas of dissolved organic carbon (DOC) in headwater streams by examining DOC concentrations in lysimeter, shallow well, and streamwater samples from a reference catchment at the Hubbard Brook Experimental Forest. These observations were then compared to high frequency temporal variations in fluorescent dissolved organic matter (FDOM) at the catchment outlet and the predicted spatial extent of shallow groundwater in soils throughout the catchment. While near-stream soils are generally considered a DOC source in forested catchments, DOC concentrations in near-stream groundwater were low (mean = 2.4 mg/L, standard error = 0.6 mg/L), less than hillslope groundwater farther from the channel (mean = 5.7 mg/L, standard error = 0.4 mg/L). Furthermore, water tables in near-stream soils did not rise into the carbon rich upper B or O horizons even during events. In contrast, soils below bedrock outcrops near channel heads where lateral soil formation processes dominate had much higher DOC concentrations. Soils immediately downslope of bedrock areas had thick eluvial horizons indicative of leaching of organic materials, Fe, and Al and had similarly high DOC concentrations in groundwater (mean = 14.5 mg/L, standard error = 0.8 mg/L). Flow from bedrock outcrops partially covered by organic soil horizons produced the highest groundwater DOC concentrations (mean = 20.0 mg/L, standard error = 4.6 mg/L) measured in the catchment. Correspondingly, streamwater in channel heads sourced in part by shallow soils and bedrock outcrops had the highest stream DOC concentrations measured in the catchment. Variation in FDOM concentrations at the catchment outlet followed water table fluctuations in shallow to bedrock soils near channel heads. We show that shallow hillslope soils receiving runoff from organic matter-covered bedrock outcrops may be a major source of DOC in headwater catchments in forested mountainous regions where catchments have exposed or shallow bedrock near channel heads.
Gannon, J.P., Bailey, S.W., McGuire, K.J., Shanley, J.B., 2015. Flushing of distal hillslopes as an alternative source of stream dissolved organic carbon in a headwater catchment, Water Resources Research, doi: 10.1002/2015WR016927.
Published in the working life section of Science, Jeff provides some good advice for early career academics – it’s “critical to find one’s focus and voice and have it heard—quickly.” He discusses how early career scientists need to develop brand identity and reinforce this brand as much as possible. Defining the optimal degree of focus and brand width is key. Great advice!
Read more at http://www.sciencemag.org/content/349/6249/758.full?sid=1a3fc95e-5331-4930-b9b6-dd45ab2c9840.
A new textbook called Principles and Dynamics of the Critical Zone was just published. I co-authored a chapter of the book on Ecohydrology in the Critical Zone with Georgianne Moore, Peter Troch and Greg Barron-Gafford. Here is the publisher’s description of the book:
Principles and Dynamics of the Critical Zone is an invaluable resource for undergraduate and graduate courses and an essential tool for researchers developing cutting-edge proposals. It provides a process-based description of the Critical Zone, a place that The National Research Council (2001) defines as the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources.”
This text provides a summary of Critical Zone research and outcomes from the NSF funded Critical Zone Observatories, providing a process-based description of the Critical Zone in a wide range of environments with a specific focus on the important linkages that exist amongst the processes in each zone.
This book will be useful to all scientists and students conducting research on the Critical Zone within and outside the Critical Zone Observatory Network, as well as scientists and students in the geosciences – atmosphere, geomorphology, geology and pedology.
Moore, G.W., McGuire, K.J., Troch, P.A., Barron-Gafford, G. 2015. Chapter 8. Ecohydrology and the critical zone: processes and patterns across scales. In: Giardino, J. and Houser, C. (Eds.), Principles and Dynamics of the Critical Zone. Developments in Earth Surface Processes, Volume 19, pp. 239-266, Elsevier, Amsterdam, The Netherlands, doi: 10.1016/B978-0-444-63369-9.00008-2.
Kevin, Brian, and I went to Coweeta to improve the irrigation system. They installed a pressure pump to the water line, then we placed tipping bucket rain gauges at randomized locations, and then Brian turned on the water. Water pressure was high enough! We tuned each sprinkler head so that water reached just to the other side of the soil model. Data from the rain gauges showed how much water we sprinkled. Overall, the irrigation system looked very good. I will return to fine-tune the water pressure settings and irrigation timing, then wet up the soil model so that we can install more monitoring instruments. Before we left, I opened the met station data logger and found several wiggling wasp larvae inside their nest! I relocated them and, luckily, nobody was hurt.
Kevin, Jennifer, and I watch Brian turn on the sprinklers.
Closeup of sprinkler head.
Wasp nest inside met station data logger.
Tuned sprinkler heads spray water that was sampled by tipping bucket rain gauges in random locations.
Mt. Pleasant next to Mt. Washington. Left to right: Tyler Hampton (REU student), Kyle Corcoran (REU student), Carrie Jensen, Kevin McGuire, and Scott Bailey (USFS).
It’s that time of year again…the Hubbard Brook Cooperator’s Meeting! This year we celebrated the 60th anniversary of the Hubbard Brook Experimental Forest. We had a record attendance at the meeting, and as usual, it was full of great talks and good conversations with colleagues. Four REU students are working on hydropedology and stream network project this year. They are amazingly hard workers and full of great questions.
Posted in Lab news
Tagged with: Hubbard Brook
Two new papers are available in Water Resources Research on water travel time estimation in catchments. Both represent collaborations with colleagues to advance techniques in understanding the transient nature of travel time distributions. We’re getting closer and closer to answering the question: how old is that water in the stream?
Rinaldo, A., Benettin, P., Harman, C., Hrachowitz, M., McGuire, K., Van der Velde, Y., Bertuzzo, E., Botter, G., 2015. Storage selection functions: A coherent framework for quantifying how catchments store and release water and solutes, Water Resources Research, doi: 10.1002/2015WR017273.
Klaus, J., Chon, K.P., McGuire, K.J., McDonnell, J.J., 2015. Temporal dynamics of catchment transit times from stable isotope data, Water Resources Research, doi: 10.1002/2014WR016247.
Kevin, Brian, and I installed a reverse osmosis filtration system, an irrigation line, an electrical line, and several data instruments/loggers. This included pounding a 7-foot copper grounding rod into the ground. The filtration system is used to change the chemistry of local tap water to resemble that of rainfall for our experiment. Sunny weather, with only an occasional thundershower, helped the installation move on schedule.
There was quite a bit of vegetation growing in the soil model, to our surprise! It could have been due to warmth inside the hoop-house. I clipped the vegetation and Brian sprayed an herbicide to suppress future growth. Now that most of the infrastructure is built, I am thinking about the next trip to Coweeta, when I will install the rest of the instrumentation: (3) soil moisture and temperature probes, (3) tensiometers, (12) lysimeters, (5) rain gauge tipping buckets, and (1) piezometer; hundreds of meters of extension cables; and dozens of batteries!
Soil model when we first arrived. Note the growth of vegetation.
Raymond pounding a 7-foot copper grounding rod into the floor for the data logger, which will be connected to soil temperature and moisture probes and tensiometers.
Kevin and Brian installing sprinkler heads for the irrigation system.
Soil model with sprinkler heads, electrical line, meteorological station installed.