This Youtube video was recently posted from a field tour several of us gave during the 50th anniversary of the Hubbard Brook Ecosystem Study. There is good background on forested watershed studies, gaging streams, hydropedology, and local historical ecology at Hubbard Brook. Mark Green (USFS & Plymouth State), JP Gannon (Western Carolina University), Nick Grant (USFS), and Charlie Cogbill all make appearances.
A new student, David Lee, joined our lab this week. David completed his B.S. at the University of Florida in environmental engineering in 2015.
David was most recently working for the US Forest Service as a forestry technician/wilderness ranger and was stationed on the Eldorado National Forest in Pollock Pines, CA.
David will be working on a project based at the Hubbard Brook Experimental Forest in New Hampshire. Welcome to Blacksburg David!
Carrie Jensen was awarded a student seed grant through the Virginia Water Resources Research Center for her dissertation work on storm dynamics of expansion and contraction of temporary headwater streams. Andy Dolloff, with the US Forest Service Southern Research Station and the Department of Fish and Wildlife Conservation at Virginia Tech, is her Co-PI on the grant.
Carrie also contributed to a manuscript that was published online last week in Geophysical Research Letters. The study expanded on a geostatistical method described in McGuire et al. (2014), by developing a spatial stream network model of strontium isotopic composition of stream water in a large Alaska river basin. The model provided a means to quantify the influence of landscape versus in-stream processes on strontium isotopic composition of rivers.
2016), Dendritic network models: Improving isoscapes and quantifying influence of landscape and in-stream processes on strontium isotopes in rivers, Geophys. Res. Lett., 43, doi:10.1002/2016GL068904.
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Dr. Charley Kelly, a former lab member and now with the Division of Forestry and Natural Resources, West Virginia University, had a paper accepted in Geophysical Research Letters this week. The study re-examines several paired watershed studies from the Coweeta Hydrologic Lab, but focuses on high flows, low flows, and interactions with precipitation patterns.
Abstract: Increases in extreme precipitation events of floods and droughts are expected to occur worldwide. The increase in extreme events will result in changes in streamflow that are expected to affect water availability for human consumption and aquatic ecosystem function. We present an analysis that may greatly improve current streamflow models by quantifying the impact of the interaction between forest management and precipitation. We use daily long-term data from paired watersheds that have undergone forest harvest or species conversion. We find that interactive effects of climate change, represented by changes in observed precipitation trends, and forest management regime, significantly alters expected streamflow most often during extreme events, ranging from a decrease of 59% to an increase of 40% in streamflow, depending upon management. Our results suggest vegetation might be managed to compensate for hydrologic responses due to climate change to help mitigate effects of extreme changes in precipitation.
Kelly, C. N., K. J. McGuire, C. F. Miniat, and J. M. Vose (2016), Forest management changes streamflow response to increasing precipitation extremes, Geophysical Research Letters, 43, doi:10.1002/2016GL068058.
Congratulations to Carrie on being selected for a CUAHSI 2015 Pathfinder Fellowship. Carrie’s proposal titled, “Stream network expansion and contraction dynamics in headwater catchments throughout the Appalachian Highlands,” will be supported by CUAHSI (Consortium of Universities for the Advancement of Hydrologic Science, Inc.), which will provide her with an opportunity to enhance her dissertation project to include the Fernow Experimental Forest as field site. This summer she will spend several weeks at Fernow mapping stream channels allowing her to add the Allegheny Mountain section of the Appalachian Plateau physiographic province to field sites throughout the Appalachian Highlands. Carrie recently presented preliminary data from this project at the American Geophysical Union fall meeting in December.
Special Issue Tracer Advances Reviews
Tracer advances in catchment hydrology (pages 5135–5138) Kevin J. McGuire and Jeffrey J. McDonnell
Ecohydrological separation in wet, low energy northern environments? A preliminary assessment using different soil water extraction techniques (pages 5139–5152) Josie Geris, Doerthe Tetzlaff, Jeffrey McDonnell, James Anderson, Graeme Paton and Chris Soulsby
A preliminary assessment of water partitioning and ecohydrological coupling in northern headwaters using stable isotopes and conceptual runoff models (pages 5153–5173) Doerthe Tetzlaff, James Buttle, Sean K. Carey, Marjolein H. J. van Huijgevoort, Hjalmar Laudon, James P. McNamara, Carl P. J. Mitchell, Chris Spence, Rachel S. Gabor and Chris Soulsby
Established methods and new opportunities for pore water stable isotope analysis (pages 5174–5192) Matthias Sprenger, Barbara Herbstritt and Markus Weiler
Stable water isotopes suggest sub-canopy water recycling in a northern forested catchment (pages 5193–5202) Mark B. Green, Bethany K. Laursen, John L. Campbell, Kevin J. McGuire and Eric P. Kelsey
Tracking residence times in hydrological systems: forward and backward formulations (pages 5203–5213) Paolo Benettin, Andrea Rinaldo and Gianluca Botter
Velocities, celerities and the basin of attraction in catchment response (pages 5214–5226) Keith Beven and Jess Davies
Advancing tracer-aided rainfall–runoff modelling: a review of progress, problems and unrealised potential (pages 5227–5240) Christian Birkel and Chris Soulsby
Transit time distributions, legacy contamination and variability in biogeochemical 1/fα scaling: how are hydrological response dynamics linked to water quality at the catchment scale? (pages 5241–5256) Markus Hrachowitz, Ophelie Fovet, Laurent Ruiz and Hubert H. G. Savenije
Using concurrent DNA tracer injections to infer glacial flow pathways (pages 5257–5274) Helen E. Dahlke, Andrew G. Williamson, Christine Georgakakos, Selene Leung, Asha N. Sharma, Steve W. Lyon and M. Todd Walter
A tracer to bridge the scales: on the value of diatoms for tracing fast flow path connectivity from headwaters to meso-scale catchments (pages 5275–5289) Julian Klaus, Carlos E. Wetzel, Núria Martínez-Carreras, Luc Ector and Laurent Pfister
Application of isotope hydrograph separation to understand contributions of stormwater control measures to urban headwater streams (pages 5290–5306) Anne J. Jefferson, Colin D. Bell, Sandra M. Clinton and Sara K. McMillan
I have been going to Coweeta every one or two weeks for the past two months to monitor sprinkling events on the soil model. Although I am measuring only one thing, water, being precise is actually very difficult. There are 5 high-resolution tipping buckets on the hillslope to measure samples of input and one large tipping bucket at the bottom of the model to measure outflow.
I experimented with placement of PVC collectors that are designed to capture spatial variability of the input by expanding the collection areas and positions of each input tipping bucket. Then I experimented with acrylic collectors, which are longer and smoother. Finally, I put specimen cups out along a grid on the model to measure input by hand. It is a dependable low-tech, high-resolution solution.
On the last trip of this year I shut down and winterized the model. That means disconnecting the water supply to the irrigation system, shutting off the reverse osmosis pump, and draining the water from the lines and water tank, all in case of a hard freeze, which is uncommon but possible. My instruments, e.g., soil probes and tensiometers, are sitting in the shed, ready for installation in an upcoming trip.
The hillslope model with tipping buckets and data logger installed.
Calibrating the outflow tipping bucket (500 mL per tip).
Closeup of the outflow tipping bucket.
PVC collectors expand the area of water sampled, helping to capture spatial variability.
A grid of cups set out on the model give an accurate, high-resolution estimate of water input to the soil model.
Wiring soil moisture/temperature probes, tensiometers, and tipping bucket to the data logger in the dorm room.
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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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.