New paper on lidar DEM evaluation by Cody Gillin

2015_MayGillin, C.P., Bailey, S.W., McGuire, K.J., Prisley, S.P., 2015. Evaluation of lidar-derived DEMs through terrain analysis and field comparison, Photogrammetric Engineering & Remote Sensing, 81(5): 387-396, doi: 10.14358/PERS.81.5.387.


Topographic analysis of watershed-scale soil and hydrological processes using digital elevation models (DEMs) is commonplace, but most studies have used DEMs of 10 m resolution or coarser. Availability of higher-resolution DEMs created from light detec- tion and ranging (lidar) data is increasing but their suitability for such applications has received little critical evaluation. Two different 1 m DEMs were re-sampled to 3, 5, and 10 m resolu- tions and used with and without a low-pass smoothing filter to delineate catchment boundaries and calculate topographic metrics. Accuracy was assessed through comparison with field slope measurements and total station surveys. DEMs provided a good estimate of slope values when grid resolution reflected the field measurement scale. Intermediate scale DEMs were most consistent with land survey techniques in delineating catchment boundaries. Upslope accumulated area was most sensitive to grid resolution, with intermediate resolutions producing a range of UAA values useful in soil and groundwater analysis.

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New paper published on erosion modeling on forest roads

jofKris Brown had another paper published.  The study evaluated the model Water Erosion Prediction Project (WEPP) in predicting event-based sediment yield and runoff for a series of rainfall experiments on six stream-crossing sections of forest roads with different intensities of best management practices.  For more information, please check out the paper.

Brown, K.R., McGuire, K.J., Hession, W.C., and Aust, W.M., 2015. Can the Water Erosion Prediction Project (WEPP) model be used to evaluate BMP effectiveness from forest roads? Journal of Forestry, doi: 10.5849/jof.14-101.

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Brian McGlynn visited us last week



Brian McGlynn from Duke University visited the lab last week.  Brian gave a great seminar that was co-hosted by ICTAS and the Water Center.  It was well attended and generated great discussion.  We all thank Brian for coming to visit us at Tech.

Posted in Lab news, Seminars, Visitors

Looking for undergraduate student researchers: 2015 Hubbard Brook REU program

REU students (Tyler and Patricia) receiving some soils training from the State Soil Scientist.

Water quality, soils and fluvial geomorphology of a headwater stream network

Seeking 4 undergraduate student researchers for National Science Foundation funded REU program at the Hubbard Brook LTER site in New Hampshire.

Project description: Where do forests end and streams begin? This seemingly simple question turns out to defy an easy answer. Headwater streams, such as those at Hubbard Brook, comprise the vast majority of riverine miles, set regional water quality, and represent the interface between terrestrial and aquatic systems. As a team, we will explore the vast network of headwater streams across the Hubbard Brook Valley and their relationships to their tributary watersheds. Students will participate in both group and individual research. For the group project we will come together as a team several times during the program to sample portions of the Hubbard Brook tributary stream network at a fine spatial scale over a short time period. These “snap shots” will be used to decipher potential mechanisms that regulate spatial water quality patterns. Each student will also develop an individual project based on the student’s interests and background. Individual projects could include (1) mapping stream channel geomorphology and exploring relationships to topography and streamflow quantity, (2) measuring hydrologic exchange between streams and groundwater, and (3) characterizing variation in soil morphology and chemistry in streamside environments. Skills in GIS, field survey and mapping, soil description and sampling, and water sampling and analysis will be practiced and developed.

Project mentors include: Drs. Kevin McGuireScott Bailey, Mark Green, Denise Burchsted.  REU students will also work closely with Ph.D student Carrie Jensen.

Applications are due February 6, 2015.

For application information go to and for project inquiries, contact Kevin McGuire.

Posted in Jobs, Undergraduate research

AGU 2014…check out this session on tracers!

McGuire is co-convening a session with Josie Geris, Daniele Penna, and Julian Klaus called “New Developments in Tracer Applications in Catchment Hydrology.”  If you are attending the meeting next week, please come to our session.  The program is available below:

Papers – Tuesday, Moscone West


Read more ›

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New review paper on tracers in northern catchments

HPcoverAbstract: We examine how tracer studies have enhanced our understanding of flow paths, residence times and sources of stream flow in northern catchments. We define northern catchments as non-glacial sites in the temperate conifer/boreal/permafrost zone, focussing our review mainly on sites in North America and Europe. Improved empirical and theoretical understanding of hydrological functioning has advanced the analytical tools available for tracer-based hydrograph separations, derivation of transit time distributions and tracer-aided rainfall-runoff models that are better able to link hydrological response to storage changes. However, the lack of comprehensive tracer data sets still hinders development of a generalized understanding of how northern catchments will respond to change. This paucity of empirical data leads to many outstanding research needs, particularly in rapidly changing areas that are already responding to climatic warming and economic development. To continually improve our understanding of hydrological processes in these regions our knowledge needs to be advanced using a range of techniques and approaches. Recent technological developments for improved monitoring, distributed hydrological sensor systems, more economic analysis of large sample numbers in conjunction with novel, tracer-aided modelling approaches and the use of remote sensing have the potential to help understanding of northern hydrological systems as well as inform policy at a time of rapid environmental change.

Tetzlaff, D, Buttle, J., Carey, S.K., McGuire, K., Laudon, H., Soulsby, C. 2014. Tracer-based assessment of flow paths, storage and runoff generation in northern catchments: a review, Hydrological Processes, doi: 10.1002/hyp.10412.


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Paper published on mapping of hydropedologic spatial patterns

sssa-logoA paper from Cody Gillin’s master’s thesis was accepted last week.  The manuscript titled “Mapping of hydropedologic spatial patterns in a steep headwater catchment” will be published in a special issue on hydropedology in the Soil Science Society of America Journal.  This paper appears in the special issue with another paper on the same project, which was led by Rebecca Bourgault from the University of Vermont.

Gillin, C.P., Bailey, S.W., McGuire, K.J., Gannon, J.P. 2015. Mapping of hydropedologic spatial patterns in a steep headwater catchment, Soil Science Society of America Journal, doi: 10.2136/sssaj2014.05.0189.

Abstract: A hydropedologic approach can be used to describe soil units affected by distinct hydrologic regimes. We used field observations of soil morphology and geospatial information technology to map distribution of five hydropedologic soil units across a 42 ha forested headwater catchment. Soils were described and characterized at 172 locations within watershed 3, the hydrologic reference catchment for the Hubbard Brook Experimental Forest, NH. Soil profiles were grouped by presence and thickness of genetic horizons. Topographic and bedrock metrics were used in a logistic regression model to estimate the probability of soil group occurrence. Each soil group occurred under specific settings that influence subsurface hydrologic conditions. The most important metrics for predicting soil groups were Euclidean distance from bedrock outcrop, topographic wetness index, bedrock-weighted upslope accumulated area, and topographic position index. Catchment scale maps of hydropedologic units highlight regions dominated by lateral eluviation or lateral illuviation, and show that only about half the catchment is dominated by podzolization processes occurring under vertical percolation at the pedon scale. A water table map shows the importance of near-stream zones, typically viewed as variable source areas, as well as more distal bedrock-controlled zones to runoff generation. Although the catchment is steep and underlain by soils developed in coarse-textured parent material, patterns of groundwater incursion into the solum indicate that well drained soils are restricted to deeper soils away from shallow bedrock and the intermittent stream network. Hydropedologic units can be a valuable tool for informing watershed management, soil carbon accounting, and understanding biogeochemical processes and runoff generation.

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2014 AGU presentations

AGU_logoHere are the AGU presentation titles from the group this year:

Benettin, P., Kirchner, J., McGuire, K., Rinaldo, A., Botter, G., 2014. Linking tracers and travel time distributions: the emergence of age mixing patterns, Abstract H21L-01, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA (Invited)

Gannon, J., McGuire, K., Bailey, S., Shanley, J., 2014. Simply active, or contributing too? Investigating the hydrologic connectivity of shallow water tables in a headwater catchment, Abstract H31I-0756, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA (Invited)

Klaus, J., Chun, K., McGuire, K., McDonnell, J., 2014. A new non-parametric framework to determine time-variant catchment transit times and their distributions, Abstract H23L-1041, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA

McGuire, K., Bailey, S., Gannon, J., Likens, G., Buso, D., Torgersen, C., Lowe, W., 2014. Multi-Scale Variations in Streamwater Chemistry and Hydropedological Implications for Hotspot Development, Abstract H14E-03, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA (Invited)

Morse, J., Duran, J., Morillas, L., Roales, J., Bailey. S., McGuire, K., Groffman, P., 2014. Searching for hot spots and hot moments of soil denitrification in northern hardwood forests, Abstract H14E-04, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA

Weiler, M., McGuire, K., Stahl, K., 2014. A Reanalysis of Forest Disturbance Impacts on Streamflow, Abstract H12D-02, Fall Meeting, AGU, Dec. 15-19, San Francisco, CA

Posted in Lab news, Meetings

New paper about how forests lose nitrogen through shallow groundwater flowpaths


This weir, a place in a stream where a wall controls the flow of water, measures stream flow and dissolved chemical exports from Watershed 3 at the Hubbard Brook Experimental Forest in New Hampshire, where the research took place (photo credit: JP Gannon).

In a paper published in the Proceedings of the National Academy of Sciences, McGuire working with a team from the Hubbard Brook Ecosystem Study found clear evidence of nitrogen loss through denitrification in isolated shallow groundwater patches in a small watershed. The findings were somewhat of a surprise because denitrification has been so difficult to measure at Hubbard Brook even though deposition and export relationships suggested that denitrification may have been a factor in the decline of nitrate concentrations observed in streamwater. The paper significance statement and abstract are below. The paper is also available now in PNAS early edition.


Denitrification is the most poorly understood process in the terrestrial N cycle. As a result, terrestrial N budgets are wildly unbalanced and our ability to address global nitrogen pollution is fundamentally constrained. Denitrification is controlled by multiple factors, often exhibiting extraordinary variation in time and space, especially in terrestrial environments. Temperate forests regularly receive much larger inputs of precipitation N than they export in streamwater. The fate of the rest has been elusive. We present stable isotope measurements revealing extensive evidence of denitrification from temper- ate-forest shallow groundwater in midsummer, even as concurrent measurements of streamwater show little sign of denitrification. These measurements support the importance of a disputed nitrogen removal process and its occurrence at a previously missed time and location.


Despite decades of measurements, the nitrogen balance of tem- perate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ15NNO3 and δ18ONO3) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments.

See also news stories by:


The Cornell Chronicle

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Welcome Ray!

Ray Lee

A new Ph.D. student, Ray Lee, joined our lab this week.  Ray recently completed his M.S. at San Diego State University in geography and studied environmental and resource economics and philosophy during his undergraduate program at UC-Davis.  Ray will be working on a project based at the Coweeta Hydrologic Lab in North Carolina.  Welcome to Blacksburg!

Posted in Lab news

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