6/05/2017  |   09:00 - 09:15   |  302B

USING SPATIAL VARIABILITY IN CARBON AND NUTRIENT CHEMISTRY TO IDENTIFY DRIVERS AND DETECT CHANGE IN ARCTIC WATERSHEDS Dissolved organic carbon (DOC) and nutrient concentrations are increasing in rivers across the Arctic. Two hypotheses have been proposed to explain these trends: 1. distributed, top-down permafrost degradation, and 2. discrete, point-source delivery of DOC and nutrients from permafrost collapse features. While long-term monitoring at a single station cannot discriminate between these mechanisms, synoptic sampling of multiple points in the stream network could reveal the spatial structure of solute sources. In this context, we sampled carbon and nutrient chemistry in 119 subcatchments of three distinct Arctic watersheds (North Slope, Alaska). Subcatchments ranged from 0.1 to 80 km2, and included mountainous, tundra, and glacial-lake landscapes. We found that variance in solute concentrations between subcatchments collapsed at spatial scales between 1 to 20 km2, indicating a continuum of diffuse- and point-source dynamics, depending on solute and watershed characteristics (e.g. topography, vegetation, surficial geology). Spatially-distributed mass balance revealed conservative transport of DOC and nitrogen, but strong in-stream retention of phosphorus. We present new approaches to analyzing synoptic data for change detection and quantification of ecohydrological mechanisms in ecosystems in the Arctic and beyond.

Jay Zarnetske (Primary Presenter/Author), Department of Earth and Environmental Sciences, Michigan State University, jpz@msu.edu;


Benjamin Abbott ( Co-Presenter/Co-Author), Department of Earth and Environmental Sciences, Michigan State University, USA, benabbo@gmail.com;


William Breck Bowden ( Co-Presenter/Co-Author), University of Vermont, breck.bowden@uvm.edu;


Samuel P. Parker ( Co-Presenter/Co-Author), University of Vermont, samuel.parker@uvm.edu;


Frances Iannucci ( Co-Presenter/Co-Author), University of Alaska Fairbanks, fiannucci@alaska.edu;


Joshua Benes ( Co-Presenter/Co-Author), University of Vermont, Joshua.Benes@uvm.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   09:15 - 09:30   |  302B

PREDICTABILITY AND SELECTION OF HYDROLOGIC METRICS IN RIVERINE ECOHYDROLOGY A multitude of hydrologic metrics have been developed to describe natural flow regimes to quantify flow alteration that provide a hydrologic foundation for environmental flow standards. Many hydrologic metric estimation applications for streams require the use of models to predict natural values of hydrologic metrics. However, the error associated with these hydrologic metric estimation applications has not been previously evaluated. The primary goal of this study is to provide guidance to river scientists and water-resource managers with the selection, use and interpretation of hydrologic metrics for stream classification and hydroecological investigations of river ecosystems. We evaluated the predictability of 612 hydrologic metrics using statistical models, and we also examined how the predictability varied among unique components of the flow regime. Roughly 40% out of 612 hydrologic metrics examined can be reliably predicted. The predictable metrics were disproportionately represented in five flow components: asymmetry, seasonality, magnitude, variability, and average monthly flows. Most metrics that represent extreme hydrologic events could not be reliably predicted. Roughly two-thirds of the evaluated hydrologic metrics were incalculable or highly biased at intermittent streams due to logarithmic transformations or scaling by other hydrologic metrics.

Ken Eng (Primary Presenter/Author), U.S. Geological Survey, keng@usgs.gov;


Ted Grantham ( Co-Presenter/Co-Author), University of California, Berkeley, tgrantham@berkeley.edu;


Daren Carlisle ( Co-Presenter/Co-Author), U.S. Geological Survey, dcarlisle@usgs.gov;


David Wolock ( Co-Presenter/Co-Author), U.S. Geological Survey, dwolock@usgs.gov;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   09:30 - 09:45   |  302B

Wetland Networks and Graph Theory Wetlands are ubiquitous topographic depressions and their distribution can be (statistically) predicted in our fractal world. They influence soil moisture and hydrologic connectivity, and in turn the climate-soil-vegetation-fauna interactions. As such, they play essential roles across environmental scales, from ecosystems to biogeochemical processes. As wetlands function as nodes in a connected landscape, we use network tools to analyze their impact on hydroecological processes. In this presentation, we will show scenarios of climate and groundwater interactions and their impact on the dispersal and survival of species and communities with different adaptive strategies. We then use our approach to predict the likelihood of finding a species in a wetlandscape at a particular time given its hydroclimatic state, as well as steady state probability densities across the waterscape. We also show the validity of our approach by comparing model predictions to survey data of vegetation and amphibians.

Antoine Aubeneau (Primary Presenter/Author), Purdue University, aubeneau@gmail.com;


Leonardo Bertassello ( Co-Presenter/Co-Author), Purdue University, leonardo.bertassello@gmail.com;


Jason Hoverman ( Co-Presenter/Co-Author), Purdue University, jhoverm@purdue.edu;


Suresh Rao ( Co-Presenter/Co-Author), Purdue University, SureshRao@purdue.edu ;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   09:45 - 10:00   |  302B

HYDROLOGIC GEOMETRY OF THE HYPORHEIC ZONE Expansive hyporheic zones often govern the transient storage dynamics of gravel-bedded rivers. The residence time distribution (RTD) of transient storage (TS) is a probability distribution function describing the likelihood that a water molecule entering TS at time 0 will exit from TS at some future time, t. The RTD follows a power law across time scales from seconds to years. To create a quantitative conceptual model of hyporheic hydrology and associated TS, we partition the hyporheic zone into multiple TS zones defined by hyporheic water age (time since entering the hyporheic zone). The distribution of hydrologic storage and exchange rates among the multiple hyporheic TS zones is described by the power-law exponent and total volume of the hyporheic zone. By calculating the flux rates, volumes, and flow-path lengths associated with each hyporheic TS zone, we provide both a concrete basis for conceptualizing water storage and flux within the hyporheic zone, as well as the mathematical foundation for scalable simulation of hyporheic hydrology, water temperature, and biogeochemistry in stream networks.

Geoffrey Poole (Primary Presenter/Author), Montana State University, Montana Institute on Ecosystems, gpoole@montana.edu ;


Katie Fogg ( Co-Presenter/Co-Author), Montana State University, s.katie.fogg@gmail.com;


Byron Amerson ( Co-Presenter/Co-Author), Montana State University, byron.amerson@gmail.com;


Ann Marie Reinhold ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, reinhold@montana.edu;


Sam Carlson ( Co-Presenter/Co-Author), Montana State University, sam.p.carlson@gmail.com;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   10:00 - 10:15   |  302B

A COMPARISON OF CHANNEL SHADE AND HYPORHEIC EXCHANGE ON SEASONAL PATTERNS OF STREAM TEMPERATURE Channel shading and hyporheic exchange both have the potential to damp the amplitude of daily and annual stream temperature cycles, but operate via different mechanisms. Because of these mechanistic differences, subtle to substantial shifts in the timing and magnitude of temperature damping in the stream channel may exist. Therefore, we compared the daily and seasonal effects of channel shading versus hyporheic exchange using a reach-scale model of channel temperature that incorporates atmospheric heat exchange and a hydrologically-accurate representation of the hyporheic zone. In summer, the magnitude of seasonal channel cooling associated with an expansive, coarse-grained hyporheic zone was similar to shading effects. However, the differences between shading and hyporheic exchange effects were most pronounced in the winter when channel warming associated with hyporheic exchange was substantially greater than warming associated with shade. Whereas shade effects are largely limited to summer, hyporheic exchange showed substantial influences on stream temperatures throughout the year. Understanding the differences between how hyporheic exchange and shade influence stream temperature has the potential to guide restoration and management decisions in thermally degraded streams.

Katie Fogg (Primary Presenter/Author), Montana State University, s.katie.fogg@gmail.com;


Geoffrey Poole ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, gpoole@montana.edu ;


Scott O'Daniel ( Co-Presenter/Co-Author), Confederated Umatilla Tribes, scottodaniel@ctuir.org;


Ann Marie Reinhold ( Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems, reinhold@montana.edu;


Presentation:
This presentation has not yet been uploaded.

6/05/2017  |   10:15 - 10:30   |  302B

PLASTICITY IN TIMING OF HYDROLOGIC SPAWNING CUES FOR THE FOOTHILL YELLOW-LEGGED FROG (RANA BOYLII) UNDER MEDITERRANEAN CLIMATE EXTREMES IN SIERRA NEVADA RIVERS Rana boylii (Foothill Yellow-legged Frog) requires specific hydrologic cues to start spawning (oviposition). These hydrologic cues are similar across a wide geographic range, despite inter-annual variability in runoff timing inherent to a Mediterranean climate. For R. boylii, plasticity in spawning timing may be viewed as a predictable response to consistent hydrologic cues, such as flow timing, rate of receding spring snowmelt-runoff, and increasing water temperature. We show data demonstrating differences in inter-annual spawning timing in R. boylii between wet and dry years, including some of the earliest and latest oviposition documented in the Sierra Nevada. R. boylii shows high plasticity in timing of oviposition (in days) inter-annually, yet oviposition remains strongly correlated with the rate of the natural spring snowmelt recession in the Sierra Nevada and the minimum average weekly water temperature. A summary of over 10 years of spawning data for R. boylii across California shows the range in timing can vary by four months, from early March to early July. Better understanding of the hydrologic cues used by a lotic indicator species may help improve flow management efforts to mimic naturally functioning flow regimes.

Ryan Peek (Primary Presenter/Author), University of California, Davis, rapeek@ucdavis.edu;


Sarah Yarnell ( Co-Presenter/Co-Author), University of California, Davis, smyarnell@ucdavis.edu;


Presentation:
This presentation has not yet been uploaded.