Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks
Patrick J. McIntyre, James H. Thorne, Christopher R. Dolanc, Alan L. Flint, Lorraine E. Flint, Maggi Kelly, David D. Ackerly
2015, Proceedings of the National Academy of Sciences (112) 1458-1463
We document changes in forest structure between historical(1930s) and contemporary (2000s) surveys of California vegetation through comparisons of tree abundance and size across the state and within several ecoregions. Across California, tree density in forested regions increased by 30% between the two time periods, whereas forest biomass in the same...
River corridor science: Hydrologic exchange and ecological consequences from bedforms to basins
Judson Harvey, Michael Gooseff
2015, Water Resources Research (51) 6893-6922
Previously regarded as the passive drains of watersheds, over the past 50 years, rivers have progressively been recognized as being actively connected with off-channel environments. These connections prolong physical storage and enhance reactive processing to alter water chemistry and downstream transport of materials and energy. Here we propose river corridor...
Land subsidence in the San Joaquin Valley, California, USA, 2007-14
Michelle Sneed, Justin T. Brandt
2015, Proceedings of the International Association of Hydrological Sciences (372) 23-27
Rapid land subsidence was recently measured using multiple methods in two areas of the San Joaquin Valley (SJV): between Merced and Fresno (El Nido), and between Fresno and Bakersfield (Pixley). Recent land-use changes and diminished surface-water availability have led to increased groundwater pumping, groundwater-level declines, and land subsidence. Differential...
Numerical modeling of injection, stress and permeability enhancement during shear stimulation at the Desert Peak Enhanced Geothermal System
David Dempsey, Sharad Kelkar, Nick Davatzes, Stephen H. Hickman, Daniel Moos
2015, International Journal of Rock Mechanics and Mining Sciences (78) 190-206
Creation of an Enhanced Geothermal System relies on stimulation of fracture permeability through self-propping shear failure that creates a complex fracture network with high surface area for efficient heat transfer. In 2010, shear stimulation was carried out in well 27-15 at Desert Peak geothermal field, Nevada, by injecting cold water...
Observational changes to the natural flow regime in Lee Creek in relation to altered precipitation patterns and its implication for fishes
Michael R. Gatlin, James M. Long, Donald J. Turton
2015, Proceedings of the Oklahoma Academy of Science (95) 135-146
The natural flow regime is important for structuring streams and their resident ichthyofauna and alterations to this regime can have cascading consequences. We sought to determine if changes in hydrology could be attributed to changes in precipitation in a minimally altered watershed (Lee Creek). The stream flow regime was analyzed...
Origins and bioavailability of dissolved organic matter in groundwater
Yuan Shen, Francis H. Chapelle, Eric W. Strom, Ronald Benner
2015, Biogeochemistry (122) 61-78
Dissolved organic matter (DOM) in groundwater influences water quality and fuels microbial metabolism, but its origins, bioavailability and chemical composition are poorly understood. The origins and concentrations of dissolved organic carbon (DOC) and bioavailable DOM were monitored during a long-term (2-year) study of groundwater in a fractured-rock aquifer in the...
Quantifying and predicting fuels and the effects of reduction treatments along successional and invasion gradients in sagebrush habitats
Douglas J. Shinneman, David S. Pilliod, Robert Arkle, Nancy F. Glenn
2015, Report
Sagebrush shrubland ecosystems in the Great Basin are prime examples of how altered successional trajectories can create dynamic fuel conditions and, thus, increase uncertainty about fire risk and behavior. Although fire is a natural disturbance in sagebrush, post-fire environments are highly susceptible to conversion to an invasive grass-fire regime (often...
Quality assurance testing of acoustic doppler current profiler transform matrices
Brandy Armstrong, Janice M. Fulford, Kirk G. Thibodeaux
2015, Conference Paper, 2015 IEEE/OES Eleveth Current, Waves and Turbulence Measurement (CWTM)
The U.S. Geological Survey (USGS) Hydrologic Instrumentation Facility (HIF) is nationally responsible for the design, testing, evaluation, repair, calibration, warehousing, and distribution of hydrologic instrumentation in use within the USGS Water Mission Area (WMA). The HIF's Hydraulic Laboratory has begun routine quality assurance (QA) testing and documenting the performance of...
Drought monitoring and assessment: Remote sensing and modeling approaches for the Famine Early Warning Systems Network
Gabriel B. Senay, Naga Manohar Velpuri, Stefanie Bohms, Michael Budde, Claudia Young, James Rowland, James Verdin
2015, Book chapter
Drought monitoring is an essential component of drought risk management. It is usually carried out using drought indices/indicators that are continuous functions of rainfall and other hydrometeorological variables. This chapter presents a few examples of how remote sensing and hydrologic modeling techniques are being used to generate a suite of...
Vegetation composition, nutrient, and sediment dynamics along a floodplain landscape
Nancy B. Rybicki, Gregory E. Noe, Cliff R. Hupp, Myles Robinson
2015, River Systems (21) 109-123
Forested floodplains are important landscape features for retaining river nutrients and sediment loads but there is uncertainty in how vegetation influences nutrient and sediment retention. In order to understand the role of vegetation in nutrient and sediment trapping, we quantified species composition and the uptake of nutrients in plant material...
Discrete-storm water-table fluctuation method to estimate episodic recharge.
John R. Nimmo, Charles Horowittz, Lara Mitchell
2015, Groundwater (53) 282-292
We have developed a method to identify and quantify recharge episodes, along with their associated infiltration-related inputs, by a consistent, systematic procedure. Our algorithm partitions a time series of water levels into discrete recharge episodes and intervals of no episodic recharge. It correlates each recharge episode with a specific interval...
Soil ecology of a rock outcrop ecosystem: Abiotic stresses, soil respiration, and microbial community profiles in limestone cedar glades
Jennifer M. Cartwright, E. Kudjo Advised by Dzantor
2015, Thesis
Limestone cedar glades are a type of rock outcrop ecosystem characterized by shallow soil and extreme hydrologic conditions—seasonally ranging from xeric to saturated—that support a number of plant species of conservation concern. Although a rich botanical literature exists on cedar glades, soil biochemical processes and the ecology of soil microbial...
Variably-saturated groundwater modeling for optimizing managed aquifer recharge using trench infiltration
Victor M. Heilweil, Jerome Benoit, Richard W. Healy
2015, Hydrological Processes (29) 310-319
Spreading-basin methods have resulted in more than 130 million cubic meters of recharge to the unconfined Navajo Sandstone of southern Utah in the past decade, but infiltration rates have slowed in recent years because of reduced hydraulic gradients and clogging. Trench infiltration is a promising alternative technique for increasing recharge...
Pesticide concentrations in frog tissue and wetland habitats in alandscape dominated by agriculture
Kelly L. Smalling, Rebecca Reeves, Erin L. Muths, Mark W. Vandever, William A. Battaglin, Michelle Hladik, Clay L. Pierce
2015, Science of the Total Environment (502) 80-90
Habitat loss and exposure to pesticides are likely primary factors contributing to amphibian decline in agricultural landscapes. Conservation efforts have attempted to restore wetlands lost through landscape modifications to reduce contaminant loads in surface waters and providing quality habitat to wildlife. The benefits of this increased wetland area, perhaps especially...
Assessing the impacts of climate and land use and land cover change on the freshwater availability in the Brahmaputra River basin
Md Shahriar Pervez, Geoffrey M. Henebry
2015, Journal of Hydrology (3) 285-311
Study Region: Brahmaputra River basin in South Asia. Study Focus: The Soil and Water Assessment Tool was used to evaluate sensitivities and patterns in freshwater availability due to projected climate and land use changes in the Brahmaputra basin. The daily observed discharge at Bahadurabad station in Bangladesh was used to calibrate and validate...
Vegetation controls on weathering intensity during the last deglacial transition in southeast Africa
Sarah J. Ivory, Michael M. McGlue, Geoffrey S. Ellis, Anne-Marie Lézine, Andrew S. Cohen, Annie Vincens
2015, PLoS ONE (9)
Tropical climate is rapidly changing, but the effects of these changes on the geosphere are unknown, despite a likelihood of climatically-induced changes on weathering and erosion. The lack of long, continuous paleo-records prevents an examination of terrestrial responses to climate change with sufficient detail to answer questions about how systems...
Using scenario planning to evaluate the impacts of climate change on wildlife populations and communities in the Florida Everglades
Christopher P. Catano, Stephanie S. Romañach, James M. Beerens, Leonard G. Pearlstine, Laura A. Brandt, Kristen M. Hart, Frank J. Mazzotti, Joel C. Trexler
2015, Environmental Management (55) 807-823
It is uncertain how climate change will impact hydrologic drivers of wildlife population dynamics in freshwater wetlands of the Florida Everglades, or how to accommodate this uncertainty in restoration decisions. Using projections of climate scenarios for the year 2060, we evaluated how several possible futures could affect wildlife populations (wading...
User guide to Exploration and Graphics for RivEr Trends (EGRET) and dataRetrieval: R packages for hydrologic data
Robert M. Hirsch, Laura A. De Cicco
2015, Techniques and Methods 4-A10
Evaluating long-term changes in river conditions (water quality and discharge) is an important use of hydrologic data. To carry out such evaluations, the hydrologist needs tools to facilitate several key steps in the process: acquiring the data records from a variety of sources, structuring it in ways that facilitate the...
Development of a spatially universal framework for classifying stream assemblages with application to conservation planning for Great Lakes lotic fish communities
James E. McKenna Jr., Jeffrey S. Schaeffer, Jana S. Stewart, Michael T. Slattery
2015, Restoration Ecology (23) 167-178
Classifications are typically specific to particular issues or areas, leading to patchworks of subjectively defined spatial units. Stream conservation is hindered by the lack of a universal habitat classification system and would benefit from an independent hydrology-guided spatial framework of units encompassing all aquatic habitats at multiple spatial scales within...
Modeling long-term trends of chlorinated ethene contamination at a public supply well
Francis H. Chapelle, Leon J. Kauffman, Mark A. Widdowson
2015, Journal of the American Water Resources Association (51) 1-13
A mass-balance solute-transport modeling approach was used to investigate the effects of dense nonaqueous phase liquid (DNAPL) volume, composition, and generation of daughter products on simulated and measured long-term trends of chlorinated ethene (CE) concentrations at a public supply well. The model was built by telescoping a calibrated regional three-dimensional...
Hydrologic response to valley-scale structure in alpine headwaters
Anne A. Weekes, Christian E. Torgersen, David R. Montgomery, Andrea Woodward, Susan M. Bolton
2015, Hydrological Processes (29) 356-372
Few systematic studies of valley-scale geomorphic drivers of streamflow regimes in complex alpine headwaters have compared response between catchments. As a result, little guidance is available for regional-scale hydrological research and monitoring efforts that include assessments of ecosystem function. Physical parameters such as slope, elevation range, drainage area and bedrock...
Change in agricultural land use constrains adaptation of national wildlife refuges to climate change
Christopher M. Hamilton, Wayne E. Thogmartin, Volker C. Radeloff, Andrew J. Plantinga, Patricia J. Heglund, Sebastian Martinuzzi, Anna M. Pidgeon
2015, Environmental Conservation (42) 12-19
Land-use change around protected areas limits their ability to conserve biodiversity by altering ecological processes such as natural hydrologic and disturbance regimes, facilitating species invasions, and interfering with dispersal of organisms. This paper informs USA National Wildlife Refuge System conservation planning by predicting future land-use change on lands within 25...
Trend analyses with river sediment rating curves
Jonathan A. Warrick
2015, Hydrological Processes (29) 936-949
Sediment rating curves, which are fitted relationships between river discharge (Q) and suspended-sediment concentration (C), are commonly used to assess patterns and trends in river water quality. In many of these studies it is assumed that rating curves have a power-law form (i.e., C = aQb, where a and b...
Assessing stand water use in four coastal wetland forests using sapflow techniques: annual estimates, errors and associated uncertainties
Ken W. Krauss, Jamie A. Duberstein, William H. Conner
2015, Hydrological Processes (29) 112-127
Forests comprise approximately 37% of the terrestrial land surface and influence global water cycling. However, very little attention has been directed towards understanding environmental impacts on stand water use (S) or in identifying rates of S from specific forested wetlands. Here, we use sapflow techniques to address two separate but linked objectives:...
A 3400 year paleolimnological record of prehispanic human–environment interactions in the Holmul region of the southern Maya lowlands
David B. Wahl, Francisco Estrada-Belli, Lysanna Anderson
2015, Palaeogeography, Palaeoclimatology, Palaeoecology (379-380) 17-31
The timing, magnitude and drivers of late Holocene environmental change in the Holmul region of the southern Maya lowlands are examined by combining paleoenvironmental and archeological data. Environmental proxy analyses on a ~ 3350 cal yr lacustrine sediment record include pollen, charcoal, loss on ignition, magnetic suscep- tibility, and elemental...
