A conceptual framework for dryland aeolian sediment transport along the grassland–forest continuum: Effects of woody plant canopy cover and disturbance
D.D. Breshears, J.J. Whicker, C.B. Zou, J.P. Field, Craig D. Allen
2009, Geomorphology (105) 28-38
Aeolian processes are of particular importance in dryland ecosystems where ground cover is inherently sparse because of limited precipitation. Dryland ecosystems include grassland, shrubland, savanna, woodland, and forest, and can be viewed collectively as a continuum of woody plant cover spanning from grasslands with no woody plant cover up...
Late Pleistocene paleohydrology near the boundary of the Sonoran and Chihuahuan Deserts, southeastern Arizona, USA
Jeffery S. Pigati, Jordon E. Bright, Timothy M. Shanahan, Shannon Mahan
2009, Quaternary Science Reviews (28) 286-300
Ground-water discharge (GWD) deposits form in arid environments as water tables rise and approach or breach the ground surface during periods of enhanced effective precipitation. Where preserved, these deposits contain information on the timing and elevation of past ground-water fluctuations. Here we report on the investigation of a series of...
Water balance dynamics in the Nile Basin
Gabriel B. Senay, Kwabena Asante, Guleid A. Artan
2009, Hydrological Processes (23) 3675-3681
Understanding the temporal and spatial dynamics of key water balance components of the Nile River will provide important information for the management of its water resources. This study used satellite-derived rainfall and other key weather variables derived from the Global Data Assimilation System to estimate and map the distribution of...
Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow
M. Hutnak, S. Hurwitz, S. E. Ingebritsen, P. A. Hsieh
2009, Journal of Geophysical Research B: Solid Earth (114)
Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have...
Assigning land use to supply wells for the statistical characterization of regional groundwater quality: Correlating urban land use and VOC occurrence
T.D. Johnson, K. Belitz
2009, Journal of Hydrology (370) 100-108
Many national and regional groundwater studies have correlated land use "near" a well, often using a 500 m radius circle, with water quality. However, the use of a 500 m circle may seem counterintuitive given that contributing areas are expected to extend up-gradient from wells, and not be circular in...
First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach
B.A. Ebel, B.B. Mirus, C.S. Heppner, J.E. VanderKwaak, K. Loague
2009, Hydrological Processes (23) 1949-1959
Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced...
Mercury sources, distribution, and bioavailability in the North Pacific Ocean: Insights from data and models
E.M. Sunderland, D. P. Krabbenhoft, J.W. Moreau, S.A. Strode, W.M. Landing
2009, Global Biogeochemical Cycles (23)
Fish harvested from the Pacific Ocean are a major contributor to human methylmercury (MeHg) exposure. Limited oceanic mercury (Hg) data, particularly MeHg, has confounded our understanding of linkages between sources, methylation sites, and concentrations in marine food webs. Here we present methylated (MeHg and dimethylmercury (Me2Hg)) and total Hg concentrations...
Introduction to special section on impacts of land use change on water resources
David A. Stonestrom, Bridget R. Scanlon, Lu Zhang
2009, Water Resources Research (45)
Changes in land use have potentially large impacts on water resources, yet quantifying these impacts remains among the more challenging problems in hydrology. Water, food, energy, and climate are linked through complex webs of direct and indirect effects and feedbacks. Land use is undergoing major changes due not only to...
Hydrologic characterization of desert soils with varying degrees of pedogenesis: 2. Inverse modeling for eff ective properties
B.B. Mirus, K. S. Perkins, J. R. Nimmo, K. Singha
2009, Vadose Zone Journal (8) 496-509
To understand their relation to pedogenic development, soil hydraulic properties in the Mojave Desert were investi- gated for three deposit types: (i) recently deposited sediments in an active wash, (ii) a soil of early Holocene age, and (iii) a highly developed soil of late Pleistocene age. Eff ective parameter values...
Hydrologic connectivity between landscapes and streams: Transferring reach‐ and plot‐scale understanding to the catchment scale
Kelsey G. Jencso, Brian L. McGlynn, Michael N. Gooseff, Steven M. Wondzell, Kenneth E. Bencala, Lucy A. Marshall
2009, Water Resources Research (45)
The relationship between catchment structure and runoff characteristics is poorly understood. In steep headwater catchments with shallow soils the accumulation of hillslope area (upslope accumulated area (UAA)) is a hypothesized first‐order control on the distribution of soil water and groundwater. Hillslope‐riparian water table connectivity represents the linkage between the dominant...
Mercury cycling in stream ecosystems. 1. Water column chemistry and transport
M. E. Brigham, D.A. Wentz, G. R. Aiken, D. P. Krabbenhoft
2009, Environmental Science & Technology (43) 2720-2725
We studied total mercury (THg) and methylmercury (MeHg) in eight streams, located in Oregon, Wisconsin, and Florida, that span large ranges in climate, landscape characteristics, atmospheric Hg deposition, and water chemistry. While atmospheric deposition was the source of Hg at each site, basin characteristics appeared to mediate...
Hydrologic characterization of desert soils with varying degrees of pedogenesis: 1. field experiments evaluating plant-relevant soil water behavior
John R. Nimmo, Kim S. Perkins, Kevin M. Schmidt, David M. Miller, Jonathan D. Stock, Kamini Singha
2009, Vadose Zone Journal (8) 480-495
To assess the eff ect of pedogenesis on the soil moisture dynamics infl uencing the character and quality of ecological habitat, we conducted infi ltration and redistribution experiments on three alluvial deposits in the Mojave National Preserve: (i) recently deposited active wash sediments, (ii) a soil of early Holocene age,...
Biodegradation of 17β-estradiol, estrone and testosterone in stream sediments
Paul M. Bradley, Larry B. Barber, Francis H. Chapelle, James L. Gray, Dana W. Kolpin, Peter B. McMahon
2009, Environmental Science & Technology (43) 1902-1910
Biodegradation of 17β-estradiol (E2), estrone (E1), and testosterone (T) was investigated in three wastewater treatment plant (WWTP) affected streams in the United States. Relative differences in the mineralization of [4-14C] substrates were assessed in oxic microcosms containing saturated sediment or water-only from locations upstream and downstream of the WWTP outfall...
Sources of uncertainty in flood inundation maps
J. D. Bales, C. R. Wagner
2009, Journal of Flood Risk Management (2) 139-147
Flood inundation maps typically have been used to depict inundated areas for floods having specific exceedance levels. The uncertainty associated with the inundation boundaries is seldom quantified, in part, because all of the sources of uncertainty are not recognized and because data available to quantify uncertainty seldom are available. Sources...
Ground and surface temperature variability for remote sensing of soil moisture in a heterogeneous landscape
M.A. Giraldo, D. Bosch, M. Madden, L. Usery, M. Finn
2009, Journal of Hydrology (368) 214-223
At the Little River Watershed (LRW) heterogeneous landscape near Tifton Georgia US an in situ network of stations operated by the US Department of Agriculture-Agriculture Research Service-Southeast Watershed Research Lab (USDA-ARS-SEWRL) was established in 2003 for the long term study of climatic and soil biophysical processes. To develop an accurate...
Reducing streamflow forecast uncertainty: Application and qualitative assessment of the upper klamath river Basin, Oregon
L.E. Hay, G.J. McCabe, M.P. Clark, J. C. Risley
2009, Journal of the American Water Resources Association (45) 580-596
The accuracy of streamflow forecasts depends on the uncertainty associated with future weather and the accuracy of the hydrologic model that is used to produce the forecasts. We present a method for streamflow forecasting where hydrologic model parameters are selected based on the climate state. Parameter sets for a hydrologic...
Temporal response of hydraulic head, temperature, and chloride concentrations to sea-level changes, Floridan aquifer system, USA
J.D. Hughes, H. Leonard Vacher, W. E. Sanford
2009, Hydrogeology Journal (17) 793-815
Three-dimensional density-dependent flow and transport modeling of the Floridan aquifer system, USA shows that current chloride concentrations are not in equilibrium with current sea level and, second, that the geometric configuration of the aquifer has a significant effect on system responses. The modeling shows that hydraulic head equilibrates first, followed...
The use of fluoride as a natural tracer in water and the relationship to geological features: Examples from the Animas River Watershed, San Juan Mountains, Silverton, Colorado
Dana J. Bove, Katherine Walton-Day, Briant A. Kimball
2009, Geochemistry: Exploration, Environment, Analysis (9) 125-138
Investigations within the Silverton caldera, in southwestern Colorado, used a combination of traditional geological mapping, alteration-assemblage mapping, and aqueous geochemical sampling that showed a relationship between geological and hydrologic features that may be used to better understand the provenance and evolution of the water. Veins containing fluorite, huebnerite, and elevated...
Evaluation of irrigation canal networks to assess stream connectivity in a watershed
M.E. Colvin, C.M. Moffitt
2009, River Research and Applications (25) 486-496
We used digital data sets, aerial photos and direct field observations in a geographical information system to evaluate the stream habitat in an Idaho watershed affected by agriculture. We found that the scale of the digital data sets affected the outcome of the assessment due to the presence of dewatered...
Utilizing chromophoric dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: A case study of the Yukon River, Alaska
R.G.M. Spencer, G. R. Aiken, K.D. Butler, M.M. Dornblaser, Robert G. Striegl, P.J. Hernes
2009, Geophysical Research Letters (36)
[1] The quality and quantity of dissolved organic matter (DOM) exported by Arctic rivers is known to vary with hydrology and this exported material plays a fundamental role in the biogeochemical cycling of carbon at high latitudes. We highlight the potential of optical measurements to examine DOM...
Reproductive health of bass in the potomac, USA, drainage: Part 2. Seasonal occurrence of persistent and emerging organic contaminants
D.A. Alvarez, W.L. Cranor, S.D. Perkins, V.L. Schroeder, L. R. Iwanowicz, R.C. Clark, C.P. Guy, A.E. Pinkney, V. S. Blazer, J.E. Mullican
2009, Environmental Toxicology and Chemistry (28) 1084-1095
The seasonal occurrence of organic contaminants, many of which are potential endocrine disruptors, entering the Potomac River, USA, watershed was investigated using a two-pronged approach during the fall of 2005 and spring of 2006. Passive samplers (semipermeable membrane device and polar organic chemical integrative sampler [POCIS]) were deployed in tandem...
N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society
K. A. Thorn, L.G. Cox
2009, Organic Geochemistry (40) 484-499
The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS 15N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil...
Respiratory arsenate reductase as a bidirectional enzyme
C. Richey, P. Chovanec, S.E. Hoeft, R.S. Oremland, P. Basu, J.F. Stolz
2009, Biochemical and Biophysical Research Communications (382) 298-302
The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative...
Evaluation of a moderate resolution, satellite-based impervious surface map using an independent, high-resolution validation data set
J. W. Jones, T. Jarnagin
2009, Journal of Hydrologic Engineering (14) 369-376
Given the relatively high cost of mapping impervious surfaces at regional scales, substantial effort is being expended in the development of moderate-resolution, satellite-based methods for estimating impervious surface area (ISA). To rigorously assess the accuracy of these data products high quality, independently derived validation data are needed. High-resolution data were...
Trends in streamflow in the Yukon River Basin from 1944 to 2005 and the influence of the Pacific Decadal Oscillation
T. P. Brabets, Michelle Ann Walvoord
2009, Journal of Hydrology (371) 108-119
Streamflow characteristics in the Yukon River Basin of Alaska and Canada have changed from 1944 to 2005, and some of the change can be attributed to the two most recent modes of the Pacific Decadal Oscillation (PDO). Seasonal, monthly, and annual stream discharge data from 21 stations in the Yukon...
