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Diurnal cycles in snow‐fed streams provide a useful technique for measuring the time it takes water to travel from the top of the snowpack, where snowmelt typically peaks in the afternoon, to the river gauge, where the daily maximum flows may arrive many hours later. Hourly stage measurements in nested...

The increasing complexity of water- and environmental-resource problems require modeling approaches that incorporate knowledge from a broad range of scientific and software disciplines. To address this need, the U.S. Geological Survey (USGS) has developed the Modular Modeling System (MMS). MMS is an integrated system of computer software for model development,...

During 1902 to 1906 as a soil physicist at the USDA Bureau of Soils (BOS), Edgar Buckingham originated the concepts of matric potential, soil–water retention curves, specific water capacity, and unsaturated hydraulic conductivity (K) as a distinct property of a soil. He applied a formula equivalent to Darcy's law (though...

The fate of antibiotics that bind to riverine sediment is not well understood. A solution used in geochemical extraction schemes to determine loosely bound species in sediments, 1 M MgCl2 (pH 8), was chosen to determine loosely bound, and potentially bioavailable, tetracycline antibiotics (TCs), including oxytetracycline (5-OH tetracycline)...

Experiments were conducted to evaluate the impact of groundwater chemistry and travel distance on the transport and fate behavior of PRD-1, a bacteriophage employed as a surrogate tracer for pathogenic enteric viruses. The experiments were conducted in the unconfined aquifer at the United States...

The potential introduction of N-nitrosodimethylamine (NDMA) into groundwater during water reclamation activities poses a significant risk to groundwater drinking supplies. Greater than 54% biodegradation of N-[methyl-14C]NDMA to 14CO2 or to 14CO2 and 14CH4 was observed in soil from a water reclamation facility under oxic or anoxic conditions, respectively. Likewise, biodegradation...

No abstract available. ...

After reductive immobilization of uranium, the element may be oxidized and remobilized in the presence of nitrate by the activity of dissimilatory nitrate-reducing bacteria. We examined controls on microbially mediated nitrate-dependent U(IV) oxidation in landfill leachate-impacted subsurface sediments. Nitrate-dependent U(IV)-oxidizing bacteria were at least two orders of magnitude less numerous...

Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in...

Wavelet analysis is a powerful tool with which to analyse the hydrologic effects of dam construction and operation on river systems. Using continuous records of instantaneous discharge from the Lees Ferry gauging station and records of daily mean discharge from upstream tributaries, we conducted wavelet analyses of the hydrologic structure...

A methodology to estimate in-bank river discharge exclusively from remotely sensed hydraulic data is developed. Water-surface width and maximum channel width measured from 26 aerial and digital orthophotos of 17 single channel rivers and 41 SAR images of three braided rivers were coupled with channel slope data obtained from topographic...

The undulating, warped, and densely fractured surfaces of highland regions east of Valles Marineris (located north of the eastern Aureum Chaos, east of the Hydraotes Chaos, and south of the Hydaspis Chaos) resulted from extensional surface warping related to ground subsidence, caused when pressurized water confined in subterranean caverns was...

Seepage losses along numerous mountain front streams that discharge intermittently onto alluvial fans and piedmont alluvial plains are an important source of groundwater in the Basin and Range Province of the Western United States. Determining the distribution of seepage loss along mountain front streams is important when assessing groundwater resources...

A battery powered submersible chemical analyzer, the Zn-DigiScan (Zn Digital Submersible Chemical Analyzer), has been developed for near real-time, in situ monitoring of zinc in aquatic systems. Microprocessor controlled solenoid pumps propel sample and carrier through an anion exchange column to separate zinc from interferences, add colorimetric reagents, and propel...

Depletion of calcium from forest soils has important implications for forest productivity and health. Ca is available to fine feeder roots from a number of soil organic and mineral sources, but identifying the primary source or changes of sources in response to environmental change is problematic. We used strontium...

To determine whether NO3− concentration pulses in surface water in early spring snowmelt discharge are due to atmospheric NO3−, we analyzed stream δ15N-NO3− and δ18O-NO3− values between February and June of 2001 and 2002 and compared them to those of throughfall, bulk precipitation, snow, and groundwater. Stream total Al, DOC and Si...

[1] Geophysical imaging has traditionally provided qualitative information about geologic structure; however, there is increasing interest in using petrophysical models to convert tomograms to quantitative estimates of hydrogeologic, mechanical, or geochemical parameters of interest (e.g., permeability, porosity, water content, and salinity). Unfortunately, petrophysical estimation based on tomograms...

We have used a total of 496 sample sites to calibrate a simple regression model for calculating dissolved inorganic nutrient fluxes via runoff to the ocean. The regression uses the logarithms of runoff and human population as the independent variables and estimates the logarithms of dissolved inorganic nitrogen and phosphorus...

Molecular techniques are valuable tools that can improve our understanding of the structure of microbial communities. They provide the ability to probe for life in all niches of the biosphere, perhaps even supplanting the need to cultivate microorganisms or to conduct ecophysiological investigations. However, an overemphasis and strict dependence on...

A broad range of organic compounds is recognized as environmentally relevant for their potential adverse effects on human and ecosystem health. This method was developed to better determine the distribution of 61 compounds that are typically associated with industrial and household waste as...

No abstract available....

Natural unsaturated-zone gas profiles at the U.S. Geological Survey's Amargosa Desert Research Site, near Beatty, Nevada, reveal the presence of two physically and isotopically distinct CO2 sources, one shallow and one deep. The shallow source derives from seasonally variable autotrophic and heterotrophic respiration in the root zone. Scanning electron micrograph...

Some of the largest unit discharge flood peaks in the stream gaging records of the U.S. Geological Survey (USGS) have occurred in Puerto Rico. Many of these flood peaks are associated with tropical cyclones. Hurricane Georges, which passed directly over the island on 21–22 September 1998, produced record flood peaks...

As part of a multidisciplinary investigation designed to assess the implications of coal-bed methane development on water resources for the Powder River Basin of southeastern Montana, six wells were drilled through Paleocene-age coal bedsalong a 31-km east–west transect within the Tongue River drainage basin. Analysis of geophysical logs obtained...

Accurate estimation of snow mass is important for the characterization of the hydrological cycle at different space and time scales. For effective water resources management, accurate estimation of snow storage is needed. Conventionally, snow depth is measured at a point, and in order to monitor snow depth in a temporally...