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Gary W. Zellweger

Publications and source records attributed to Gary W. Zellweger.

12 recordsLinked to original sources
USGS2010

Influence of diurnal variations in stream temperature on streamflow loss and groundwater recharge

We demonstrate that for losing reaches with significant diurnal variations in stream temperature, the effect of stream temperature on streambed seepage is a major factor contributing to reduced afternoon streamflows. An explanation is based on the effect of stream temperature on the hydraulic conductivity of the streambed, which can be expected to double in the 0° to 25°C temperature range. Results are presented for field experiments in which stream discharge and temperature were continuously measured for several days over losing reaches at St. Kevin Gulch, Colorado, and Tijeras Arroyo, New Mexico. At St. Kevin Gulch in July 1991, the diurnal stream temperature in the 160-m study reach ranged from about 4° to 18°C, discharges ranged from 10 to 18 L/s, and streamflow loss in the study reach ranged from 2.7 to 3.7 L/s. On the basis of measured stream temperature variations, the predicted change in conductivity was about 38%; the measured change in stream loss was about 26%, suggesting that streambed temperature varied less than the stream temperature. At Tijeras Arroyo in May 1992, diurnal stream temperature in the 655-m study reach ranged from about 10° to 25°C and discharge ranged from 25 to 55 L/s. Streamflow loss was converted to infiltration rates by factoring in the changing stream reach surface area and streamflow losses due to evaporation rates as measured in a hemispherical evaporation chamber. Infiltration rates ranged from about 0.7 to 2.0 m/d, depending on time and location. Based on measured stream temperature variations, the predicted change in conductivity was 29%; the measured change in infiltration was also about 27%. This suggests that high infiltration rates cause rapid convection of heat to the streambed. Evapotranspiration losses were estimated for the reach and adjacent flood plain within the arroyo. On the basis of these estimates, only about 5% of flow loss was consumed via stream evaporation and stream-side evapotranspiration, indicating that 95% of the loss within the study reach represented groundwater recharge.

Water Resources Research↗
USGS2010

Variation of rain chemistry during storms at two sites in northern California

The chemical composition of rainfall at Menlo Park, on San Francisco Bay, is compared with rainfall at Petrolia, which is near the coast about 500 km north of San Francisco. Sequential samples representing 1.35 to 5.4 mm of rain were collected from November 1971 to January 1972. At rural Petrolia the Cl:Na ratio was that of seawater for Cl concentrations ranging from 0.02 to 38 mg/l. In metropolitan Menlo Park the Cl:Na ratio in rain closely approximated that in seawater above about 0.5 mg/l Cl, but at lower Cl concentrations the ratio exceeded that in seawater, a fact attributed to the presence of anthropogenic Cl. Other constituents dissolved in Menlo Park rain (along with their concentration ranges in milligrams per liter), and believed to be derived in part from anthropogenic sources, were Ca (0.01–1.07), Mg (<0.01–1.08), Pb (0.003–0.035), Zn (0.002–0.013), Mn (0.0001–0.0057), Cu (0.0008–0.0024), NO 3 ‐N (0.02–0.54), and Br (<0.01–0.12). The range of p H values was smaller in the rural than in the metropolitan areas; average H + activity corresponded to a p H of 5.1 to 5.2 in both areas. At Petrolia, p H decreased with increased dissolved salts in rainfall, but no relation between p H and dissolved salts was evident at Menlo Park.

California↗
USGS2010

Kinetic analysis of strontium and potassium sorption onto sands and gravels in a natural channel

A kinetic, first-order mass transfer model was used to describe the sorption of strontium onto sand- and gravel-sized streambed sediments. Rate parameters, empirically determined for strontium, allowed for the prediction of potassium sorption with moderate success. The model parameters varied significantly with particle size. The sorption data were collected during an experimental injection of several elements into a small mountain pool-and-riffle stream. The sorption process onto sand- and gravel-sized sediment was relatively slow compared to changes in the dissolved concentrations.

Water Resources Research↗
USGS2010

Interactions of solutes and streambed sediment: 1. An experimental analysis of cation and anion transport in a mountain stream

An experimental injection was performed to study the transport of stream water solutes under conditions of significant interaction with streambed sediments in a mountain pool-and-riffle stream. Experiments were conducted in Little Lost Man Creek, Humboldt County, California, in a period of low flow duringwhich only a part of the bank-full channel held active surface flow. The injection of chloride and several trace cations lasted 20 days. In this report we discuss the results of the first 24 hours of the injection and survey the results of the first 10 days. Solute-streambed interactions of two types were observed. First, the physical transport of the conservative tracer, chloride, was affected by intergravel flow and stagnant watt, zones created by the bed relief. Second, the transport of the cations (strontium, potassium, and lithium) was appreciably modified by sorption onto streambed sediment. In the stream the readily observable consequence of the solute-streambed interactions was an attenuation of the dissolved concentration of each of the tracers. The attenuation in the stream channel occurred concurrently with the storage of tracers in the streambed via both physical and chemical processes. All tracers were subsequently present in shallow wells dug several meters from the wetted part of the channel. Sediment samples collected approximately 3 weeks after the start of the injection contained increased concentrations of the injected cations.

California↗
USGS2010

Characterization of transport in an acidic and metal-rich mountain stream based on a lithium tracer injection and simulations of transient storage

Physical parameters characterizing solute transport in the Snake River (an acidic and metal-rich mountain stream near Montezuma, Colorado) were variable along a 5.2-km study reach. Stream cross-sectional area and volumetric inflow each varied by a factor of 3. Because of transient storage, the residence time of injected tracers in the Snake River was longer than would be calculated by consideration of convective travel time alone. Distributed inflows along the stream were a significant source of in-stream chemical variations. These transport characteristics of the Snake River were established on the basis of the assumption of lithium as an ideally conservative tracer and use of simulations of advection, dispersion, and transient storage. Evaluations of the validity of this combined tracer and simulation approach lend confidence to the estimation of the physical transport parameters, but further development is warranted for methods of onsite transport experimentation in hydrologically complex, chemically reactive environments.

Water Resources Research↗
USGS2007

Rhodamine-WT dye losses in a mountain stream environment

A significant fraction of rhodamine WT dye was lost during a short term multitracer injection experiment in a mountain stream environment. The conservative anion chloride and the sorbing cation lithium were concurrently injected. In-stream rhodamine WT concentrations were as low as 45 percent of that expected, based on chloride data. Concentration data were available from shallow‘wells’dug near the stream course and from a seep of suspected return flow. Both rhodamine WT dye and lithium were nonconservative with respect to the conservative chloride, with rhodamine WT dye closely following the behavior of the sorbing lithium. Nonsorption and sorption mechanisms for rhodamine WT loss in a mountain stream were evaluated in laboratory experiments. Experiments evaluating nonsorption losses indicated minimal losses by such mechanisms. Laboratory experiments using sand and gravel size streambed sediments show an appreciable capacity for rhodamine WT sorption. The detection of tracers in the shallow wells and seep indicates interaction between the stream and the flow in the surrounding subsurface, intergravel water, system. The injected tracers had ample opportunity for intimate contact with materials shown in the laboratory experiments to be potentially sorptive. It is suggested that in the study stream system, interaction with streambed gravel was a significant mechanism for the attenuation of rhodamine WT dye (relative to chloride).

Journal of the American Water Resources Associatio↗
USGS2007

Dynamics of added nitrate and phosphate compared in a northern California woodland stream

Injections of NO 3 and PO 4 were made during September 1975 into Little Lost Man Creek, a small pristine stream in Redwood National Park, California. Chloride, a conservative constituent, was added in a known ratio to the nutrients. Nutrient loss at a downstream point was calculated using concentration of added Cl as a reference. Nitrate nitrogen (NO 3 ‐N), added for 4 h, reached 920 μg/1 (above 5 μg/1 background) just below the injection point, but increased only to 405 μg/1 at 310 m downstream. The concentration decrease was attributed to dispersion and to uptake by stream biota. Percent of NO 3 ‐N lost decreased with increasing concentration of NO 3 ‐N. Phosphate phosphorus (PO 4 ‐P) was added a week after the NO 3 ‐N for 3 h, causing a concentration increase of 296 μg/1 (above 13 μg/1 background) just below the injection point, of 161 μg/1 at 90 m downstream, and of 98 μg/1 at 310 m. Percent loss of PO 4 ‐P at downstream sites increased with increasing PO 4 ‐P concentration and also for a short period after peak concentration occurred, but then decreased as PO 4 ‐P concentration continued decreasing. Differences in stream response to added NO 3 ‐N and PO 4 ‐P are attributed to differing rates of reaction with biota and differing degrees of interaction with abiotic stream solids.

California↗
USGS1990

In situ retention-transport response to nitrate loading and storm discharge in a third-order stream

Nitrate retention was assayed in a 264-m reach of a third-order stream, Little Lost Man Creek, Humboldt County, California, USA. Nitrate budgets (24-48 hours) were calculated under background conditions, and during four other intervals of modified nitrate concentration caused by nutrient amendment or storm-enhanced discharge. Under background, low-flow conditions, the reach was a source of nitrate to downstream communities. Retention during the first 36 hours of nitrate amendment was dominated by storage in the hyporheic zone and later by biotic uptake as storage zones became saturated (plateau concentration). The increase in net retention caused by increased nitrate concentration decreased output/input (O/I) ratio from 1.11 before amendment to 0.61 after 36 hours, and to 0.86 after transient storage zones were filled. Dilution, caused by a nearly four-fold increase in discharge, increased biotic retention and also export as previously stored nitrate leached from the hyporheic zone into the channel. Nitrate continued to leach from the hyporheic zone seven days after the amendment ended. This type of response may enhance biotic nutrient cycling by providing waters of higher nutrient concentration to partially scoured epilithic surfaces following reset of the benthic community by a major storm.

California↗
USGS1989

Retention and transport of nutrients in a third-order stream: Channel processes

Chloride was injected as a conservative tracer with nitrate to examine nitrate retention (storage plus biotic uptake) and transport in a 327—m reach of a third—order stream draining a forested basin in northwestern California. Prior to injections, diel patterns of nutrient concentrations were measured under background conditions. Nitrate concentration of stream water increased downstream, indicating that the reach was a source of dissolved inorganic nitrogen to downstream communities under background, low—flow conditions, despite uptake by photoautotrophs. At the onset of continuous solute injection over a 10—d period, timing the passage of the solute front indicated that storage dominated nitrate retention. Instantaneous concentration differences at the base of the reach at hour 24 indicated that biotic uptake accounted for 13% of the nitrate amendment while hydrologic storage constituted 29%. Corrected for groundwater dilution (11.7%), saturation of the stream's channel and hyporheic zones was not complete until 6.8 d of continuous injection. By day 3 nitrate retention was dominated by biotic processes. Biotic uptake was greatest during daylight hours indicating retention by photoautotrophs, but also occurred during darkness. After 10 d of continuous injection, mass balance calculations indicated that 29% of N (339 g) was retained from the total injected (1155 g), while the balance of injected nitrate was transported downstream. Storage of NO 3 — N was 117 g or 10% while biotic uptake was 222 g or 19%. Periphyton biomass on slides, chlorophyll a both on slides and on natural cobbles, and net community primary production all indicated a lag in periphyton response to nitrate amendment. Earliest indicators of a biotic response to nutrient amendment were decreases in both tissue C/N and epilithic respiration.

Ecology↗
USGS1986

Determination of the components of stormflow using water chemistry and environmental isotopes, Mattole River basin, California

The chemical and isotopic composition of rainfall and stream water was monitored during a storm in the Mattole River basin of northwestern California. About 250 mm of rain fell during 6 days (∼80% within a 42 h period) in late January, 1972, following 24 days of little or no precipitation. River discharge near Petrolia increased from 22 m 3 s −1 to a maximum of 1300 m 3 s −1 while chloride and silica concentrations decreased only from 3.2 to 2.1 and 11.5 to 8.6 mgl −1 , respectively. Meanwhile, the isotopic composition of the river changed from δD = -42%, δ 18 O = -6.8% and 40 tritium units (T.U.) to extreme values at highest flow of δD = -35%, δ 18 O = -5.9% and 25 T.U. in response to volume-weighted rainfall averaging δD = -19.5%, δ 18 O = -3.1% and 18 T.U. Despite much rainfall of a composition quite different from that of the prestorm river water, “buffering” processes in the watershed greatly restricted changes in the chemical and isotopic content of the river during storm runoff. Because of the physical and hydrologic characteristics of the watershed, major contributions of groundwater to stormflow are very unlikely. The large increase in dissolved chemical load observed at maximum river discharge required that extensive interaction with, and presumably penetration of, soils occurred within a few hours time. Such a large increase in chemical load also required subsurface stormflow throughout a high proportion of the watershed. Chemical and isotopic stabilization of stormflow is believed to be due mainly to displacement of prestorm soil water, with some effects on river chemistry due to rapid rain-soil interactions. The isotopic and chemical composition of prestorm soil moisture cannot readily be predicted a priori because of possible variability in rainfall composition, evaporation, and exchange with atmospheric moisture, nor can it be assumed that baseflow has a predictable relation to the chemical or isotopic composition of water displaced from soils during storms. Therefore, it seems inappropriate to draw conclusions as to the relative proportions of groundwater and rainfall in runoff from a particular storm based only on the average compositions of rainfall, stormflow, and prestorm river water, as has been done in most previous isotope hydrograph studies. Given the great variation in hydrology, topography, soil characteristics, rainfall intensity and quantity, etc. from place to place, the relative amount of overland flow, subsurface flow from the unsaturated zone and of groundwater in stormflow can vary greatly in time and space.

California↗
USGS1984

Results of a solute transport experiment at Uvas Creek, September 1972, California

A 3-hour constant-rate injection of chloride, strontium, and sodium was made into Uvas Creek, Santa Clara County, California, to determine solute transport and sorption properties of a small stream. Seven observation stations were selected within a 635-m reach of the stream where water samples were collected before, during and after the injection. Size-sorted stream sediments placed in the stream prior to the injection were sampled to determine sediment sorption properties. Dissolved solute concentration data are presented in both original and normalized forms to illustrate the different transport properties of the three solutes. Sorbed concentrations are tabulated as a function of both time and grain size. Calculations of streamflow and sorptive distribution coefficient are given.

California↗