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B. H. Vaughn

Publications and source records attributed to B. H. Vaughn.

6 recordsLinked to original sources
USGS2012

Columbia Glacier, Alaska: Changes in velocity 1977-1986

The Columbia Glacier, a grounded, iceberg-calving tidewater glacier near Valdez, Alaska, began to retreat about 1977. Drastic retreat occurred in 1984, and by early 1986, retreat amounted to 2 km. The glacier has thinned more than 100 m since 1974 at a point 4 km behind the 1974 terminus position. Between 1977 and 1985 the lower glacier ice velocity increased from 3–8 m/d to 10–15 m/d. Ice velocity in the region 0.5 km above the terminus was highest near the time the glacier was most receded (late fall), and lowest near the time of maximum length (early summer), for years 1977–1982. Velocity in the region 52–57 from the head of the glacier was highest in mid-spring, and lowest in early fall from 1977 to 1985. Through the years 1983–1985, the dates of maximum and minimum velocities within 0.5 km of the receding terminus tended toward the dates of the 52–57 km maximum and minimums. This occurred because as the terminus receded, it was no longer strongly influenced by the reverse slope of the terminal moraine shoal. Velocities near the terminus fluctuated by 2–3 m/d during summer and fall, when liquid water input was variable, and were relatively constant during winter. Hourly variations in ice velocities are controlled by liquid water input to the glacier hydraulic system and tide stage. Velocity increases near periods of high surface water input and decreases during periods of high tide as a result of hydrostatic back pressure.

Journal of Geophysical Research Solid Earth↗
USGS2003

Determining long time-scale hyporheic zone flow paths in Antarctic streams

In the McMurdo Dry Valleys of Antarctica, glaciers are the source of meltwater during the austral summer, and the streams and adjacent hyporheic zones constitute the entire physical watershed; there are no hillslope processes in these systems. Hyporheic zones can extend several metres from each side of the stream, and are up to 70 cm deep, corresponding to a lateral cross‐section as large as 12 m 2 , and water resides in the subsurface year around. In this study, we differentiate between the near‐stream hyporheic zone, which can be characterized with stream tracer experiments, and the extended hyporheic zone, which has a longer time‐scale of exchange. We sampled stream water from Green Creek and from the adjacent saturated alluvium for stable isotopes of D and 18 O to assess the significance and extent of stream‐water exchange between the streams and extended hyporheic zones over long time‐scales (days to weeks). Our results show that water residing in the extended hyporheic zone is much more isotopically enriched (up to 11‰ D and 2·2‰ 18 O) than stream water. This result suggests a long residence time within the extended hyporheic zone, during which fractionation has occurred owing to summer evaporation and winter sublimation of hyporheic water. We found less enriched water in the extended hyporheic zone later in the flow season, suggesting that stream water may be exchanged into and out of this zone, on the time‐scale of weeks to months. The transient storage model OTIS was used to characterize the exchange of stream water with the extended hyporheic zone. Model results yield exchange rates (α) generally an order magnitude lower (10 −5 s −1 ) than those determined using stream‐tracer techniques on the same stream. In light of previous studies in these streams, these results suggest that the hyporheic zones in Antarctic streams have near‐stream zones of rapid stream‐water exchange, where ‘fast’ biogeochemical reactions may influence water chemistry, and extended hyporheic zones, in which slower biogeochemical reaction rates may affect stream‐water chemistry at longer time‐scales.

Hydrological Processes↗
USGS1995

Changing drainage patterns within South Cascade Glacier, Washington, USA, 1964-1992

The theoretical patterns of water drainage are presented for South Cascade Glacier for four different years between 1964 and 1992, during which the glacier was thinning and receding. The theoretical pattern compares well, in a broad sense, with the flow pattern determined from tracer injections in 1986 and 1987. Differences between the patterns may result from the routing of surface meltwater in crevasses prior to entering the body of the glacier. The changing drainage pattern was caused by glacier thinning. The migration of a drainage divide eventually rerouted most of the surface meltwater from the main stream that drained the glacier in 1987 to another, formerly smaller, stream by 1992. On the basis of projected glacier thinning between 1992 and 1999, we predict that the drainage divide will continue to migrate across the glacier.

Biogeochemistry of seasonally snow-covered catchme↗
USGS1985

Short-term velocity measurements at Columbia Glacier, Alaska: August-September 1984

Ice velocity data are presented for the lower reach of Columbia Glacier, Alaska. The data span a 29 day period and contain 1,072 angle sightings from two survey stations to 22 markers placed on the ice surface, and 1,621 laser measurements of the distance to one of those markers (number 11) from another station. These short-interval observations were made to investigate the dynamics of the glacier and to provide input to models for estimation of future retreat and iceberg discharge. The mean ice velocity (at marker number 11) was approximately 9 m/day and ranged from 8 to < 15 m/day. The data set includes a well defined 2-day, 50% velocity increase and a clear pattern of velocity fluctuations of about 5% with approximately diurnal and semiurnal periods. (Author 's abstract)

Alaska↗