摘要:

AbstractThere are six classes of water and five geologic environments in the subarctic Nahanni karst. During the summers of 1972 and 1973, 214 water samples were collected from 15 of the 30 hydrogeologic categories. Linear discriminant function analysis, using five measured and two derived chemical variables, indicates that there are statistically significant (0.005 level) differences in water chemistry between similar waters in different geologic environments, between waters in the same geologic environment, and between waters in different hydrogeological categories. Geological environment labels a natural water because it determines the availability of soil CO2and of soluble minerals. Measurements indicate that mean soil log PCO2is greatest in areas of shale mantled by till (−2.39), and least in areas of sandy fluvioglacial drift (−3.27). Low values on the sandy drift are due to the sparse shrub vegetation, and to the high degree of soil aeration; soils in areas of shale are clay‐rich and support a dense boreal forest. Hydrology influences water chemistry because it determines how much CO2natural waters pick up from the environment and how much they subsequently lose to the atmosphere, and as a result, whether they dissolve or deposit soluble materials. The similarity between mean calculated log PCO2in natural waters (−2.92) and mean measured soil log PCO2(−2.80) suggests that natural waters in Nahanni are dose to equilibrium with mean soil

ISSN:0197-9337    

DOI:10.1002/esp.3290070103

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractSome sand‐bed streams exhibit unsteady supercritical flow in the form of periodic bores that propagate downstream. The bores are formed by unstable antidunes, which store water while growing in amplitude and then release the stored water, when the antidunes wash out to form a plane bed. A cyclic process of antidune growth, oversteepening, antidune breaking, then bed‐form washout produced bores on regular periodic intervals of roughly 15 s in Medano Creek, Great Sand Dunes National Monument, Colorado. This periodic bore‐generating pulsating flow, is bed‐form dependent, and it requires sufficiently high flow velocities and sediment transport rates to form unstable breaking antidunes. The Froude number maximum is 1.8, below that required for slug flow.Pulsating flow has been observed in flumes, arroyos, and rivers, and it may be more common than initially anticipated. Its high erosive capacity can influence both channel morphology and the character of associated sedimentary d

ISSN:0197-9337    

DOI:10.1002/esp.3290070104

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractThe valleys of Epirus, in NW Greece, are floored by alluvium laid down in historical times. In an attempt to evaluate the relative importance of diagenesis and of parent material in determining its local character, the alluvium was compared with the principal source deposits, namely the red beds of the late Quaternary Kokkinopilos Formation and the brown Mediterranean soils that have developed on flysch outcrops. Rehydration of the haematite pigment after deposition coupled with silt‐clay depletion during redeposition of the red beds is responsible for the drab colour of the valley‐floor deposits in limestone catchments. Where the alluvium was derived from brown soils, little mineralogical change has occurred. Some reduction and mobilization of iron has affected Kokkinopilos beds still in place, possibly during periods of seasonal waterlogging under oak forest, to produce a veining pattern akin to that found in pseudo‐gley

ISSN:0197-9337    

DOI:10.1002/esp.3290070105

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractVolcanic activity on sub‐Antarctic Marion Island is found to have occurred only during the interglacials. The present volcano distribution is associated with a radial and peripheral fault system, the location of which appears to be related to the former glacier distribution. An hypothesis is presented suggesting that the faulting is a result of deglaciation and that the specific location of the faults is due to the differential stresses occurring between ice‐covered and ice‐free areas during isostatic uplift. The faulting initiates volcanism due to the location of the island within a volcanic r

ISSN:0197-9337    

DOI:10.1002/esp.3290070106

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIn order to study the relationship between water composition and stream flow rate, it is desirable to sample at a frequency related to flow rate, especially during storm events. In a rural catchment of 18 ha near Oxford, the rate of rainfall was found to be linearly related to discharge on the rising limb of the stream hydrograph. A sampling system was therefore designed in which electrical pulses from a tipping‐bucket raingauge were used to initiate and control the action of an automatic water sampler. A threshold rainfall intensity is set above which sampling commences. Sampling then continues at regular increments of rainfall until the intensity drops below the threshold, after which sampling occurs at regular intervals during the period that the stream flow reverts to normal.The CMOS electrical circuits which control the sampling also operate a cassette tape recorder which records the time of each tip of the raingauge and operation of the sampler. Since the sytem is designed to impose very little additional load on the battery which powers the water sampler, and can operate unattended for at least a fortnight, it is ideal for use in small, remote catchments. The system has been extended to include measurements of water temperature and could provide other measurements as wel

ISSN:0197-9337    

DOI:10.1002/esp.3290070107

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDuring a 3‐year period, several aspects of the glacier‐rock interface were studied in a cavity beneath 5–8 m of ice near the terminus of Grinnell Glacier, Montana, U.S.A. Continuous week‐long records of the summer sliding rate revealed a very uniform speed of about 12 m a−1during the summer, a value about 20 per cent higher than the average annual sliding rate. Several decimetre‐sized rock fragments were broken from the glacier bed near the lee sides of bedrock ledges and transported down‐glacier. In the course of a two‐week long experiment, the glacier abraded its bed significantly and non‐uniformly. It is of interest that significant quarrying and abrasion occurred under thin ice with relatively little

ISSN:0197-9337    

DOI:10.1002/esp.3290070108

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractIf the three‐dimensional form of a hillslope is regarded as an infinite population of two‐dimensional slope profiles, values for attributes of the form of the hillslope can be determined by sampling and estimating the means of the attributes of the population of slope profiles. Twelve attributes are examined in seven first‐order drainage basins located on the South Downs in East Sussex to determine necessary sample sizes. Results show that if spatial randomness is assumed the size of sample required varies considerably from one attribute to another but is commonly very large. Of four alternatives to spatial randomness that are tested, consideration of both hillslope plan form and valley asymmetry are shown not to lead to reduction in sample size. However, results do suggest that maximum slope, percentage of profile length in the range 5° to<10°, and mean angular difference between adjacent slope segments may all be dependent upon distance of the slope profile down valley. Furthermore, initial tests of the effect of spatial autocorrelation suggest that for some attributes consideration needs to be given to this factor when determining sampling str

ISSN:0197-9337    

DOI:10.1002/esp.3290070109

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractDirect measurement of slope retreat on three unvegetated slope profiles on unmodified, pre‐1939, strip‐mine dumps revealed average ground losses ranging from 29 to 33 mm/year. Measured ground losses are twice those estimated from the Universal Soil Loss Equation. Slope length seems less significant than frost action in influencing erosion on these slo

ISSN:0197-9337    

DOI:10.1002/esp.3290070110

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractForestry is generally considered to be a land use giving low sediment yields. However, in Britain most forestry is on land that requires extensive drainage, and it was found that the drainage of a small upland catchment resulted in sediment yields over the following five years equivalent to nearly half a century's load at pre‐drainage rates. Subsequent sediment yields did not decline to pre‐drainage levels, but remained about four times higher, as a result of erosion of the dra

ISSN:0197-9337    

DOI:10.1002/esp.3290070111

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY

摘要:

AbstractExamination of spatial variability of streamflow in headwater areas can provide important insight about factors that influence hillslope hydrology. Detailed observations of variations in stream channel input, based on a tracer experiment, indicate that topography alone cannot explain flow variability. However, determination of changes in channel input on a small spatial scale can provide valuable clues to factors, such as structural geology that control subsurface flows.

ISSN:0197-9337    

DOI:10.1002/esp.3290070112

出版商:John Wiley&Sons, Ltd    

年代:1982

数据来源: WILEY