摘要:

AbstractEnvironmental magnetism can be used for sediment source tracing in situations such as stream junctions where two catchments deliver magnetically distinguishable, well combined average source mixes to a trunk stream. Consistent mineral magnetic parameter relationships show that spatially and temporally constant magnetic mineral assemblages occur along reaches of natural streams. For most of the confluence mixing situations examined it is possible to distinguish between tributaries using magnetic parameter relationships. Using these relationships, relative tributary contributions to the resultant downstream mix can be quantified. The method can be used for tracing suspended and bedload sediments so that the principal source catchments can be determined by a sequence of measurements at stream junctions along a drainage network. There is considerable potential for using this new and easily applied method for studies of sediment delivery processes and sediment movement in fluvial environments.

ISSN:0885-6087    

DOI:10.1002/hyp.3360070402

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAn integrated programme of hydrological monitoring at the 10 km2Allt a' Mharcaidh catchment in north‐east Scotland has been based on observations at plot, hillslope and catchment scale. The resonse of the principal soil types has been characterized from a combination of throughflow and three‐dimensional tensiometer data at plot scale, and plot sequences have been used to investigate hillslope scale effects. Seep emergence is associated with downslope drainage and local topographic convergence; in parallel preferential pathways generate a highly dynamic throughflow response. Catchment and subcatchment hydrographs mirror the twin dynamic observed at hillslope scale, and a unified hypothesis of response is presented which is consistent with all scales of observati

ISSN:0885-6087    

DOI:10.1002/hyp.3360070403

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractGroundwater flows and travel times were analyzed under a landfill site characterized by a thick unsaturated zone, in an arid environment, using two‐dimensional models. Transport in the unsaturated zone is important in arid environments with thick vadose zones and usually determines the travel time of groundwater from the landfill site to the regulatory compliance surface. The combined use of a parallel flow (Dupuit‐Forchheimer) areal model and vertical cross‐sectional model is explored at a site typical in the utility industry. Flow paths and travel times to the compliance zone are obtained for use in landfill site design or environmental impact assessments. Sensitivity analysis shows that boundary conditions are important factors influencing the entire analysis and thus need to be confirmed with field measure

ISSN:0885-6087    

DOI:10.1002/hyp.3360070404

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTime sequences of tracer release from an alpine snowpack were investigated at Mammoth Mountain, California in 1989. Lysimeter discharge and conductivity were recorded at 30 minute intervals. Three separate applications of chemical tracers were added to the snow surface to provide an ionic signal with known origins in the snowpack. Grab samples of meltwater and snow from snow pits were analysed for chemical composition. There were three distinct discharge periods, each characterized by diurnal fluctuations in discharge and conductivity. An inverse relation between discharge and conductivity was interpreted as the combination of a concentrated signal from regions in the pack less subject to leaching and a relatively dilute signal from near the snow surface where the snow was actively melting Conductivity peaks were highest and diurnal changes greatest immediately following periods of freezing. Grab samples showed little correlation with either 30 minute or daily average conductivity. Relative concentrations of individual ions in meltwater were similar between samples. Non‐systematic grab sampling of snowpack meltwater is shown to be potentially misleading because of multiple ionic pulses over the ablation season and strong diurnal fluctuations in chemical concentrations. Continuous measurements of discharge conductivity are a good indicator of diurnal and seasonal changes in the rate of ion release from the snowpack, and should be used to guide sampling. Composite, or time‐integrated samples rather than grab samples may be required to estimate daily and weekly rates of ion release in melting s

ISSN:0885-6087    

DOI:10.1002/hyp.3360070405

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractDuring the summer of 1989 surface sediment samples were collected in Lake Coeur d'Alene, the Coeur d'Alene River and the St Joe River, Idaho, at a density of approximately one sample per square kilometre. Additional samples were collected from the banks of the South Fork of the Coeur d'Alene and the Coeur d'Alene Rivers in 1991. All the samples were collected to determine trace element concentrations, partitioning and distribution patterns, and to relate them to mining, mining related and discharge operations that have occurred in the Coeur d'Alene district since the 1880s, some of which are ongoing.Most of the surface sediments in Lake Coeur d'Alene north of Conkling Point and Carey Bay are substantially enriched in Ag, As, Cu, Cd, Hg, Pb, Sb and Zn relative to unaffected sediments in the southern portion of the lake near the St Joe River. All the trace element enriched sediments are extremely fine grained (mean grain sizes « 63 μm). Most of the enriched trace elements, based on both the chemical analyses of separated heavy and light mineral fractions and a two step sequential extraction procedure, are associated with an operationally defined Fe oxide phase; much smaller percentages are associated either with operationally defined organics/sulphides or refractory phases.The presence, concentration and distribution of the Fe oxides and heavy minerals indicates that a substantial portion of the enriched trace elements are probably coming from the Coeur d'Alene River, which is serving as a point source. Within the lake, this relatively simple point source pattern is complicated by a combination of (1) the formation of trace element rich authigenic Fe oxides that appear to have reprecipitated from material solubilized from anoxic bed sediments and (2) physical remobilization by currents and wind driven waves. The processes that have caused the trace element enrichment in the surface sediments of Lake Coeur d'Alene are likely to continue for the foreseeable futur

ISSN:0885-6087    

DOI:10.1002/hyp.3360070406

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractFor many years hydrologists have tried to build physically realistic models which are still simple enough to be fitted to a range of observations made in the field. This is an ongoing process which will become even more difficult as the quality and variety of field and remotely sensed data improves. Hence models must be able to predict soil moisture patterns in time and in space as well as the outflow hydrograph. The model presented here (TOPMODEL) aims to predict the nature of variable source areas in a way that reflects their dynamics over space and time. All component processes are described and shown in operation. As TOPMODEL and similar models have a growing popularity, this paper can be seen as a demonstration of the model's predictive capabilities. The model is applied to the catchments of Plynlimon, mid‐Wales for 1984, 1985 and 1986 data sets. The model has been thoroughly tested and cross‐validated against independent data sets for different time periods, for a separate catchment, for internal gauges and for wet and dry periods. The resulting predicted soil moisture patterns show a small, semi‐permanent variable source area that has the ability during large storms to expand dynamically over short time periods. Spatial predictions of evapotranspiration are also shown which reflect the influence of soil moisture patterns on this process. The weakest component of the model is the representation of root zone evaporation and how this pre‐sets the antecedent condition of the catchment during long dry

ISSN:0885-6087    

DOI:10.1002/hyp.3360070407

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBasin lag time varies not only between basins but also within a basin. To explain this variation, the basin lag time was hypothesized as a function of the ratio of the channel length from the centroid to the outlet of the basin, divided by the velocity of flow at the gauging site at the time of passage of peak discharge. The records of six basins were used to test this hypothesis. The results are not incompatible with this hypothesis.

ISSN:0885-6087    

DOI:10.1002/hyp.3360070408

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360070401

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY