bluuebunny/crossref_metadata_2025_split huggingface dataset:
One year irrigation experiment to assess losses and runoff volume relationships for a residential road in hertfordshire, England
Authors: Hollis G. E. , Ovenden J. C. 
Published: February 2007

AbstractSix sections of a residential road (75 mm bituminous macadam over 200mm lean mix concrete over 100 mm hoggin with a recent surface dressing of 10 mm granite chippings and K1‐70 binder) that drain to individual instrumented gully pots were irrigated along the kerb and then over the whole road approximately monthly for a year. The aim was the determination of terminal infiltration losses, initial losses, percentage runoff, and infiltration curves for the kerb and road surface. The results were not as expected from the literature.There is an annual cycle of infiltration losses at the kerb with a winter peak caused by frost action that is 3.2 times greater than the terminal loss rate at kerbs in summer. The terminal loss rate for an ‘average catchment’ was 6.4251 min−1 from the road surface and 14.251 min−1 in summer and 46.281 min−1 in winter at the kerb. Evaporation was usually more than an order of magnitude less significant than infiltration.The wide variation in initial losses before runoff commenced was inexplicable. Two sections of road behaved in the classic manner with initial losses averaging 0.8 mm, two other catchments had highly variable initial losses in the range 1.2 to 8.8mm, and the last two pieces of road were even more erratic.The percentage runoff for those irrigations of over 15 mm of equivalent rainfall was never more than 10 per cent. The maximum per cent runoff was around 50 per cent following 10 mm of equivalent rainfall for kerbside irrigation and only 5 mm of irrigation over the whole road. There were no significant simple or multiple regression relationships between percentage runoff from the kerb or the whole road irrigations and irrigation amount, slope, UCWI, and SMD.Infiltration curves, for kerb and road irrigation, were so diverse that they do not represent the ‘simple impervious surfaces’ envisaged at the start of the experiment and described in the literature. Since the artificial irrigation of kerbs and roads has failed to substantiate existing theory, these experiments should be repeated at a variety of sites with a high rate of irrigation.
Chloride in precipitation and streamwater for the upland catchment of river severn, mid‐wales; some consequences for hydrochemical models
Authors: Neal Colin , Christophersen Nils , Neale Richard , Smith Christopher J. , Whitehead Paul G. , Reynolds Brian 
Published: February 2007

AbstractVariations in the concentration of Cl in rainfall and stream runoff are presented for two catchments in the Hafren forest of mid‐Wales, Great Britain. Despite the large fluctuations in rainfall concentrations, Cl in the streamwater remains relatively constant. Using the two‐reservoir Birkenes model, an attempt was made to simulate observed Cl in streamwater. The original model was unable to reproduce the observations and several modifications are suggested to provide better simulations. The resulting model is not the only one capable of reproducing the observations; other hydrochemical models will most probably also achieve this although emphasis will in each case be placed on different aspects. In this paper, it is suggested that the stochastic properties of water movement and chemical processes can account for the streamwater chemistry responses observed. On the catchment scale these processes will lead to an apparently deterministic behaviour that may well be described by simple relationships.
On numerical errors associated with the iterative alternating direction implicit (Iadi) finite difference solution of the two dimensional transient saturated‐unsaturated flow (Richards) equation
Authors: Parissopoulos G. A. , Wheater H. S. 
Published: February 2007

AbstractNumerical models for simulation of multidimensional unsaturated flow are becoming increasingly available, but relatively little has been reported on the detailed analysis of numerical errors associated with such schemes. For unsaturated‐saturated flow, further complexity is introduced to the highly non‐linear unsaturated problem as the form of governing equation changes within the flow field. In this paper, two‐dimensional simulation of infiltration to a water table is considered. Numerical errors associated with selection of time step, grid geometry, convergence criteria, and the representation of internodal hydraulic conductivity are discussed with respect to moisture content profiles and mass balance error. Although solution sensitivity to numerical parameters is problem specific, the results presented indicate the nature and magnitude of numerical effects which should not be overlooked in model applications.
Interactions between groundwater seepage and sediment porewater sulphate concentration profiles in lake anna, Virginia
Authors: McIntire Pamela E. , Mills Aaron L. , Hornberger George M. 
Published: February 2007

AbstractMost sulphur diagenesis models predict that SO42‐ concentrations decrease exponentially with increasing sediment depth and are lower than that of the overlying water throughout the sediments. Low SO42‐ concentrations (less than 0.2 mM) are common in the sediments of Lake Anna that receive acid mine drainage; however, sediment with as much as 20 mM SO42‐ at about 20cm below the sediment surface is also seen in this section of the lake. A decision tree was proposed to investigate the cause of the high SO42‐ concentrations at depth (HSD) in the sediment. The first possibility proposed was that an increase in the quantity of groundwater flowing through Lake Anna sediments may increase groundwater advection of SO42‐ or oxygen which would induce sulphide oxidation. This hypothesis was tested by measuring groundwater flow. HSD profiles were found in a discrete region of the lake; however, stations having these profiles did not have higher groundwater flow than other sites sampled. Alternate explanations for the HSD profiles were that the region in which they occurred had: (1) unusual sediment chemical compositions; (2) a different source of regional groundwater, or (3) a lateral intrusion of high SO42‐ groundwater. There were no differences in sulphide and organic matter concentrations between the two regions. The area which has HSD in the sediment covers a large area in the middle of the lake, so it is unlikely that it has a unique source of regional groundwater. The third alternative was supported by the fact that in all three sample years, HSD stations were located in the preimpoundment stream channel, which is a likely lateral flow path for groundwater containing high SO42‐ concentrations.
Modelling rainfall/watertable relations using linear response functions
Authors: Armstrong Adrian C. 
Published: February 2007

AbstractLinear system theory can be used to model and predict watertable responses to precipitation inputs in an artificially drained field. The response function is mathematically equivalent to the Unit Hydrograph concept familiar to hydrologists. This paper shows that it is possible to derive such response functions, and comments on the problems encountered in their derivation. Response functions for two contrasted sites are presented, and the possibilities for their use discussed.
A comparison of instrumental dewatering methods for the separation and concentration of suspended sediment for subsequent trace element analysis
Authors: Horowitz A. J. , Elrick K. A. , Hooper R. C. 
Published: February 2007

AbstractA comparison involving both field and laboratory trials was performed to evaluate the utility of two continuous‐flow centrifuges and a tangential‐flow filtration system for dewatering suspended sediments for subsequent trace element analysis. Although recovery efficiencies for the various devices differ, the analytical results from the separated suspended sediments indicate that any of the tested units can be used effectively and precisely for dewatering. Further, the three devices appear to concentrate and dewater suspended sediments in such a manner as to be equivalent to that which could be obtained by in‐line filtration. Only the tangential‐flow filtration system appears capable of providing both a dewatered sediment sample and a potentially usable effluent, which can be analysed for dissolved trace elements.The continuous‐flow centrifuges can process whole water at an influent feed rate of 41 per minute; however, when suspended sediment concentrations are low (<30mg−1), when small volumes of whole water are to be processed (30 to 401), or when suspended sediment mean grain size is very fine (<10 μm), influent feed rates of 21 per minute may be more efficient. Tangential‐flow filtration can be used to process samples at the rate of 11 per minute.
A laboratory test of the soil chemical submodels of two models of catchment acidification
Authors: Grieve Ian C. 
Published: February 2007

AbstractParameters for ion exchange selectivity and aluminium hydroxide dissolution in the soil chemical submodels used in applications of the Birkenes model and of MAGIC are compared and several discrepancies identified for organic soils. A laboratory column simulation of the soil chemical submodels is proposed and applied to soils from the Loch Dee area in Galloway. Experimental results were well predicted by a simplified version of MAGIC, with ion exchange selectivity parameters similar to those used in a previous simulation of one subcatchment of Loch Dee. The aluminium hydroxide dissolution parameter used previously was found to be too low for the organic soil materials, where a value of 106 predicted the experimental results more closely. The model developed also included a simple silicate weathering reaction to release base cations into the system. It is concluded that such simple laboratory simulations are useful for independent calibration of the soil chemical submodel of catchment models.
Trials of an acoustic method of measuring piezometric levels in standpipes
Authors: Heath W. , S. Dedi 
Published: February 2007

AbstractThe role of the open standpipe Casagrande piezometer for determining soil pore pressures is still important because of its simplicity and reliability in comparison with transducer type instruments. Such factors are especially relevant when instrumentation is used on remote and inaccessible sites. The limitations of Casagrande type systems relate to poor response times, particularly in soils of low permeability, and the complexity of the normal gas bubbling equipment used to monitor and record data from this type of piezometer.The response can be improved, providing the design of the installation is taken into consideration in terms of the piezometer collection area and standpipe sizes. A simple acoustic technique has been developed by Geotechnical Monitoring Ltd, to monitor and record piezometric levels. This is based on measuring the period for the return echo of a high frequency signal; a technique widely used to focus cameras that has been found to be reliable and accurate. However, trials on landslide sites in Indonesia highlighted problems which related more to a lack of development rather than any fundamental problems in the method of monitoring standpipes. This paper describes such problems and how they might be overcome.
Analysis of solute transport with a hyperbolic scale‐dependent dispersion model
Authors: Mishra S. , Parker J. C. 
Published: February 2007

AbstractAn empirical hyperbolic scale‐dependent dispersion model, which predicts a linear growth of dispersivity close to the origin and the attainment of an asymptotic dispersivity at large distances, is presented for deterministic modelling of field‐scale solute transport and the analysis of solute transport experiments. A simple relationship is derived between local dispersivity, which is used in numerical simulations of solute transport, and effective dispersivity, which is estimated from the analysis of tracer breakthrough curves. The scale‐dependent dispersion model is used to interpret a field tracer experiment by nonlinear least‐squares inversion of a numerical solution for unsaturated transport. Simultaneous inversion of concentration‐time data from several sampling locations indicates a linear growth of the dispersion process over the scale of the experiment. These findings are consistent with the results of an earlier analysis based on the use of a constant dispersion coefficient model at each of the sampling depths.
Mathematical modelling of sea water intrusion, Nauru Island
Authors: Ghassemi F. , Jakeman A. J. , Jacobson G. 
Published: February 2007

AbstractA two‐dimensional finite element model for density dependent groundwater flow was calibrated to simulate sea water intrusion in Nauru Island in the Central Pacific Ocean. Nauru Island occupies an area of 22 km2 and supports a population of 8500. The island has been mined for its phosphate deposits and current reserves indicate that the mine has about eight years life remaining. The water supply of the island is about one third dependent on imported water which is also used as ballast on the phosphate ships. Imported water will not be available in the future, and a hydrogeological investigation shows that the island is underlain by a fresh water layer, less than 5 m thick. The freshwater layer overlies a thick transition zone of brackish water which in turn overlies sea water. Simulation of several management options shows that it is possible to substitute current importation of fresh water by careful extraction from the groundwater resources of the island.
Role of hypsometry and planform in basin hydrologic response
Authors: Howard Alan D. 
Published: February 2007

AbstractThe effects of variations of drainage basin morphometry and relief characteristics on flood peak magnitude and time‐to‐peak are investigated using simulated stream networks. The networks are produced by three models: headward growth, systematic capture, and minimum power relaxation. Translational and kinematic wave flood routing were used to generate synthetic hydrographs. Peak discharge and time‐to‐peak are predictable to a high degree by five different sets of morphometric‐relief parameters. In order of decreasing order of importance in predictive ability the parameters characterize basin size, relative relief, basin concavity, and basin shape. Both simulated and natural stream networks exhibit strong dependence of planimetric morphometry upon basin concavity. The effect of this dependency is to increase the effect of basin concavity upon flood hydrographs.
Applications of hydrologic information automatically extracted from digital elevation models
Authors: Jenson Susan K. 
Published: February 2007

AbstractDigital elevation models (DEMs) can be used to derive a wealth of information about the morphology of a land surface. Traditional raster analysis methods can be used to derive slope, aspect, and shaded relief information; recently‐developed computer programs can be used to delineate depressions, overland flow paths, and watershed boundaries. These methods were used to delineate watershed boundaries for a geochemical stream sediment survey, to compare the results of extracting slope and flow paths from DEMs of varying resolutions, and to examine the geomorphology of a Martian DEM.
Geographic information systems and non‐point source water quality and quantity modelling
Authors: Vieux B. E. 
Published: February 2007

AbstractHydrologic processes are affected by the spatial variability of soils, topography, land use and cover, climate, and human‐induced changes and management. Because contaminants are transported by runoff to surface waters and by infiltration and deep percolation to groundwater, hydrologic processes are often at the core of water quality and quantity concerns. Water quality and quantity affected by non‐point sources of contaiminants is dependent on spatially distributed attributes of a catchment or watershed.The integration or linkage of the spatial data handling capabilities of a GIS with a distributed process, hydrologic model offers the advantages associated with utilizing the full information content of the spatially distributed data to analyse the hydrologic processes. Distributed process models use computational elements smaller than the scale of the process or the system being modelled. The information content of the model output is greater than a lumped model though obtained at greater cost. A GIS is capable of manipulating both the input and output parameters required by distributed process models.This paper presents a review of water quality and quantity modelling and GIS applications in water resources. An application of the GIS, ARC/INFO and the finite element solution to the kinematic wave equations is presented. In this application, ARC/INFO is used to process the spatially variable terrain in a small watershed using a Triangular Irregular Network on TIN. The TIN facets are used to provide land surface slope in a finite element solution of overland flow which is a fundamental subprocess affecting non‐point source, water quality and quantity.
An evaluation of an automated hollow‐fibre ultrafiltration apparatus for the isolation of colloidal materials in natural waters
Authors: Marley N. A. , Gaffney J. S. , Orlandini K. A. , Dugue C. P. 
Published: February 2007

AbstractColloidal materials and macromolecules that are less than 0.45 mircons in diameter can act to transport both hydrophobic and hydrophilic contaminations in subsurface waters. An automated hollow‐fibre ultrafiltration apparatus is described and evaluated regarding its ability to physically size and isolate colloidal materials from natural waters. Sufficient size‐fractionated colloidal samples can be obtained from 60 litre samples to perform inorganic, organic, and radionuclide characterizations, as well as allow the binding capacities of humic and fulvic materials to be evaluated. Samples processed in the field with the automated system were compared with laboratory analyses using single cartridge hollow‐fibre ultrafilters and found to agree well with each other. Typical sample reproducibilities were with 15 per cent. The results indicate that field collection of colloidal materials is feasible with minimal sample perturbation using the automated sampler.
Infiltration measurements—a review
Authors: Youngs E. G. 
Published: February 2007

AbstractInfiltration theory developed from Richards' equation for the movement of water in unsaturated soil is outlined and used as a basis for considering measurements made with ring infiltrometers, rainfall simulators and tension infiltrometers. In particular, the three‐dimensional soil‐water flow occurring with many of these measurement techniques is considered. Complicating factors of soil heterogeneity, soil swelling and shrinking, and soil aggregation, that limit the interpretation of field measurements using classical theory, are discussed.
Soil pipe contribution to steady subsurface stormflow
Authors: Nieber John L. , Warner Glenn S. 
Published: February 2007

AbstractFlow through a saturated idealized hillslope with a single soil pipe was simulated using a finite difference solution to the equation for three‐dimensional Darcian flow in saturated heterogeneous media. The proportions of hillslope discharge originating from flow through the soil matrix and from flow through a soil pipe were determined, considering such factors as the radius, depth and length of the pipe, pipe spacing, and the length and slope of the hillslope. Results demonstrate that soil pipes can contribute a significant amount, and in many instances, the majority of total subsurface stormflow.
Dynamics of seasonal recharge beneath a semiarid vegetation on the gnangara mound, Western Australia
Authors: Sharma M. L. , Bari M. , Byrne J. 
Published: February 2007

AbstractTo estimate seasonal changes in recharge to the underlying sandy aquifer, the soil water dynamics of the unsaturated zone was monitored down to a depth of 20 m over a period of three years (1985 to 1987). The measurements were made by a neutron probe at eight locations beneath a native vegetation in a semiarid region, Western Australia, receiving precipitation of 775 mm yr−1. A relatively simple method, based on the analyses of sequentially measured soil water profiles involving utilization of zero flux plane in the unsaturated zone, is presented and used to compute seasonal recharge rates.Drainage fluxes (recharge rates) below two specified depths were estimated. These were: R1 (water flux at a depth of 10 m, just below the maximum rooting depth) and R2 (water flux at a depth of 18 m, just above the water table). These two estimates were significantly different both on a seasonal and annual basis, but their cumulative values for the three year period were very similar. While the annual precipitation varied from 525 to 850 mm yr−1, the corresponding spatially averaged R1 varied from 34 to 149 mm yr−1, and R2 varied from 65 to 80 mm yr−1. A significant difference in recharge between the upslope and downslope positions on a hillslope was ascribed to differences in vegetation density of the understorey and differences in hydraulic properties of subsoils.For the three year period, the average R1 and R2 were 13 per cent and 10 per cent of the precipitation respectively. These values compare favourably with a long‐term estimate based on an environmental tracer technique.
Transmission losses to alluvium and associated moisture dynamics in a semiarid ephemeral channel system in Southern Africa
Authors: Hughes D. A. , Sami K. 
Published: February 2007

AbstractTransmission losses through the bed of ephemeral rivers in arid and semiarid regions can account for a large proportion of the total amount of runoff generated upstream. Losses have typically been estimated by measuring discharge at two points in the channel system. This paper presents some results from a semiarid catchment in South Africa based on moisture observations of the alluvial material using neutron probe access tubes. Channel flow in this catchment is a very infrequent occurrence and consequently presents few opportunities to observe the processes of transmission loss. Only two events have occurred since the beginning of observations in this area (3 October, and 14 November, 1989). the available information is far from complete but suggests that some 75 per cent of the upstream flow in the first event and 22 per cent in the second event was lost to the alluvial material.