bluuebunny/crossref_metadata_2025_split huggingface dataset:
Continuous measurement of the depth of water table (inundation) in wetlands with fluctuating surfaces
Authors: Roulet Nigel , Hardill Steven , Comer Neil 
Published: February 2007

AbstractAssessment of the water table in compressible and/or floating peatland mats requires a remote sensor that can measure simultaneously the elevation of the peat surface and the water level. A simple device, comprising two potentiometers, a float and ‘bog shoe’ was used to measure the water level and peat surface witin 0‐3 mm. The water table (depth of water level relative to the peat surface) was then calculated.
Subsurface flow responses of a small forested catchment in the Ouachita mountains
Authors: Turton Donald J. , Haan Charles T. , Miller Edwin L. 
Published: February 2007

AbstractDespite considerable research performed on forested catchments in the Ouachita Mountains of Oklahoma and Arkansas, little information on hydrological processes in operation is available. Based on catchment physical characteristics, subsurface flow was thought to be an important hydrological process in the region. Therefore, this study was undertaken to determine the occurrence, rates, timing and volumes of subsurface flow, and to estimate the importance of subsurface flow as a streamflow generating process. Subsurface flow was collected from three hillslope sites on a 7.7 ha forested catchment. Hillslope sites drained through natural seepage faces located near stream channels. Subsurface flow was collected from three depths at each hillslope site, below the litter layer, below the a horizon, and within the B horizon (Bt21). Subsurface flow occurred and was measured during 11 of 31 rainfall events. Subsurface flow responded rapidly to the initiation of and to changes in intensity of rainfall at all depths. the rapid response was indicative of flow through soil macropores. B horizon subsurface flow commenced within 10 to 180 min of the initiation of rainfall. Multiple linear regression showed that the volume of subsurface flow generated during a given storm was directly related to rainfall depth and a 7‐day antecedent precipitation index used to represent antecedent water content. About 67 per cent of the total subsurface flow collected during the study was produced in one large storm under wet antecedent conditions. the storm was equal to the 2‐year, 24‐hour storm for the region. Measured subsurface flow volumes were extended to the watershed scale to provide estimates of catchment‐wide contributions to streamflow. It was estimated that subsurface flow contributed from 1 to 48 per cent of total quickflow measured at the catchment outlet. Based on the timing of subsurface flow, it was estimated that subsurface flow May, contribute up to 70 per cent of quickflow before and soon after peak flow.
A laboratory investigation of the leaching of solute from snowpack by rainfall
Authors: Tranter M. , Tsiouris S. , Davies T. D. , Jones H. G. 
Published: February 2007

AbstractUnder controlled laboratory conditions, artificial rain leaches solute from snow columns, and gives rise to leachate with a composition similar to snowmelt, in addition to the solute initially present in the artificial rain. the initial concentration of ions in the leachate, normalized to the concentration of ions found in the original snow and corrected for the solute present in the artificial rain, is similar to those reported in other laboratory and field studies of snowmelt composition, but there is some evidence that the concentration of leached ions declines more rapidly than during snowmelt. Similarly, as in snowmelt studies, not all ions are leached with the same efficiency. Bearing in mind the confounding influences of snow crystal morphology and snow column hydrology, it seems likely that rain will leach solute from snowpack during rain‐on‐snow events, in a manner similar to leaching by snowmelt, and that the precise composition of the leachate will depend on the hydrological routing of rain‐meltwater mixtures through the snowpack.
Future of distributed modelling
Authors: Jensen Karsten Høgh , Mantoglou Aristotelis 
Published: February 2007

AbstractThe state of the art of modelling hydrological systems using distributed modelling techniques is discussed and the theoretical problems caused by the heterogeneities always present in field soil systems are emphasized. It is argued that such heterogeneities need to be considered to develop physically based large‐scale models applicable at the scale of the numerical discretization blocks. Stochastic approaches seem to provide a rational framework for treating the difficult to characterize spatial variability and for establishing a link between parameter uncertainty and prediction uncertainty. It is emphasized that more research in theory development and testing is required before complete large‐scale models are obtained and this had to be carried out jointly with field tests. More research is also required in field measurement techniques to accurately supply the deterministic and statistical parameters required in distributed models.
Future of distributed modelling: The Systeme Hydrologique Europeen
Authors: Bathurst J. C. , O'Connell P. E. 
Published: February 2007

AbstractCurrent and projected UK activities with the Système Hydrologique Européen (SHE) hydrological modelling system are examined. Development of the SHE arose from the need for a new modelling approach for use in assessing the environmental impacts of river basin development and the system is particularly suited to predicting the impacts of land use and climatic changes and to applications to basins with sparse data sets. the basic hydrology model is now being developed into a powerful contaminant and sediment transport modelling system called SHETRAN‐UK and components are also being proposed to account for landslide and gully erosion. Applications of the SHE have been made at spatial scales ranging from 30 m2 to 5000 km2 and in a variety of environments. These have demonstrated an ability to achieve calibration on the basis of short time series records and field evaluation of parameters, to provide multiple outputs on a spatially and temporally distributed basis, and to explore basin response mechanisms. They have also indicated the importance of integrating field measurements within the calibration process. the effect of the scale of model grids on parameter evaluation and on simulation results still needs to be investigated and there is a need for field process studies in areas where there is a poor understanding, to improve certain of the process representations within the SHE. However, new ideas are being explored to account for subgrid spatial variability in parameter values and to develop a validation methodology for testing the predictive capability of the SHE. Future developments will include the use of geographical information systems and data processing packages to aid data handling, expert systems to improve the efficiency of calibration, and parallel processing and other new computational techniques. an expanding range of applications will see physically based hydrological modelling systems at the core of decision support systems and integrated at the continental scale with general circulation modelling systems.
The future of distributed models: Model calibration and uncertainty prediction
Authors: Beven Keith , Binley Andrew 
Published: February 2007

AbstractThis paper describes a methodology for calibration and uncertainty estimation of distributed models based on generalized likelihood measures. the GLUE procedure works with multiple sets of parameter values and allows that, within the limitations of a given model structure and errors in boundary conditions and field observations, different sets of values May, be equally likely as simulators of a catchment. Procedures for incorporating different types of observations into the calibration; Bayesian updating of likelihood values and evaluating the value of additional observations to the calibration process are described. the procedure is computationally intensive but has been implemented on a local parallel processing computer. the methodology is illustrated by an application of the Institute of Hydrology Distributed Model to data from the Gwy experimental catchment at Plynlimon, mid‐Wales.
Stochastic modelling of groundwater flow and solute transport in aquifers
Authors: Jim Yeh T.‐C. 
Published: February 2007

AbstractThis paper presents an introductory overview of recently developed stochastic theories for tackling spatial variability problems in predicting groundwater flow and solute transport. Advantages and limitations of the theories are discussed. Lastly, strategies based on the stochastic approaches to predict solute transport in aquifers are recommended.
Deposition and resuspension of fine particles in a riverine ‘dead zone’
Authors: Tipping E. , Woof C. , Clarke K. 
Published: February 2007

AbstractParticulate matter suspended in the River Severn (Shropshire, UK) consists chiefly of clay‐sized mineral particles, together with living and dead micro‐organisms (algae and bacteria). Its concentration depends strongly on discharge, but the particle size distribution shows no systematic variability. For most samples, the particle volume is log‐normally distributed with respect to diameter, the mean diameter being ca. 9 μm. The particles are mainly aggregates, including some with linear dimensions of the order of tens or hundreds of micrometres. Particle density depends appreciably on size, decreasing from ca. 2.5 × 106 g m−3 at a diameter of 2.5 μm to ca. 1.3 × 106 g m −3 at 20 μm. The collision efficiency factor for particle aggregation is estimated to be 0.01–0.03. At low discharge, the ‘dead zone’ in the River Severn at Leighton is a well defined region of stagnant water behind a gravel bar. The rate of deposition of fine particles on its bed is of the order of tens of grams per square metre per day. Resuspension requires a critical bed shear velocity of 0.03–0.04 m s−1, which occurs at main river discharges greater than about 150 m3 s−1. Under such conditions the gravel bar is underwater and the dead zone is a region of highly turbulent return flow. A simple mechanistic model of particle dynamics in the dead zone accounts reasonably well for particle accumulation rates when run with parameter values based on measured particle and hydraulic properties. Calculations with the model suggest that most of the sedimentation flux to the dead zone bed is due to particles with equivalent sphere diameters in the range 30–240 μm. Simulations indicate that deposition proceeded continuously during spring and summer, whereas repeated deposition and resuspension occurred in autumn and winter.
Hydrological flow paths at the allt A' mharcaidh catchment: An analysis of plot and catchment scale observations
Authors: Wheater H. S. , Tuck S. , Ferrier R. C. , Jenkins A. , Kleissen F. M. , Walker T. A. B. , Beck M. B. 
Published: February 2007

AbstractAn integrated programme of hydrological monitoring at the 10 km2 Allt 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 observations.
Streamflow routing in the indian arid zone
Authors: Sharma K. D. , Murthy J. S. R. , Dhir R. P. 
Published: February 2007

AbstractA lumped model for streamflow routing in arid ephemeral channels has been developed. The governing equations for movement of flood waves subjected to transmission losses are simplified through a time averaging process to develop an ordinary differential equation describing transmission losses as a function of distance, inflow, channel width, time parameters of flow and effective hydraulic conductivity. The resulting equation has an analytical solution and simulates runoff volume and peak discharge rates for individual storm events. The outflow hydrograph is fairly well approximated with a triangular approximation. The model is simplified and constructed to require a minimum of observed data for calibration. It can also be used for ungauged basins in arid regions through parameterization.
Distribution of caesium‐137 in soils across a hillslope hollow
Authors: Morris C. D. , Loughran R. J. 
Published: February 2007

AbstractThe distribution of soil 137Cs in relation to selected soil and landform properties was studied across a 16 ha hillslope hollow in the Hunter valley, New South Wales, Australia. The hillslope was used as grazing for cattle. Caesium‐137 was not significantly related to the amount of sand, silt, or clay, the bulk density, the organic matter content, the slope angle or the relative distance downslope. However, 137Cs was significantly related to the thickness of the soil A horizon. Spatial variations in 137Cs were compared with topographic units and a six‐element hillslope model, but there was little correspondence. It was thought that the effects of microtopography could have masked potential interrelationships between 137Cs and broader scale landform parameters.
Similarity analysis and scaling: An application to soil infiltration properties
Authors: Li Changxing , Shen Jin 
Published: February 2007

AbstractSimilarity and scaling theory are applied to soil physics, specifically to several parameters of unsaturated soil water movement. Following a dimensional analysis of Richards' equation, a mechanical similarity criterion of the hydraulic parameters is developed. Dimensionless factors which conform to assumptions of kinematic and dynamic mechanical similarity in the flow system are converted to relations using the scale factor a derived under the assumption of geometric similarity. As an example, the infiltration process is assessed through scaling of the parameters in Philip's equation, using experimental data from double‐ring infiltration measurements at 54 locations in a study catchment as the scaling test.
Hydrological and hydrochemical response of mountainous basins to snow accumulation and melting in northern slovakia
Authors: Babiaková G. , Bodiš D. , Palkovič D. 
Published: February 2007

AbstractHydrological and hydrochemical parameters for two mountain basins are presented and compared. The analysis focuses on the hydrology during the winter, the cumulative outflow of sulphate and nitrate from the basin and a mass balance. An integrated model for the simulation of the amount and quality of snowmelt from seasonal snow cover is briefly described. The possible application of the model to other basins is considered.
Capturing the essential spatial variability in distributed hydrological modelling: Infiltration parameters
Authors: Farajalla Nadim S. , Vieux Baxter E. 
Published: February 2007

AbstractSelecting the correct resolution in distributed hydrological modelling at the watershed scale is essential in reducing scale‐related errors. The work presented herein uses information content (entropy) to identify the resolution which captures the essential variability, at the watershed scale, of the infiltration parameters in the Green and Ampt infiltration equation. A soil map of the Little Washita watershed in south‐west Oklahoma, USA was used to investigate the effects of grid cell resolution on the distributed modelling of infiltration. Soil‐derived parameters and infiltration exhibit decreased entropy as resolutions become coarser. This is reflected in a decrease in the maximum entropy value for the reclassified/derived parameters vis a vis the original data. Moreover, the entropy curve, when plotted against resolution, shows two distinct segments: a constant section where no entropy was lost with decreasing resolution and another part which is characterized by a sharp decrease in entropy after a critical resolution of 1209 m is reached. This methodology offers a technique for assessing the largest cell size that captures the spatial variability of infiltration parameters for a particular basin. A geographical information system (GIS) based rainfall‐runoff model is used to simulate storm hydrographs using infiltration parameter maps at different resolutions as inputs. Model results up to the critical resolution are reproducible and errors are small. However, at resolutions beyond the critical resolution the results are erratic with large errors. A major finding of this study is that a large resolution (1209 m for this basin) yields reproducible model results. When modelling a river basin using a distributed model, the resolution (grid cell size) can drastically affect the model results and calibration. The error structure attributable to grid cell resolution using entropy as a spatial variability measure is shown.
Hydrochemical and water source variations across a floodplain mire, Insh Marshes, Scotland
Authors: Grieve Ian C. , Gilvear David G. , Bryant Robert G. 
Published: February 2007

AbstractGroundwater heads and chemical composition were measured at approximately two week intervals during the summer of 1993 along a 1 km transect across the Insh Marshes floodplain mire in Inverness‐shire, Scotland. Groundwater heads were generally higher near the valley side slope, with lower pH values and greater dissolved organic carbon, A1 and C1 concentrations. In the centre of the transect, upward groundwater heads were identified and pH, conductivity and concentrations of base cations were much greater. Near the River Spey, pH and base cation concentrations decreased and A1 and C1 concentrations increased. Deep groundwater followed a similar spatial trend but was generally more base‐rich than shallow groundwater. These variations reflect the influence of three major water sources with different chemical signatures. Runoff from the valley side slope increased dissolved organic carbon and A1 in the shallow groundwater, the upward flow of groundwater increased the pH and Ca concentration and inundation near the river decreased the base status and increased C1 and A1.
Effects of ice‐front collapse and flood generation on a proglacial river channel near kangerlussuaq (Søndre Strømfjord), west greenland
Authors: Russell Andrew J. , Van Tatenhove Frank G. M. , Van De Wal Roderik S. W. 
Published: February 2007

AbstractRiver discharge measurements downstream of the Russell Glacier, near Kangerlussuaq (Søndre Strømfjord), West Greenland revealed the occurrence of short‐term discharge fluctuations during the 1991 melt season. Frontal ice‐cliff collapse results in temporary river damming, producing initial decreases in discharge and subsequent sudden flood peaks on dam failure. Fluctuations are less than two hours in duration, with a maximum discharge fluctuation magnitude of 50m3s−1, double that of normal ablation‐controlled diurnal fluctuations. As such, these events are exceeded in magnitude only by periodic jökulhlaups resulting from the drainage of an ice‐dammed lake further up‐glacier. The concentration of discharge fluctuations at the beginning of the melt season, the large number of ice blocks within the flow and the confinement of flows between ice block levees all add to the effectiveness of these events in terms of channel erosion and sediment transport.
A process‐based model for colluvial soil depth and shallow landsliding using digital elevation data
Authors: Dietrich William E. , Reiss Robert , Hsu Mei‐Ling , Montgomery David R. 
Published: February 2007

AbstractA model is proposed for predicting the spatial variation in colluvial soil depth, the results of which are used in a separate model to examine the effects of root strength and vertically varying saturated conductivity on slope stability. The soil depth model solves for the mass balance between soil production from underlying bedrock and the divergence of diffusive soil transport. This model is applied using high‐resolution digital elevation data of a well‐studied site in northern California and the evolving soil depth is solved using a finite difference model under varying initial conditions. The field data support an exponential decline of soil production with increasing soil depth and a diffusivity of about 50 cm2/yr. The predicted pattern of thick and thin colluvium corresponds well with field observations. Soil thickness on ridges rapidly obtain an equilibrium depth, which suggests that detailed field observations relating soil depth to local topographic curvature could further test this model. Bedrock emerges where the curvature causes divergent transport to exceed the soil production rate, hence the spatial pattern of bedrock outcrops places constraints on the production law.The infinite slope stability model uses the predicted soil depth to estimate the effects of root cohesion and vertically varying saturated conductivity. Low cohesion soils overlying low conductivity bedrock are shown to be least stable. The model may be most useful in analyses of slope instability associated with vegetation changes from either land use or climate change, although practical applications may be limited by the need to assign values to several spatially varying parameters. Although both the soil depth and slope stability models offer local mechanistic predictions that can be applied to large areas, representation of the finest scale valleys in the digital terrain model significantly influences local model predictions. This argues for preserving fine‐scale topographic detail and using relatively fine grid sizes even in analyses of large catchments.
Catchment‐scale runoff generation model by aggregation and similarity analyses
Authors: Robinson Justin S. , Sivapalan Murugesu 
Published: February 2007

AbstractRunoff generation in natural catchments due to storm rainfall is highly complex and spatially and temporally heterogeneous. In recent work on seven small experimental catchments Larsen et al. (1994) showed that underlying the heterogeneity of runoff generation within the catchments, there is a degree of regularity between the catchments that could be quantified in terms of two dimensionless similarity parameters K0* and f*. These two parameters, constants for a catchment, were able to characterize the relative dominance of the saturation excess (Dunne‐type) and infiltration excess (Horton‐type) mechanisms of runoff generation. Given that K*0 and f* can characterize the type of runoff generation on any catchment, it may follow that they can be used to define a catchment‐scale runoff generation model. This idea is pursued in this paper. For the same catchments as studied by Larsen et al. (1994), a lumped, physically based model is developed that describes both the extent of saturated areas and the average infiltration capacity of the unsaturated areas during a storm. This is achieved by utilizing the distributed model used by Larsen et al. (1994) to aggregate the point‐scale runoff generation responses, up to the catchment scale, from which the functional form and the parameters of the catchment‐scale runoff generation model are inferred. The parameters of this lumped model are defined entirely in terms of the underlying distribution of topography, three similarity parameters K*0, f* and B*, the normalized average water‐table depth, z*, and the normalized cumulative volume of infiltration, G*.