bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon dioxide in cave atmospheres. New results in belgium and comparison with some other countries
Authors: Ek Camille , Gewelt Michel 
Published: February 2007

AbstractMore than 600 measurements of the carbon dioxide content of cave air in Belgium lead up to the conclusion that the main factors of its distribution are: (1) a flow originating from the biomass and diffusing in the soil and the voids of bedrock; (2) a trend, discernible in very still air only, to go down by density; (3) in some caves, draughts caused, for instance, by a swift underground stream.Results in Belgium are compared with published and unpublished data from other countries, showing that CO2 is often less abundant in cold climate caves and in caves of semi‐arid regions (influence of the biomass).Special attention is paid to human contamination during analyses: the influence of people passing through the cave nearby the operator, but also the influence of the operator himself are discussed, and the use of special precautions (including a CO2‐absorbing mask) in defined critical situations is stressed.
Lichenometric dating of debris‐flow deposits on alpine colluvial fans in Southwest Norway
Authors: Innes John L. 
Published: February 2007

AbstractLichenometry provides a suitable means of dating recent debris‐flow activity on alpine colluvial fans. Existing growth curves can be used, provided that anomalous thalli are excluded and allowances are made for differences in the growth rates of Rhizocarpon alpieola and Rhizocarpon section Rhizocarpon thalli. The distribution of flow deposits through time is non‐random and two periods of increased activity (1670‐1720 AD and 1790‐1860 AD) can be identified. There is no evidence for a large increase in debris‐flow activity in the late 19th century, as has been found in Scotland. This can be attributed to the absence of detrimental landuse practices in the Norwegian study areas.
Estimation of the mean velocity of particulate flows by counting
Authors: Culling W. E. H. 
Published: February 2007

AbstractUsing Smoluchowski's theory of the probability after‐effect it is possible to estimate the mean speed or velocity of a particulate flow by counting the number of particles present in a selected region at a sequence of equal time intervals. Apart from a knowledge of the dimensions of the region the only conditions are that the process is, in a wide sense, stationary and that the speeds of individual particles are independent. Subsequent refinements and extensions to the theory by Furth, Ruben, Rothschild and Lindley are incorporated to provide a method of velocity estimation of wide application in geomorphology. Finally, a numerical example on pedestrian speeds is assessed against an independent estimate.
Petrological influence on differential weathering and inselberg development in the Kora area of central Kenya
Authors: Pye K. , Goudie A. S. , Watson A. 
Published: February 2007

AbstractIn the Kora area of central Kenya domed inselbergs are well developed on outcrops of granitoid migmatite, while positive relief features are rare on the surrounding gneiss. Block‐strewn, vegetated hills occur on restricted areas of granoblastite, gabbro, and metagabbro. Schmidt Hammer measurements have shown that the apparent differences in resistance to weathering and erosion are not due to variations in rock hardness, since all the rock types have similar ‘R’ values. The results of geochemical analyses have shown that the migmatites are significantly more potassic than the surrounding gneiss. Samples of migmatite from the inselbergs were also found to be slightly richer in potassium than migmatite samples from the inter‐inselberg areas. The variations in potassium content probably reflect differences in protolith composition, chemical fractionation during partial melting, and the effects of metasomatism. These findings support earlier suggestions that, other things being equal, potassium‐rich granitoid rocks weather more slowly than less potassic rocks.
Tunnel formation processes in the Riverina area of N.S.W., Australia
Authors: Crouch R. J. , McGarity J. W. , Storrier R. R. 
Published: February 2007

AbstractSoil and site characteristics associated with tunnel erosion are diverse. This contributes to difficulties in identifying areas of potential tunnelling and the reclamation of land affected by this form of water erosion. Soil, site, and tunnel characteristics at three locations having different morphological expressions of this erosion form were examined to determine which features were important in tunnel development in the Riverina Area of N.S.W., Australia.Soil dispersion was a dominant process at each site and is related to high levels of exchangeable sodium. Field and laboratory studies demonstrated the importance of dispersion and its effect on water movement, particle transport, and subsequent tunnel initiation.Tunnel initiation mechanisms differed between the sites but could be identified by morphological examination of the tunnels. Potential tunnel eroding sites are characterized by a dispersible layer, a gradient for water flow, and soil characteristics that promote water Sow in defined paths. Appropriate control techniques need to be formulated for each differing form of tunnel erosion.
Geomorphological evolution of a Lowland valley system during the Weichselian
Authors: Van Huissteden J. , Van Der Valk L. , Vandenberghe J. 
Published: February 2007

AbstractWeichselian geomorphological and fluvial evolution has been recorded in the valley fill of the Reusel, a small tributary of the lower Maas river. It has been studied by means of borehole sections. A first deep incision into the substratum occurred during the Early Weichselian‐Lower Pleniglacial. This was followed by aggradation, at first by a braided river, at a later date by a meandering river, dating respectively from the Lower and Middle Pleniglacial. The Upper Pleniglacial aggradation again points to a braided river system. The end of the Pleniglacial is characterized by aeolian infilling of the valley and decreasing carrying capacity of the river.
A comparison of element outputs in solution, suspended sediments and bedload for a small upland catchment
Authors: Reynolds B. 
Published: February 2007

AbstractThe individual outputs of several elements in solution, suspended solids and bedload were estimated for a stream draining a small upland catchment in mid‐Wales. The data indicate the overall importance of transport in solution, although the solid phase can make a significant contribution to the export of potassium, iron and silicon from the site.
Laboratory simulation of ‘the wick effect’ in salt weathering of rock
Authors: Goudie A. S. 
Published: February 2007

Abstract‘The wick effect’ is the upward migration of saline solutions into rocks and their subsequent crystallization. Lower Carboniferous sandstone blocks of rectangular shape have been subjected to this process in the laboratory using a range of salt types, a range of salt concentrations, and various mixtures of salts. Some treatments produced severe disintegration, notably sodium carbonate and a mixture of sodium carbonate with magnesium sulphate, whereas other salts (including sodium chloride and gypsum) were much less effective. The debris produced by this experimental salt weathering included appreciable quantities of silt‐sized material, which were analysed with a laser granulometer. Such material could provide a source for desert loess.
A morphodynamic model for beach gradients
Authors: Hardisty J. 
Published: February 2007

AbstractThis paper outlines a general framework for analysis of the problem of beach gradients which divides the system into: (1) the independent controls, (2) the hydrodynamics, (3) the sediment dynamics, and (4) the morphodynamics. A model is derived from the combination of these stages which shows close agreement with field data for wave steepnesses of less than about 0.06, but predicts lower beach gradients than arc observed for steeper waves. The use of ‘analytical feedback’ in the present model rather than the ‘iterative feedback’ which is used in computer simulations demonstrates that differential sediment transport may be responsible for stabilizing the beach gradient.
Erosional and chemical denudation rates in the Southwestern Idaho batholith
Authors: Clayton James L , Megahan Walter F 
Published: February 2007

AbstractAnnual erosional denudation (ED) and chemical denudation (CD) rates are determined on four forested watersheds located in the Idaho batholith, Idaho, U.S.A. Bedrock in the study area is a coarse‐grained quartz monzonite. Annual sediment yields are computed from sediment collected in settling ponds at the watershed mouths and corrected for trapping efficiency. Solution loads for denudation components (Na, K, Ca, Mg, SiO2, A12O3 and FeO) are computed using equations relating concentration to flow and by integration of mean daily flow values. Eleven years of water chemistry data and 19 to 23 years of sediment yield data are used in the denudation estimates. Strong relationships exist between CD, ED and annual water yield, so probability distributions of annual water yield are used in Monte Carlo simulations to establish frequency distributions of annual CD and ED rates.Mean annual total denudation for the four watersheds (CD + ED) equals 235 kg ha −1 yr−1 or 8‐9 Bubnoffs. The 11 ‐year mean ED rates exceed CD rates for three of the four watersheds, although it is more probable in any given year that CD will exceed ED for three of the watersheds. ED is temporally more variable than CD for all watersheds. Simulations of denudation over 1000‐year periods indicate that the frequency of occurrence of ED is skewed toward higher denudation values, and the modal ED rate is substantially lower than the mean value. CD rates are less skewed, with mean and mode in the same class. Ninety‐seven per cent of CD is composed of Na, Ca and SiO2 fluxes. Episodic high ED rates are related to high peak flows from snowmelt runoff associated with winters of large snow accumulation. Perturbations such as fire or road construction would be expected to accelerate ED more than CD.
Depositional process and alluvial fan‐drainage basin morphometric relationships near banff, Alberta, Canada
Authors: Kostaschuk R. A. , Macdonald G. M. , Putnam P. E. 
Published: February 2007

AbstractTwo distinct types of alluvial fans occur in the Bow River Valley, Alberta, Canada: fluvially dominated and debris flow dominated. Large, gently sloping fans dominated by fluvial processes are associated with large and less rugged drainage basins, and small rugged basins have produced small, steep fans dominated by debris flow processes. Quantitative analysis demonstrates that strong fan‐basin morphometric relationships occur despite a short fan history.Statistical analysis of fan area‐basin area relationships indicate that debris flow fan areas do not increase in size as quickly as contributing basins. The relationship of fluvial fan area to basin area is not statistically significant. However, this relationship is probably affected by fan erosion. Examination of fan slope to basin ruggedness relationships indicates that fan slope increases more rapidly than basin ruggedness for both fan types. This is likely related to non‐linear discharge and sediment size effects on fluvial fans, and reworking of larger fan surfaces by fluvial processes on debris flow fans.
Estimating wind transport of sand on vegetated surfaces
Authors: Wasson R. J. , Nanninga P. M. 
Published: February 2007

AbstractVegetation significantly reduces the transport of sand by wind. We report a generalization of Bagnold's transport equation by finding empirical mathematical expressions to describe the relationships between projected vegetation cover, wind speed outside the area of vegetation, and transport rates. Examples of the use of the equations are given, illustrating the effect of vegetation cover on sand transport, dune encroachment and soil nutrient loss during individual wind storms and over periods of many years.
Field measurement of the velocity of overland flow using dye tracing
Authors: Abrahams Athol D. , Parsons Anthony J. , Luk Shiu‐Hung 
Published: February 2007

AbstractA new method of computing the mean velocity of overland flow using dye tracing is proposed in which a specified cross‐section is divided into zones of relatively uniform flow characteristics, termed partial sections. The mean surface velocity for each partial section is determined by timing the passage of injected dye, and this figure is multiplied by 0.67, 0.70, or 0.80, depending on whether the flow is laminar, transitional, or turbulent, to give mean velocity. The mean velocity for the entire cross‐section is calculated by multiplying the mean velocity of each partial section by its cross‐sectional area, summing the products for all the partial sections, and dividing by the total area of the cross‐section. A field test shows that mean velocity derived in this manner differs from mean velocity derived by the discharge method (i.e. by dividing discharge measured volumetrically by cross‐sectional area) by an average of only 7.07 per cent. Thus the partial‐section technique appears to provide a reliable method of estimating mean velocity of overland flow.
The characteristics and significance of some lateglacial protalus ramparts in upland Britain
Authors: Ballantyne Colin K. , Kirkbride Martin P. 
Published: February 2007

AbstractArcuate and linear protalus ramparts of inferred Loch Lomond Stadial age are widespread in upland Britain outside the limits of contemporaneous glaciers. Survey and analysis of the morphology of nine ramparts suggests that these may have formed at the foot of slowly thickening snowbeds, with rockfall debris accumulating against their distal slopes, and that snowbed melting at the end of the stadial was uninterrupted by prolonged periods of stability or renewed growth. Rampart sediments consist of poorly‐sorted assemblages of clasts with a variable infill of fines. Clast size and shape are strongly influenced by lithology, but rampart clasts are characteristically more angular and ‘slabbier’ than those of similar lithology in ice‐marginal moraines. Ramparts may also be distinguished from moraines by their location, morphology, lack of a true matrix of fines and absence of erratics, and from talus‐foot rock glaciers in terms of their width and the absence of flow structures. The mapped distribution of rampart altitudes across the Scottish Highlands displays a marked regional trend, with the lowest features in the west and south and highest in the Cairngorms. This pattern mirrors that of reconstructed firn line altitudes of Loch Lomond Stadial glaciers, and is inferred to reflect a pronounced eastwards and northwards decline in snowfall during the stadial.
The hurst effect and its implications for extrapolating process rates
Authors: Kirkby M. J. 
Published: February 2007

AbstractIn long‐term records of climatic or hydrological events, persistent periods of high and low values are measured by the ‘rescaled range’, which is defined for a sequence of n consecutive values. As n increases the rescaled range for historic sequences increases as nH for 0·5 < H < = 1. This is the Hurst effect. Sequences of independent random events give H = 0·5, while sequences in which the values are successive positions of a random walk (i.e. the sum of independent events) give H = 1. Intermediate values of H may be obtained from fractal sequences, from sequences with a steadily changing mean, or through a storage model. In all but the fractal case H exceeds 0·5 for a time related to the duration of the changing mean or the response time of the store.An exponential storage model has been explored in some detail. Storage models have the advantage of offering a plausible physical mechanism for persistence. Analysis of simulated sequences shows that the Hurst effect is evident for about 30 x the response time of the store, so that relatively modest store sizes are enough to explain observed Hurst effects over available periods of record. Comparison with empirical values shows that high H values seem to be associated with large physical stores.Whether the Hurst effect is due to storage effects or climatic or other change imposed from outside, the effect on longterm process rates is strong. Short‐term measurements of process rates show compressed variances and simple extrapolation is likely to produce large errors. If it is assumed that long‐term rates are strongly influenced by climatic variables, then measurements may be used to obtain parameters of a climatic model for differences in process rates. Errors in extrapolation will be least where the model has a sound physical basis.A first implication for magnitude and frequency distributions is that the sequence of events may be as important as their distribution over time in determining process impact. A second conclusion is that the geomorphic history of an area is inevitably dominated by a sequence of larger and larger events receding into the past, and that the Hurst exponent over geologic time‐spans measures the extent of that domination.
On the frequency distribution of land slope
Authors: P. O'Neill Michael , Mark David M. 
Published: February 2007

AbstractSlope frequency distributions are computed from Digital Elevation Models (DEMs) of 18 areas from five different geographic and physiographic regions. Over 160,000 slope estimates are used in the definition of the slope frequency distribution for each area. Analysis of several transformations of the slope data indicates that no single transformation is capable of normalizing all slope distributions. This is, in part, due to the arbitrary placement of the boundaries of the map sheets used in the data collection. The square root of sine, however, provides better results than sine, log‐tangent, or several other transformations. The degree of (positive) skewness of gradients in degrees correlates with the proportion of slopes below 2° or 5° (rs = + 0·93), as does the kurtosis (rs = + 0·91).
An upland soil erosion model derived from the basic principles
Authors: Sharma K. D. , Correia J. F. 
Published: February 2007

AbstractStarting from the basic erosion principles, an upland soil erosion model to predict soil loss by overland flow from individual storms on forested hillslopes can be derived in the form

where Qs is total soil loss for a storm event, n is roughness coefficient, x is down slope distance, Kf is soil erodibility factor, S is slope, α is slope exponent and Q is runoff. Values of n and α are to be determined for different environments and are 0·58 and 2·1 for a mixed pine forest ecosystem. A significant correlation (r = 0·933, n = 96) fits between the observed and predicted values using this expression, and the model fitting is good.
Copper dispersion in ephemeral stream sediments
Authors: Andrew Marcus W. 
Published: February 2007

AbstractSediment transport related parameters in ephemeral streams may be used to model and delineate: (1) average dispersion patterns of copper‐laden sediments; (2) differences in dispersion of copper in bedload and suspended sediments; and (3) variability in the copper‐sediment dispersion patterns. A model that effectively describes dispersion of copper in ephemeral stream sediments in a simple mixing model:

where Cr is the resultant concentration beneath the confluence of the main channel with a tributary, Ct is the concentration of metal in sediments of the tributary, Cm is the metal concentration in main channel sediments, and Xm and Xt are the basin areas or sediment yields of the main channel and tributary channel at their confluence. Variability in metal concentrations about values predicted by this model may be due to the different responses of bedload and suspended load to changes in stream hydraulics, the dynamics of bedload transport, the spatial and temporal variability rainfall within the drainage basin, and chemical mobility of the copper.
210pb as a chronometer and tracer, Burrinjuck Reservoir, Australia
Authors: Wasson R. J. , Clark R. L. , Nanninga P. M. , Waters J. 
Published: February 2007

AbstractCores taken at Burrinjuck Reservoir in southeastern New South Wales have been dated using the first appearance of 137Cs, charcoal/bushfire correlations, and annual grass pollen peaks. None of the main 210Pb dating models reproduced the ‘known’ chronology. Correlation analysis shows no significant relationship between original 210Pb (unsupp.) concentration and grain‐size, sedimentation rate or loss on ignition. Differences in sediment source may explain the variations in 210Pb. A simple provenance model has been used to interpret the ratio of original 210Pb (unsupp.)/226Ra as a tracer of topsoils and subsoils. High ratios in the reservoir sediments probably indicate eroded topsoils and low ratios eroded subsoils.
Debris flow during intense rainfall in Snowdonia, North Wales: A preliminary survey
Authors: Addison Kenneth 
Published: February 2007

AbstractIntense rainfall after the abnormally dry and warm summer of 1983 triggered debris flows in mountainous terrain in North Wales. This preliminary investigation concentrates on a flow which blocked the A5, requiring £56,000 of remedial work. An estimated 118·4 mm of rain fell over steep, rocky catchments in 5 hrs (peak intensity 39·9 mm hr−1) and water emerging from a rock chute mobilized colluvium on lower slopes, in which pore water pressure was probably already rising fast and bulk properties and other geotechnical conditions, including low shearing resistance, were favourable. Debris flowed in a narrow concave track 585 m long, x slope 27·8°, descending 282 m. The scoured channel, levées and debris lobes typical of documented flows elsewhere suggest that flow was rapid, turbulent, and pulsing.
Identification of strength equilibrium rock slopes: Further statistical considerations
Authors: Abrahams A. D. , Parsons A. J. 
Published: February 2007

AbstractStrength equilibrium slopes are rock slopes whose gradient θ and rock mass strength (RMS) are in adjustment. The identification of such slopes depends on the accurate specification of the strength equilibrium envelope. Previous attempts to delimit the envelope are reviewed and modifications are proposed that permit its more rigorous statistical definition. Because θ can be measured much more reliably than RMS, the structural relation between these variables is estimated by regressing RMS on θ, and the strength equilibrium envelope is defined by the 95 per cent confidence limits. The analysis is performed on a data set of 268 rock slopes, representing all the data on RMS and θ hitherto employed in published studies of strength equilibrium slopes.
Sediment yield in the upper Krishna Basin, Maharashtra, India
Authors: Gole S. P. , McManus J. 
Published: February 2007

AbstractA 235.5 km2 headwater catchment of the Krishna River in the Deccan plateau lavas is dry for eight months of the year but receives intense monsoonal rains during four months. High initial suspended sediment concentrations fall as rapid vegetation growth provides increasing protection. During a six‐year period annual suspended sediment yields from the deeply weathered kaolinitic soils ranged between 36.9 and 275.3 t km−2 in dry and wet years respectively.