bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of waste spoils in an area strip mine—geological and geotechnical considerations
Authors: Okagbue C. O. 
Published: February 2007

AbstractResults of investigations into the stability of coal mine spoil consisting of thick clay, saturated sand, and shale overburden in an areal strip mine are presented. Atterberg limits, particle size distributions, and compaction tests were performed to provide index characteristics of the materials. Unconsolidated undrained and consolidated undrained triaxial compression test results on 10·2 cm diameter samples of compacted shale and shale‐soil mixtures were used to investigate the short‐term and the long‐term conditions respectively of the spoil slope.There is evidence that the failure envelope of mine spoil made up of shale or shale‐soil mixture is curved. However, stability analyses reveal that the use of strength parameters defined by a linear Mohr‐Coulomb envelope yields results that are comparable with those obtained when the non‐linear failure envelope is used, provided that such strength parameters are defined at the operating normal stress level on the failure surface.The study illustrates a very good case of spoil instability resulting from very thick overburden soils of low strength and high water content. Results show that the key to achieving stability in such areas lies in an almost total segregation of the soils from the rocks.
A field experiment on the role of small scale wind gustiness in aeolian sand transport
Authors: Lee Jeffrey A. 
Published: February 2007

AbstractEstimates of aeolian sand transport generally use an average wind speed to assess the wind energy. To determine if variation in small‐scale wind gustiness (on the order of several seconds duration) has a significant effect on sand movement, detailed field measurements were made of wind speed and transport rate. Average wind speed and several gust parameters were derived from the wind data. The results indicate that small‐scale gust information does not improve prediction of transport rates.
The fractal geometry of the soil—covered landscape
Authors: Culling W. E. H. , Datko Mark 
Published: February 2007

AbstractThe soil‐covered landscape surface can be idealized from two viewpoints. The intuitive view is of a smooth, absolutely continuous surface with continuous contour lines and measurable in integral dimensions. The alternative view emphasizes the roughness, a surface of little regularity and at the limit of no contours, the appropriate measure being that of fractional Hausdorff dimension. Regularity is a local property and both idealizations need to stop far short of the limit to avoid awkward consequences.The dichotomy of viewpoint can be matched in the theory of Gaussian random fields. These, if they are smooth, are very smooth but if they are irregular they are highly irregular (erratic); there is no middle ground. This Belayev dichotomy is defined and both modes applied to the soil‐covered landscape. On the one hand, if the landscape is subject to a general diffusive type degradation or more generally a Davisian downwasting regime then the curvature of the landscape surface is progressively straightened and the distribution of gradient (increments) along a typical traverse will eventually adopt a Gaussian form. Then from the irregular viewpoint the surface is ultimately well represented by a fractional Brownian surface of low Hausdorff dimension (2·0 < dim < 2·3). The Hausdorff dimension is directly related to the entropy of the landscape and as degradation proceeds both quantities decrease in value.On the other hand, if the surface is regarded as smooth and well represented by an absolutely continuous Gaussian field then the mean value of the number of upcrossings of a level or the extent of an excursion set will also be Gaussian. This analysis is restricted to one dimension; the number of times a profile curve crosses or the amount of time it spends above any given level.Predictions from both viewpoints are substantially corroborated in a map analysis of 15 sites on varied terrains in Southern England and the map analysis checked against one based upon digital tape data for one of the sites.
Patterns of dissolved organic matter in subarctic peatlands
Authors: Moore T. R. 
Published: February 2007

AbstractSamples of water from poor to very rich fens in the Schefferville region of subarctic Quebec revealed strong spatial and temporal variations in dissolved organic carbon (DOC), ranging from 2 to 40 mg 1−1. Concentrations of DOC tend to increase during the summer and decrease in the autumn, at most sites, which probably reflects increased plant tissue decomposition and higher rates of evapotranspiration. Principal components analysis revealed that DOC is strongly associated with Fe, NO−3‐N and NO−2‐N, but essentially independent of other chemical properties of the peat water, such as pH, Ca, Mg, K, P, and NH+4‐N. Based on observed concentrations of DOC and estimates of summer runoff (June to September), export of DOC from four peatlands ranges from 1·1 to 4·9 gCm−2, with the lowest values for peatlands underlain by dolomite. Molecular weight fractionation of four samples revealed significant differences in the dissolved organic matter (DOM), with the largest fractions (GF/C to 10 000 nmw) being dominant in the more acid samples. The ratio of absorbance at 400 and 600 nm wavelengths (E4:E6) has been used as a simple indicator of differences in DOM type, ranging from 3 to 15. There is a strong seasonal pattern of increasing E4:E6 ratio during the summer at many sites, though this ratio is essentially independent of other chemical properties of peat waters.
Dust storms and related phenomena measured from meteorological records in Australia
Authors: McTainsh G. H. , Pitblado J. R. 
Published: February 2007

AbstractUsing meteorological records (1957–1984) in Australia, formal definitions are proposed of four types of dust event: dust storms, blowing dust, dust whirls, and dust haze. Australia‐wide maps of the extent of these four dust event types are presented.
Absolute dating by uranium series disequilibrium of bones from the cave of La Chaise‐de‐Vouthon (Charente), France
Authors: Rae Angela M. , Ivanovich Miro , Schwarcz Henry P. 
Published: February 2007

AbstractAnimal bones, associated with Palaeolithic artefacts and skeletal remains of early hominids from the cave of La Chaise‐de‐Vouthon, have been dated using a new approach to uranium series dating of bone. Speleothem (cave calcite) interstratified with bone‐bearing sediments in the two chambers of Grotte Bourgeois‐Delaunay and Grotte Suard have previously been dated by the 230Th/234 U method. This provides a chronological control for the bone ages, for which the method is still at an experimental stage. A good agreement is shown in most cases between the calcite and the bone ages, showing the cave to have been a stable environment for the deposition of bone and the acquisition of uranium.
An evaluation of the use of size distributions of sediment in runoff as a measure of aggregate breakdown in the surface of a cracking clay soil under rain
Authors: Loch R. J. , Cleary J. L. , Thomas E. C. , Glanville S. F. 
Published: February 2007

AbstractTwo rainfall simulators of different plot sizes were used to test whether sediment in runoff could be used to measure aggregate breakdown in the surface of a cracking clay soil under rain. Plots were prepared with either levelled or furrowed surfaces. Samples of the soil surface under rain were taken from furrow ridges or levelled surfaces, and from areas of deposited sediment. These were compared with samples of sediment in runoff taken at the same times. On both furrowed and levelled plot surfaces and for both simulators, aggregate sizes were significantly finer in sediment in runoff than in samples of the soil surface taken with a spatula. No significant differences in surface aggregate size distributions were found between rainfall simulators, or between furrowed and levelled plot surfaces. Regression lines fitted to the data on size distributions of sediment or of aggregates in the soil surface showed no significant changes through time. The fitted lines showed sediment in runoff to be still significantly finer than aggregates in the soil surface after 50 min rain at 95 mm h−1, except for levelled plots under the rotating disc rainfall simulator, where extreme variability of data meant that even relatively large differences were not statistically significant. Size distributions of deposited sediment were similar to those of the surface of adjacent furrow ridges exposed to raindrop impact. This provides evidence that sampling the soil surface with a spatula gives a representative sample of the material available for rain‐flow transport.
A simulation model of wind erosion and sedimentation as a basis for management of a drift sand area in The Netherlands
Authors: Castel I. I. Y. 
Published: February 2007

AbstractA simulation model of sand transport by wind is developed to predict the future development of an active aeolian drift sand area in the central part of The Netherlands. The model is based on Bagnolds' sand transport equation, adapted for influence of the vegetation. The results of the simulation indicate that only little sand transport can be expected under present‐day climatic conditions. Consequently the mobility of the dunes can only be guaranteed by special management measures like locally removing all vegetation.
Scale model simulations of the deposition of loess in Hilly Terrain
Authors: Goossens Dirk 
Published: February 2007

AbstractThe sedimentation of loess in a 40 km2 area on the northern border of the Belgian loess belt, is investigated by means of wind tunnel experiments. Loess deposition is simulated on a relief scale model for different wind directions. It appears that simulation with northeast winds produces a loess deposition pattern that coincides closely to the field pattern, which may be an indication that the loess‐bearing winds at the end of the Weichselian came from the northeast.Loess deposition occurs preferably on windward slopes and not on leeward ones. The wind‐shadow concept, which is important in the case of sand deposition, may therefore not necessarily apply to fine materials such as fine silt and clay.
The use of ‘rock hard’‐sodium sulphate tablets for quickly determining preferential water flow routes in soils
Authors: Renshaw C. E. 
Published: February 2007

AbstractSubsurface water flow routes have been inferred from gypsum sphere weight loss with minimal disturbance to soil structure or flow nets (Crabtree and Trudgill, 1984). This technique is limited by the relatively slow, fixed dissolution of gypsum. A solution is to use tablets consisting of Durham's ‘Rock Hard Water Putty’ and sodium sulphate. Laboratory tests indicate that tablet dissolution is controlled by the ratio of Rock Hard to sodium sulphate and is proportional to net throughflow yet independent of throughflow pH (between 3·0 and 9·0) and throughflow rate (at rates < 0·04 1 hr−1). The tablets are also mechanically stable, economical, and environmentally safe. Field study results using the Rock Hard‐sodium sulphate tablets are consistent with both the laboratory findings and the results of previous investigators.
Hydraulics of sediment‐laden sheetflow and the influence of simulated rainfall
Authors: Gut B. T. , Dickinson W. T. , Rudra R. P. , Wall G. J. 
Published: February 2007

AbstractLaminar sheetflows, transporting sediment at their capacity rates, both with and without rainfall disturbance, were investigated. Values of flow depth and relative submergence were very small. In the flows without rainfall, measured velocities exceeded the predictions of the smooth‐surface, clear‐water laminar model by an average of 12 per cent. Reduced flow resistance due to high sediment concentrations may explain this result. Velocities in the rainfall‐disturbed flows were not significantly different from the predictions of the smooth‐surface, clear‐water model, and the velocity reduction due to rainfall was about 12 per cent. Although the uniformity of rainfall intensity under the single‐nozzle rainfall simulator is high, variation of momentum and kinetic energy fluxes along the 1‐5 m long flume was significant. The rainfall angle of incidence was highly correlated with deviations from expected flow velocities in the upper and lower sections of the flume.
Flood hydrology and geomorphic effectiveness in the central Appalachians
Authors: Miller Andrew J. 
Published: February 2007

AbstractThis paper compares hydrologic records and geomorphic effects of several historic floods in the central Appalachian region of the eastern United States. The most recent of these, occurring in November 1985, was the largest ever recorded in West Virginia, with peak discharges exceeding the estimated 500‐year discharge at eight of eleven stations in the South Branch Potomac River and Cheat River basins. Geomorphic effects on valley floors included some of the most severe and widespread floodplain erosion ever documented and exceeded anything seen in previous floods, even though comparable or greater rainfall and unit discharge have been observed several times in the region over the past 50 years. Comparison of discharge‐drainage area plots suggests that the intensity and spatial scale of the November 1985 flood were optimal for erosion of valley floors along the three forks of the South Branch Potomac River. However, when a larger geographic area is considered, rainfall totals and discharge‐drainage area relationships are insufficient predictors of geomorphic effectiveness for valley floors at drainage areas of 250 to 2500 km2.Unit stream power was calculated for the largest recorded flood discharge at 46 stations in the central Appalachians. Maximum values of unit stream power are developed in bedrock canyons, where the boundaries are resistant to erosion and the flow cross‐section cannot adjust its width to accommodate extreme discharges. The largest value was 2570 W m−2; record discharge at most stations was associated with unit stream power values less than 300 W m−2, but more stations exceeded this value in the November 1985 flood than in the other floods that were analysed. Unit stream power at indirect discharge measurement sites near areas experiencing severe erosion in this and other central Appalachian floods generally exceeded 300 W m−2; reach‐average values of 200‐500 W m−2 were calculated for valleys where erosion damage was most widespread. Despite these general trends, unit stream power is not a reliable predictor of geomorphic change for individual sites. Improved understanding of flood impacts will require more detailed investigation of interactions between local site characteristics and patterns of flood flow over the valley floor.
Erosion processes and rates for gullies in granitic soils bathurst, new south wales, australia
Authors: Crouch R. J. 
Published: February 2007

AbstractSoil movement rates from fluted gully sides in New South Wales were measured over three years by erosion pins and survey. Erosion rates varied considerably over short distances from 0 to 53 mm yr−1 with an average removal rate of 19‐8 mm yr−1.
Rates and mechanisms of discontinuous gully erosion in a red‐brown earth catchment, new south wales, australia
Authors: Crouch R. J. 
Published: February 2007

AbstractRainfall, runoff, sediment discharge, and gully expansion were measured for five years in a small (45 ha) catchment in central N.S.W. Sixty per cent of the sediment produced from this catchment originated from gully erosion. Gully head erosion was episodic depending on pipe development, cracking, and soil detachment during small runoff events which prepared the heads for rapid soil movement by the infrequent large event.
The flank margin model for dissolution cave development in carbonate platforms
Authors: Mylroie John E. , Carew James L. 
Published: February 2007

AbstractThe Bahama Islands contain many abandoned dissolution caves at elevations between two and seven metres above current sea level. The development of dissolution caves in tropical carbonate islands is dependent on the position and nature of the freshwater lens. Lens position is controlled by sea level, which in stable carbonate platforms like the Bahamas is a function of glacioeustatic sea level still stands. Caves in the Bahamas that are currently subaerial must have developed during past higher sea levels. During the Late Quaternary, sea levels higher than present have been relatively short‐lived, and that limits the amount of time that a freshwater lens could be situated at the elevation required for the cave formation. The Bahama Islands are low‐lying landforms where only aeolian ridges extend to elevations higher than six metres above current sea level. Past high sea level events greatly reduced the exposed land area of the Bahama Islands, thus also limiting both the catchment for and size of freshwater lenses. Caves must be younger than the rock in which they are developed; most subaerial Bahamian caves are found in limestones that are less than 150000 years old. Development of large dissolution caves under these limitations of time and lens size requires a powerful dissolutional mechanism. The mixing of discharging freshwater with tide‐pulsed incoming marine water under the flanks of emergent dune ridges may have produced the conditions necessary. Bahamian caves formed by this process are phreatic chambers with complex interconnections and blind tubes. Their presence demonstrates that significant dissolution can occur rapidly as a result of the mixing of fresh and marine waters beneath small carbonate islands.
A comment on ‘enhanced boulder weathering under late‐lying snow patches’ by ballantyne, C. K., Black, N. M., and Finlay, D. P.
Authors: McCarroll Danny 
Published: February 2007

AbstractBallantyne et al. (1989) compare Schmidt hammer results from late‐lying snowpatches with adjacent snow‐free control sites and claim that their results lend ‘strong and unequivocal support to the concept of enhanced weathering under late‐lying snowpatches’. However, the data presented from sites of different age but in the same area suggest that the difference in results between snowpatch and control sites is unlikely to reflect differences in degree of boulder surface weathering. Their statistical treatment of the data also lends exaggerated significance to rather small absolute differences and obscures between‐boulder variability within sites.
Palaeovelocity: A parsimonious proposal
Authors: Church Michael , Wolcott John , Maizels Judith 
Published: February 2007

AbstractUsing data collected in her field studies, Maizels (1983) compared five methods of calculating palaeovelocity from coarse gravel deposits. Her paper indicated that the five methods provide estimates which differ by up to 2 x. There are several errors in the published equations, however. Upon correction, the smallest estimate is within 3% per cent of the largest. Other published data sets suggest that the distinction among a variety of palaeovelocity equations is not worth pursuing in light of the amount of scatter in typical data. This paper recommends use of the Thompson and Campbell (1979) modification of the basic Keulegan flow resistance equation because it fits the data as well as any other, whilst covering a more comprehensive range of flow conditions. Problems of appropriate roughness length and entrainmnet function remain.
Observations of desert flood bores
Authors: Hassan Marwan A. 
Published: February 2007

AbstractFlood bores have been measured in desert stream floods. The bores were steep and small pebbles were observed to be pushed ahead. Bore velocity changed downstream and was controlled by local channel geometry. In narrow reaches, the bore advanced at rates twice those of wide reaches. Mean bore velocity was about 50 per cent of that of mean flow at peak flood discharge. The surfaces of shallow bores were covered by air foams. This was not the case in deeper, faster examples.
Flood dynamics of a concrete‐lined, urban stream in Kansas City, Missouri
Authors: Vaughn D. M. 
Published: February 2007

AbstractBrush Creek drains a 76·1 km2 watershed within urban Kansas City, Missouri and eastern Kansas. A concrete‐lined reach trending 6·1 km through the Plaza District of Kansas City, Missouri has been the focus for several major floods over the past ten years. Channel geometry, slope, and floodwater elevations were determined in the field for segments of the concrete‐lined section of Brush Creek for a flood event that occurred on September 18, 1986. Discharge was computed by indirect methods and compared to a value determined from a rating curve established by the Water Resources Division of the U.S.G.S. Boundary shear stress, unit stream power, and average velocity were also computed in order to establish a quantitative relationship between sediment distribution, volume, and size fractions; and flow dynamics operating throughout the channel during this event. Boundary shear stress ranged from 91‐96 Nm−2, stream power was 528‐557 Wm−2, while average velocity was 5‐8 ms−1. These values were sufficient to displace concrete slabs as large as 5 m long by 4·6 m wide by 0·23 m thick weighing an estimated 12 245 kg. As the channel was sediment free and unsecured prior to the flood, the distribution of deposits and subsequent channel scour provide valuable evidence for potentially hazardous sections of this urban stream.
The effect of hydrochemical factors on the dissolution rate of gypsiferous rocks in flowing water
Authors: Navas Ana 
Published: February 2007

AbstractIn order to investigate the rate of dissolution of gypsiferous rocks under natural conditions in streams of the Ebro river basin, 55 dissolution trials were carried out with spheres of alabastrine gypsum placed in flowing water. Experimental conditions involved flow velocities between 0·3 and 1·2 m s−1, electrical conductivities between 0·3 and 1·9 dS m−1, and the saturation indices of gypsum between −2·1 and −0·33. Mean values of dissolution rate obtained vary from 104 to 226 gm−2 h−1. This loss of mass corresponded to a volume of gypsum of between 393 and 853mmm−2 year−1. The factors most affecting the dissolution of gypsum are in descending order of importance: flow velocity > electrical conductivity > gypsum saturation.
A study of river channel pattern information recorded by grain size parameters of fluvial sediment
Authors: Jiongxin Xu 
Published: February 2007

AbstractRiver channel pattern may be regarded as the outcome of streamflow, sediment load, and channel boundary conditions, as can the grain size distribution of bed material. It may therefore be expected that connections should exist between river channel pattern characteristics and the corresponding river bed material grain size parameters. Using data from some Chinese rivers, an attempt has been made to express these connections quantitatively by using statistical methods. The work demonstrates that the river's bed load can be related to the percentage of the traction subpopulation of the bed material shown by the probabilistic plot of grain size cumulative‐frequency curve. The study has also revealed some correlations between the bed material grain size parameters of rivers and their channel geometry such as channel width‐depth ratio and channel sinuosity. For instance, the higher the ratio of the traction to suspension subpopulation in bed material, the more sinuous, more shallow, and wider the river channel would be. Furthermore, a discrimination function has been given to distinguish between meandering and wandering braided rivers. If the existence of these relationships can be supported by data from more rivers in other regions, then by using them we can postdict palaeoriver channel geometry and its channel pattern character from fluvial sediment grain size parameters of the palaeoriver. This would open a new way to reconstruct the physicogeographical environment in which palaeorivers developed.