bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some experimental data on slopewash and wind action with reference to quaternary morphogenesis in Belgium
Authors: De Ploey J. 
Published: February 2007

AbstractThis paper discusses field observations, field measurements, field and laboratory experiments concerning the physical weathering and the erodibility of sandy Tertiary rocks and loess mantles in Belgium. The observed phenomena and the experimental data have been discussed in terms of soil mechanics. Special attention has been paid to crack sets and desquamation in consolidated Tertiary sands resulting from lateral offloading, to the relative high erodibility of glauconiferous sands, and to the sensitivity of loess and loamy soils for solifluction, rainwash and colluviation. A stability index E has been proposed for loamy soils based upon the characteristics of the liquid limit curve. Two‐year observations and measurements at the dune station of Kalmthout have shown how the loess fraction can be transported in a basal drift near the ground, and how rainstorms provoke deflation and rainwash on dunes where gravel is moving in saltation during heavy storms. Litter flow has been found to occur on all actual forested slopes. All these data on morphogenetic processes have led to some considerations of the Quaternary morphological evolution of Lower and Middle Belgium: the modelling mainly by sheetwash of periglacial glacis, the evolution of the Hageland hills and of the Plateau of Brabant, the morphodynamics of loamy slopes, Late Glacial and Holocene dune building, and finally the Holocene evolution of forested slopes.
A quantitative rill erosion study on a loamy sand in the hilly region of flanders
Authors: Gabriels D. , Pauwels J. M. , De Boodt M. 
Published: February 2007

AbstractRill and gully erosion was measured for a loamy sand ploughed field. Eight gullies in a 1.4 ha field showed a total loss of 18‐4 T, or 1‐3 mm of denudation for November and December 1974, when 213 mm of rain fell. Soil analysis showed selective removal of fine material, with particles < 50 μ held in suspension until the water infiltrated downslope. During a summer period, 353 mm of rain led to 0.7 mm denudation as sheet erosion from small plots.
Field studies of rainsplash erosion
Authors: Morgan R. P. C. 
Published: February 2007

AbstractStudies on sandy soils of the Cottenham Series in mid‐Bedfordshire confirm in the field the relationships between splash erosion, rainfall energy and ground slope obtained in the laboratory experiments of other workers. Only 0·06 per cent of the rainfall energy contributes to splash erosion and rates are low, attaining a maximum of 0·082 kg m−2 y−1 on a slope of 11°. The major role of splash action is in the detachment of soil particles prior to their removal by overland flow.
The effects of the 1976 drought and autumn rainfall on stream solute levels
Authors: Foster I. D. L. , Walling D. E. 
Published: February 2007

AbstractOperation of a previously existing sampling network during the 1976 drought has provided an opportunity to assess the effects of the drought and subsequent autumn rainfall on the water quality characteristics of a small catchment (9·3 km3) in East Devon. The availability of records for past years has enabled these data to be compared with longer‐term response characteristics.Analysis indicates that the 1976 drought produced a unique solute response, with levels rising markedly during the autumn flush which resulted from the heavy rainfall following the drought period. Concentrations of several ions increased 3–4 times and NO3‐N levels exhibited even greater increases of up to 50‐fold. Some of the factors responsible for these increases and some implications are considered.
Ground movement at runswick bay, North Yorkshire
Authors: Rozier I. T. , Reeves M. J. 
Published: February 2007

AbstractRecent ground movements, varying in importance from superficial slips to large sliding masses, are reported for slopes at Runswick Bay, North Yorkshire. The role of water in controlling both the timing and rate of such movements is stressed. An unexpected consequence of an attempt to limit coastal erosion is reported. Failures are expected to continue.
The determination of erosion rates from exposed tree roots in the piceance basin, colorado
Authors: Carrara Paul E. , Carroll Thomas R. 
Published: February 2007

AbstractTree roots, exposed by hillslope erosion in the Piceance basin of Colorado, were inspected to determine average net erosion rates during the last four centuries. Twenty pinyon pine and juniper root sections were obtained from each of five sites in this region. The date when a root was first exposed by erosion was determined, for 83 of the sections collected, by one of three methods: 1. time of initial cambium dieback; 2. interpretation of annual ring growth pattern; and 3. the earliest occurrence of reaction wood.Analysis indicated no significant difference in erosion rates between the five study sites. However, a strong difference in erosion rates was noted between north‐facing (0–56 mm/yr) and south‐facing (1.18 mm/yr) slopes. No significant difference in erosion rates were found between various south‐facing aspects and local steepness of slopes. Significant differences were noted between erosion rate and the length of time the root was exposed to erosion. Rates of erosion on south‐facing slopes in the pinyon‐juniper community during the last four centuries are as follows: period (years ago) 0‐99 100‐199 200‐299 300‐399 erosion rate (mm/yr) 1‐79 0‐49 0‐33 0‐22.Although there appears to be a slow increase in erosion rates during the three earliest centuries the dramatic increase during the last century may have been substantially augmented by the introduction of cattle into this region approximately one hundred years ago.
Effects of large organic material on channel form and fluvial processes
Authors: Keller Edward A. , Swanson Frederick J. 
Published: February 2007

AbstractStream channel development in forested areas is profoundly influenced by large organic debris (logs, limbs and rootwads greater than 10 cm in diameter) in the channels.In low gradient meandering streams large organic debris enters the channel through bank erosion, mass wasting, blowdown, and collapse of trees due to ice loading. In small streams large organic debris may locally influence channel morphology and sediment transport processes because the stream may not have the competency to redistribute the debris. In larger streams flowing water may move large organic debris, concentrating it into distinct accumulations (debris jams). Organic debris may greatly affect channel form and process by: increasing or decreasing stability of stream banks; influencing development of midchannel bars and short braided reaches; and facilitating, with other favourable circumstances, development of meander cutoffs.In steep gradient mountain streams organic debris may enter the channel by all the processes mentioned for low gradient streams. In addition, considerable debris may also enter the channel by way of debris avalanches or debris torrents. In small to intermediate size mountain streams with steep valley walls and little or no floodplain or flat valley floor, the effects of large organic debris on the fluvial processes and channel form may be very significant. Debris jams may locally accelerate or retard channel bed and bank erosion and/or deposition; create sites for significant sediment storage; and produce a stepped channel profile, herein referred to as ‘organic stepping’, which provides for variable channel morphology and flow conditions.The effect of live or dead trees anchored by rootwads into the stream bank may not only greatly retard bank erosion but also influence channel width and the development of small scour holes along the channel beneath tree roots. Once trees fall into the stream, their influence on the channel form and process may be quite different than when they were defending the banks, and, depending on the size of the debris, size of the stream, and many other factors, their effects range from insignificant to very important.
Semi‐determinate hydraulic geometry of river channels, South Island, New Zealand
Authors: Mosley M. Paul 
Published: February 2007

AbstractData to describe the morphologic, hydrologic and sedimentologic characteristics of 72 South Island, New Zealand, rivers were collected and analysed. Nearly 70 per cent of variation in channel morphology is accounted for by differences in cross‐sectional area, slope, and cross‐section shape; only 53 per cent of the morphologic variability could be statistically ‘explained’ by the hydrologic and sediment variables used. The level of explanation varied for different morphologic variables; nearly 90 per cent of the variability in cross‐sectional area could be explained, but aspect ratio (maximum depth divided by hydraulic radius) was completely independent. Apart from the inadequacy of the measured variables as indices of the true underlying controlling factors, and the imperfect measurement and sampling procedures, the low level of explanation is probably due to the influence of factors such as floodplain vegetation, high quasi‐random variability in bark sediment character, boundary effects imposed by bedrock bluffs, and the precise sequence of flood events, none of which are easily quantified. In addition, observations indicate that there is a large random variation in channel form which cannot be related to any factor.An attempt to relate channel morphology to flow variability, using simple indices of the latter, was unsuccessful.
Rock hardness and landform development in the Gunong Mulu National Park, Sarawak, E. Malaysia
Authors: Day Michael J. 
Published: February 2007

AbstractRock hardness, measured by the Schmidt Test Hammer, is an important factor in explaining some of the sharp contrasts in relief and wide variety of landforms in The Gunong Mulu National Park. It is also useful in consideration of contemporary geomorphological processes, such as landsliding.
Ice‐collapse induced waves and graded gravel ridges on a Lake Beach
Authors: Duck R. W. , McManus J. 
Published: February 2007

AbstractIce collapsing into the waters of proglacial Briksdal Lake, western Norway, generates waves which rework shoreline sediments. Swash establishes graded gravel ridges sub‐perpendicular to the shoreline, derived from material eroded by backwash. A terminal gravel bar at the lakeward limit of wave‐induced transport marks the maximum depth of water surface waves.
Slumping and planar sliding on hill‐slopes in Rwanda
Authors: Moeyersons Jan 
Published: February 2007

AbstractFied observations on Rwaza Hill near Butare (Rwanda) revealed the nearly omnipresence of small natural terracettes, developing as a result of superficial slips and accelerated creep movements. On the steepest slope under study, the humic A‐horizon of the soil profile migrated downslope over a mean distance of 14.5 cm from October 1977 till October 1978.A high hydraulic conductivity horizon, displaying low cohesion and consistency characteristics as compared with overlying and underlying material, is developed at the base of the sliding soil.Planar slides, as well as rotational slips occur, the location of failures being determined by the presence of this plane of weakness.Generation of basal interflow in an artificial soil column showed that the state of failure is preceded by localized rheological creep of a plastic viscous soil material, undergoing seepage pressure.
Dating of post‐glacial landforms in the central howgills
Authors: Harvey A. M. , Oldfield F. , Baron A. F. , Pearson G. W. 
Published: February 2007

AbstractLittle is known of Holocene landform development in Upland Britain. This paper describes a site at Middle Langdale in the Howgill Fells of Cumbria where large, but now stabilized and inactive gullies cut through periglacial material. At the base of the gullies large debris cones have buried earlier alluvial sediments on the valley floor. On these sediments and buried by the debris cones is a well‐developed organic soil from which two 14C dates have been obtained in an attempt to estimate the age range of the soil. These dates range from 2580±55 years BP for the fine particulate fraction from the base of the organic horizon to 940±95 years BP for fossil rootlets from the uppermost organic layer, immediately below the overlying debris cones. The pollen evidence suggests that the valley floor site was initially dominated by alder carr and later by a Juncus marsh with birch, alder and hazel nearby. The pollen, from the surrounding upland area suggests woodland on the valley sides, dominated by oak and elm that was later replaced by a more open environment rich in heath species and in which disturbed ground species were present. The magnetic evidence indicates a stable local environment during soil formation but shows a sudden inwash of unweathered debris at the top of the buried soil.The evidence suggests that the valley floor was geomorphologically stable throughout the period of soil formation, although there was a local change in valley floor vegetation and a reduction of woodland cover on the valley sides at sometime during the period. The evidence then points to major geomorphological changes; a wave of soil erosion, gully development and debris cone deposition, perhaps following the Scandinavian introduction of sheep farming in the tenth century A.D.
Hydrologic and geologic control of carbonate water chemistry in the subarctic nahanni karst, canada
Authors: Brook George A. , Ford Derek C. 
Published: February 2007

AbstractThere are six classes of water and five geologic environments in the subarctic Nahanni karst. During the summers of 1972 and 1973, 214 water samples were collected from 15 of the 30 hydrogeologic categories. Linear discriminant function analysis, using five measured and two derived chemical variables, indicates that there are statistically significant (0.005 level) differences in water chemistry between similar waters in different geologic environments, between waters in the same geologic environment, and between waters in different hydrogeological categories. Geological environment labels a natural water because it determines the availability of soil CO2 and of soluble minerals. Measurements indicate that mean soil log PCO2 is greatest in areas of shale mantled by till (−2.39), and least in areas of sandy fluvioglacial drift (−3.27). Low values on the sandy drift are due to the sparse shrub vegetation, and to the high degree of soil aeration; soils in areas of shale are clay‐rich and support a dense boreal forest. Hydrology influences water chemistry because it determines how much CO2 natural waters pick up from the environment and how much they subsequently lose to the atmosphere, and as a result, whether they dissolve or deposit soluble materials. The similarity between mean calculated log PCO2 in natural waters (−2.92) and mean measured soil log PCO2 (−2.80) suggests that natural waters in Nahanni are dose to equilibrium with mean soil CO2 levels.
The effect of forestry drainage operations on upland sediment yields: A case study
Authors: Robinson M. , Blyth K. 
Published: February 2007

AbstractForestry is generally considered to be a land use giving low sediment yields. However, in Britain most forestry is on land that requires extensive drainage, and it was found that the drainage of a small upland catchment resulted in sediment yields over the following five years equivalent to nearly half a century's load at pre‐drainage rates. Subsequent sediment yields did not decline to pre‐drainage levels, but remained about four times higher, as a result of erosion of the drains.
Toppling failures from alpine cliffs on ben Lomond, Tasmania
Authors: Caine Nel 
Published: February 2007

AbstractLarge cliff failures involving forward toppling over a basal hinge have occurred on more than half of the plateau edge of Ben Lomond, northeastern Tasmania. This mode of failure, which is readily identified from the columnar structure of the dolerite involved, has affected up to 107 m3 of rock at a time and a total of more than 50 × 106 m3 in all the cases which can still be identified. It represents perhaps the most important form of cliff retreat, amounting to a rate of 0.2 mm yr−1 over the last 100,000 years.Topographic evidence and joint surveys suggest that two different mechanisms have produced the topples on Ben Lomond. One has involved failure in the sediments underlying the dolerite with consequent foundering and cambering of large sections of the plateau edge. This mechanism accounts for relatively few of the Ben Lomond topples, though it includes the largest individual cases. The second mechanism, dominant in most of the topples, involved slab failure in the cliffs. Both modes of failure have been facilitated by vertical weaknesses within the bedrock and both require an initially steep cliff profile. Because of the latter requirement, which is not met on the other mountains of northeastern Tasmania, large‐scale topples are found only on Ben Lomond, and only there where glacial steepening of the cliff has been possible. Following the initial failure, topples of both types have migrated downslope by block sliding for distances up to 2 km.
Short term fluctuations in dissolved organic matter concentrations in streamflow draining a forested watershed and their relation to the catchment budget
Authors: Foster I. D. L. , Grieve I. C. 
Published: February 2007

AbstractDissolved organic matter (DOM) concentrations in throughfall, throughflow, and runoff were recorded in a small (95 ha) woodland catchment in North Warwickshire for a period of eight weeks following a prolonged dry spell. DOM is shown to be positively related to stream discharge over the sampling period, although distinctive flushing effects were identified. The net contribution of DOM to total dissolved solids load carried in the river was only 2.4 per cent, and represented significantly less than published carbon losses by mineralization of soil organic matter. Throughfall inputs were some 100 times higher than streamflow outputs from the catchment.
Field measurements of rainfall drop‐size distribution, and the relationships between rainfall parameters and soil movement by rainsplash
Authors: Kneale W. R. 
Published: February 2007

AbstractRainfall drop‐size distributions were measured at a site in northern England using the ‘oflour‐pellet’ technique. A relationship between intensity and kinetic energy is presented. Even at the low rainfall intensities observed (< 5 mm h−1 average over an hour) measureable amounts of rainsplash movement took place, and these movements have been related to rainfall parameters.
Evaporite dissolution and development of karst features on the rolling plains of the texas panhandle
Authors: Gustavson Thomas C. , Smpkins William W. , Alhades Alan , Hoadley Ann 
Published: February 2007

AbstractMore than 400 dolines, consisting of collapse sinkholes and closed depressions, occur in Hall and Briscoe Counties, Texas. Of these, at least 36 sinkholes and two depressions formed between 1940 and 1972. Collapse sinks are typically circular and range up to 100 m in diameter and 15 m in depth. Closed depressions are irregularly‐shaped, internally‐drained depressions up to 2.4 km in length. Surface fractures up to 1.5 km in length are associated with certain closed depressions.Karst features are forming as a result of intrastratal dissolution of Upper Permian evaporites, primarily halite and secondarily gypsum. Salt dissolution and overburden collapse are evident from geophysical log cross‐sections and occur at depths ranging from 195 to 275 m. Dissolution is progressing down dip and mean dissolution rates for salt beds in the Hall County area range from 0.29 to 7.73 cm/yr.The valley of the Prairie Dog Town Fork of the Red River is an area of ground‐water discharge for flow systems moving eastward from topographically high areas of the Rolling Plains and from the eastern rim of the High Plains. Halite beds in contact with these waters undergo dissolution. Salt springs and brine seeps, some associated with sinkholes and depressions, occur in the discharge area and indicate that dissolution is an ongoing process.
Test of scale modelling of sediment transport in steady unidirectional flow
Authors: Southard John B. , Boguchwal Lawrence A. , Romea Richard D. 
Published: February 2007

AbstractIn two steady uniform flows at different physical scales in a small open channel, with variables characterizing flow, sediment, and fluid adjusted for dynamic similitude by means of four dimensionless modelling parameters (a Reynolds number, a Froude number, a density ratio, and a length ratio), measured frequency distributions of height, spacing, and migration rate of current ripples were almost identical when scaled, thus verifying that exact Reynolds‐Froude modelling of loose‐sediment transport is valid and workable. Modelling should be valid as well for a wide range of other transport conditions in the same kind of flow, because no additional kinds of forces or effects would be present in transport of loose grains in modes other than as ripples. In scaled‐down modelling, a scale ratio of 2.5 is attainable without recourse to exotic fluids by use of water at 85°C to model natural flows at 10°C.
A simulation study of the development of rillenkarren
Authors: Glew J. R. , Ford D. C. 
Published: February 2007

AbstractRillenkarren are patterns of tightly packed, small solution rills found upon bare, sloping surfaces of soluble rocks in all climates. They head at the crest of a slope and are replaced downslope by a planar solution surface, the ausgleichfläche. Development has been simulated successfully using a rainfall simulator and plaster of paris blocks. Ten principal experiments were completed with blocks at inclinations ranging 22½–60°, temperature and rainfall intensity being constant. Results suggest that rillenkarren develop within a hydrodynamic zone of rim effect where the depth of threads or sheets of runoff is insufficient to prevent direct raindrop impact upon the underlying soluble solid. Where depth of runoff becomes sufficient rills are replaced by the ausgleichfläche. Between upper and lower limits, rill length is proportional to slope in a log linear manner. Rill cross‐sections approximate the parabola, the most effective shape for focussing raindrop erosion in the axis of the trough: this explains the tight packing characteristic. Ausgleichfläche and rill troughs evolve by parallel retreat at the original slope angle, the erosion rate being greatest at about 45°.
Longshore variations in nearshore wave processes at magilligan point, northern ireland
Authors: Carter R. W. G. 
Published: February 2007

AbstractMagilligan Point is a recurved cuspate foreland at the mouth of Lough Foyle. Two wave regimes intersect in the estuary mouth and the manner of their interplay controls shoreline changes. Ocean swell waves from the N and NE are refracted around the recurve, losing both height and energy longshore. Width of the surf zone decreases and waves tend to steepen, although both these changes and wave refraction owe something to nearshore geometry. Angle of wave approach becomes more acute and a westerly flowing longshore current moves sand S and SW along the beach. Estuary waves from the S and SW are wind‐driven with high‐frequencies and steepnesses. They generate a northeasterly current which returns material N, but dies out as the waves become obliterated by nearshore attenuation and breaking of swell. It is possible to identify a time‐averaged null‐point where shoreline wave power is balanced, although this tends to shift over short periods causing rapid morphological changes. The existence of two independent, but counteractive cells ensures the long‐term maintenance of the foreland, without requiring major or continuous supplies of fresh sediment.