bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined Two‐Stage Xanthate Processes for the Treatment of Copper‐Containing Wastewater
Authors: Chang Y. K. , Leu M. H. , Chang J. E. , Lin T. F. , Chiang L. C. , Shih P. H. , Chen T. C.
Published: February 2007

Heavy metal removal is mainly conducted by adjusting the wastewater pH to form metal hydroxide precipitates. However, in recent years, the xanthate process with a high metal removal efficiency, attracted attention due to its use of sorption/desorption of heavy metals from aqueous solutions. In this study, two kinds of agricultural xanthates, insoluble peanut‐shell xanthate (IPX) and insoluble starch xanthate (ISX), were used as sorbents to treat the copper‐containing wastewater (Cu concentration from 50 to 1,000 mg/L). The experimental results showed that the maximum Cu removal efficiency by IPX was 93.5 % in the case of high Cu concentrations, whereby 81.1 % of copper could rapidly be removed within one minute. Moreover, copper‐containing wastewater could also be treated by ISX over a wide range (50 to 1,000 mg/L) to a level that meets the Taiwan EPA's effluent regulations (3 mg/L) within 20 minutes. Whereas IPX had a maximum binding capacity for copper of 185 mg/g IPX, the capacity for ISX was 120 mg/g ISX. IPX is cheaper than ISX, and has the benefits of a rapid reaction and a high copper binding capacity, however, it exhibits a lower copper removal efficiency. A sequential IPX and ISX treatment (i.e., two‐stage xanthate processes) could therefore be an excellent alternative. The results obtained using the two‐stage xanthate process revealed an effective copper treatment. The effluent (Ce) was below 0.6 mg/L, compared to the influent (C0) of 1,001 mg/L at pH = 4 and a dilution rate of 0.6 h–1. Furthermore, the Cu‐ISX complex formed could meet the Taiwan TCLP regulations, and be classified as non‐hazardous waste. The xanthatilization of agricultural wastes offers a comprehensive strategy for solving both agricultural waste disposal and metal‐containing wastewater treatment problems.
Progressive changes in the morphology of fluvial terraces and scarps along the Rappahannock River, Virginia
Authors: Colman Steven M.
Published: February 2007

Progressive geomorphic changes in the flight of fluvial terraces along the Rappahannock River, Virginia, provide a framework for analysing the effect of time on landforms. The oldest terrace is probably no younger than early Quaternary, and the youngest major fill terrace probably correlates with the high sea level of the last major interglacial. A uranium‐series date of 187,000 yr has been obtained on coral from marine sediments related to this terrace.

Indices of terrace preservation, especially drainage densities and area to perimeter ratios, show systematic changes with terrace age. Hence, these variables appear to satisfactorily indicate relative age, and could perhaps be used to estimate actual ages if suitably calibrated.

The morphology of scarps formed by entrenchment of the fluvial terraces is more variable than analogous morphology of fault scarps and wave‐cut bluffs. However, measurements of the fluvial scarps clearly indicate that for a given terrace age, higher scarps tend to have steeper slopes, and that for a given scarp height, older scarps tend to have gentler slopes.

The terrace forms themselves are preserved for at least several million years. Depositional features such as bars and channels with l–3m of relief are preserved on terraces on the order of 105 yr old. Scarps related to the formation of terraces of this age are well preserved and have slopes of about 6–8 degrees where the scarp height is about 5 m. The preservation of fluvial landforms and scarps suggests that, if fault scarps comparable to these features were commonly formed by earthquakes in low relief areas of the eastern United States, many should be recognizable.
Contributions to storm quickflow in a small headwater catchment—the role of natural pipes and soil macropores
Authors: McCaig Michael
Published: February 2007

Analysis of hydrographs from a 4·3 hectare stream head catchment indicates that storm runoff is generated from dynamic source areas. The volume and timing of contributions from different parts of the catchment show, when compared with the extent of surface saturation, that pipeflow generated from areas not saturated at the soil surface is a significant component of the quickflow hydrograph. A simple model of pipeflow generation and contribution is discussed in the light of field results.
Dune formation on the humid tropical sector of the North Queensland Coast, Australia
Authors: Pye K.
Published: February 2007

Several previous attempts have been made to explain the apparent poor development of coastal dunes in the humid tropics in terms of lack of wind energy, failure of sand supply to the shoreline, excessive climatic wetness, salt crust formation on beaches, and the character of tropical back‐beach vegetation. However, recent published reports indicate that coastal dune occurrences are more common in the humid tropics than was formerly thought, throwing suspicion on the idea that environmental conditions militate against dune formation in these areas as a whole. Evidence from the humid tropical sector of the North Queensland coast suggests that the poor development of dunes in this area primarily reflects poor sediment sorting in the beach and nearshore zone and low wind energy at the shoreline due to the nature of the coastal orientation and physiography in relation to the prevailing southeasterly winds. These limiting factors are not unique to humid tropical climates.
Cavernous weathering in the Capitol Reef Desert, Utah
Authors: Mustoe G. E.
Published: February 2007

Tafoni and honeycomb weathering are abundant in sandstones at Capitol Reef National Park. Cavities are particularly common in talus blocks resting on alkali‐rich soil, in vertical walls of desert washes, and in sandstones containing calcareous cement. Chemical analyses, X‐ray diffraction data, and field observations suggest that salt weathering is the most important cause of disintegration, but dissolution of calcite cement also occurs in calcareous sandstones. Cavernous weathering at Capitol Reef produces cavities similar in appearance to features found in arkose outcrops along the coast of northwest Washington, even though the environmental conditions at these two locations are very different.
Equilibrium bank geometry and the width of shallow sandbed streams
Authors: Pizzuto James E.
Published: February 2007

Cross‐sections of 16 straight sandbed streams in Minnesota, Iowa, and Nebraska were surveyed. Two stratigraphic horizons were found in the banks at each site, an upper cohesive unit usually composed of silt and clay and a lower unit composed of sand.

Bank erosion on these rivers occurs when the upper cohesive unit is undercut by scour at bends. The overhanging cohesive block fails by beam or cantilever failure. As upper bank failure is a direct result of undercutting, the stability and rate of retreat of the bank are largely determined by erosion of the sandy part of the bank. The cohesive layer has little influence on bank retreat and width adjustment on the rivers studied here.

A quantitative lateral sediment transport model developed by Parker (1978a) is used to calculate the steady‐state geometry of the sandy part of the bank. Results are obtained for the shape, length, and height of the sandy part of the bank. The model predicts the length of the bank fairly well, and the theoretical equation for the height of the bank is of the correct form. The model, however, overestimates the slope of the bank.

The height of the sandy part of the bank (Db) is approximately equal to the depth of the mean annual flow. Since Db is determined by the lateral sediment transport model, the width (W) may be obtained from the equation of continuity (Q = WDbV), published flow (Q) data, and a resistance equation for the mean velocity, V. The calculated widths are similar to those measured in the field.
Characteristics and occurrence of wind erosion features in the Namib Desert
Authors: Lancaster N.
Published: February 2007

Small scale features resulting from wind erosion are widespread in the Namib Desert. They include selective erosion of lithological variations (etching), flutes and grooves, facetting of clasts and residual boulders, and smoothing and polishing of rock surfaces. Large scale features are tentatively identified and are restricted to the southern Namib, with its high energy, unidirectional wind regime.

Wind erosion features are best developed on fine‐grained rocks of intermediate hardness. They are oriented towards or parallel to modern strong winds.

The turbulent flow of wind armed only with dust particles is probably more important than wind driven sand in creating smooth polished rock surfaces, flutes, and grooves. Wind driven sand appears to be significant only in facetting rock masses.
The identification of four stages during micro‐rill development
Authors: Merritt Elaine
Published: February 2007

Separation of rill and inter‐rill erosion is required in many of the soil erosion models currently being developed. The feasibility of basing the separation on the hydraulic properties of the flow and resultant sediment production is examined in a laboratory simulation of rill initiation and development. Four stages are identified in the process of rill formation; these are sheetflow, flowline development, micro‐rills, and micro‐rills with headcuts. There are significant differences in terms of flow characteristics between the stages, especially between sheetflow and flowlines, indicating the promise of this method for making a more precise distinction between rill and inter‐rill erosion.
Holderness coast erosion and the significance of ords
Authors: Pringle (Nee Phillips) Ada W.
Published: February 2007

A sample ord, a low section of beach characteristic of the Holderness coast, is examined as it moved southwards between 1977 and 1983 and its significant role in coast erosion is demonstrated. The reduction in beach level at the cliff foot by up to 3.9 m enabled most HWN tides to reach it, as compared with only some HWS tides along the inter‐ord beach, and the volume of till eroded from the cliffs increased by eight times to an annual mean of 72m3m−1. The Holderness tills are shown to be composed of 31 per cent sand and coarser sediment which is the sediment range of the beaches. Where an ord is sited the massive injection of beach sediment goes to form the ord's most prominent constructional feature, the lower beach ridge which extends southwards from the centre of the ord. Analysis of 12 months' observer wave data collected at Withernsea in 1969/70 indicates that a net southward sand movement of 144 000 m3 occurred. Comparison of this rate with beach sediment input rates along the whole coast backed by till cliffs suggests a sediment deficit at the northern end and a surplus towards the southern end. This conclusion is supported by an overall increase in beach sediment volume southwards from Barmston. Within this longshore sediment transport system, the ords migrate southwards from their point of origin in the Barmston‐Skipsea area, without losing their identity until reaching the tip of Spurn Head.
Traditional and multivariate techniques in the interpretation of floodplain sediment grain size variations
Authors: Brown A. G.
Published: February 2007

The vertical and horizontal variation of sedimentary fades is the raw data for the interpretation of flood plain history from which palaeohydrological inferences are frequently drawn. Mixed and fine floodplain sediments present problems of interpretation because of a large grain size range and frequent polymodality caused by the mixing of process‐associated grain size components. This paper discusses the use of traditional grain size statistics and the use of the mode and multivariate statistics. The mode, although much neglected, is indicative of up‐profile grain size changes and has practical advantages over the mean for mixed and fine floodplain sediments. Constrained cluster analysis and principal components analysis are used directly on Coulter counter results. These techniques can rapidly divide a floodplain profile into grain size units and indicate the principal vectors of grain size variation which will be related to the changing processes of deposition. Principal components analysis reveals the importance of the medium to fine silt category in accounting for grain size variations, suggesting that a critical factor in determining the type of alluvial unit deposited is the degree to which it has received fine suspended material. Grain size data from the Lower Severn are used to construct a CM diagram which is compared with a texture triangle. From both the CM and multivariate analysis a generalized backswamp profile is constructed which shows the existence of a coarser top unit caused by the addition of a fine to medium sand component to the underlying sediment during the Late Holocene.
Winds and sand movements in the Namib Sand Sea
Authors: Lancaster N.
Published: February 2007

Wind regimes in the vicinity of the Namib Sand Sea are high energy unimodal near the coast, becoming bimodal or complex inland. There is an overall decrease in wind energy and sand transport rates from south to north and west to east, such that sand moves from coastal and southern source areas to accumulate in the northern and central parts of the sand sea. Such a pattern can explain much of the observed spatial variability in dune types, sizes, and sediment characteristics and lends support to a climatic model of sand sea formation in this region.

Seasonal and daily cycles of wind velocity and direction give rise to episodic sand transport, most of which is generated by winds of moderate velocity and frequency.
Approaches to dynamic equilibrium in theoretical simulations of slope development
Authors: Ahnert Frank
Published: February 2007

The model SLOP3D is used to identify characteristic aspects of slope development under different conditions. A series of slopes along the Kall valley in the northern Eifel is reproduced by a developmental sequence of model slopes. The spatial and temporal variations of the components of slope development systems (relief, slope form, weathering rates, denudation rates) are discussed by means of mass movement and wash denudation models. The negative feedbacks between system components create a tendency towards the establishment of a dynamic equilibrium which is reached, however, only if the endogenic and exogenic conditions remain constant for the required relaxation time. The latter is shown to be a function of slope length, of the rate of uplift, of the denudational process type, and of the intensity of exogenic inputs (e.g. precipitation). Varying rock resistance leads to the development of shield inselbergs only if the rate of denudation becomes higher than the maximum possible weathering rate of the resistant bedrock.
Slopes, boundary conditions, and the development of convexo‐concave forms—some numerical experiments
Authors: Armstrong Adrian C.
Published: February 2007

Slope profile sequences are as much influenced by their boundary conditions as they are by the processes operating. The development of a simple slope under a single process can adopt a variety of forms depending on initial and boundary conditions, and a given form can be derived from several different processes. For example, convexo‐concave forms develop under soil creep with basal accumulation, under wash with an initial step form, and under mixed wash and creep processes.
Accuracy and precision of methods for estimating river loads
Authors: Ferguson R. I.
Published: February 2007

River loads often have to be estimated from continuous discharge data but relatively infrequent sampling of sediment, solute, or pollutant concentrations. Two standard ways of doing this are to multiply mean concentration by mean discharge, and to use a rating curve to predict unmeasured concentrations. Both methods are known from previous empirical studies to underestimate true load. Statistical considerations explain these biases and yield correction factors which can be used to obtain unbiased estimates of load. Simulation experiments with normally‐distributed scatter about log‐linear trends, and sampling experiments using a natural data set, show that the corrected rating curve method has lower sampling variability than other unbiased methods based on average instantaneous load and is thus the recommended procedure when the rating plot is of the assumed form. The precision of all methods increases with sample size and decreases with increasing rating‐curve slope and scatter.
The effects of soil piping on contributing areas and erosion patterns
Authors: Jones J. A. A.
Published: February 2007

Natural piping doubles the dynamic contributing area on the upper Maesnant stream in mid‐Wales, mainly through linking points well beyond the riparian zones of seepage to the stream. Both discharge and sediment transport rates in the major pipes are closely related to the size of shallow surface microtopographic hollows in which they lie, and which themselves are largely created by piping erosion. However, pipe dischrges are frequently generated by contributing areas larger than these surface depressions and some pipes run counter to the surface topography. The redistribution and acceleration of hillslope drainage processes by piping has implications for theories of hillslope development, especially through plan‐form modifications, and also for channel discharge and erosion.
Holocene alluvial fan and terrace formation in the Bowland Fells, Northwest England
Authors: Harvey A. M. , Renwick W. H.
Published: February 2007

In the Bowland Fells, Lancashire, northwest England, in the headwater valleys of the Hodder river system, is a suite of Holocene fluvial landforms. Debris cones and alluvial fans at tributary junctions, and river terraces along the main valleys post‐date late Pleistocene forms and pre‐date the modern valley floor alluvial forms. Eight 14C dates from wood samples incorporated within the terrace and fan deposits have allowed two main phases of Holocene erosion to be identified with debris cone/fan deposition taking place after c. 5400 BP but before c. 1900 BP and again at c. 900 BP. Some of the fans and cones are complex with deposits attributable to both phases; others are simple and attributable only to the later phase. In the headwaters an upper terrace at c. 5400 BP pre‐dates the cones and a lower terrace is contemporaneous with the first debris cone phase. Lower downvalley the youngest of three terraces date from c. 5000 BP or earlier indicating that the sequence is less complex downstream.
Manganese‐rich rock coatings from Iceland
Authors: Douglas G. R.
Published: February 2007

Manganese‐rich rock coatings are widespread in Iceland, especially in fractures in basalt lavas. Three common types of coating are described. A thick subsurface coating is found on whaleback forms on high plateaux. The most common type is thinner and occurs in hydrothermal clay‐filled fracture systems which are especially well developed in tholeiite lavas. A third type occurs in younger rocks and is associated with tephra‐rich, loessic sediment which fills open fractures and vesicles. There are differences in the chemistry, morphology, and mineralogy of these coatings which are interpreted as being due to the different microenvironments in which they form. The fracture microenvironment is regarded as being of much more importance to coating thickness and chemistry than simple age and in this respect the hydrothermal clays seem to favour rapid manganese concentration. On the other hand, there are variations in coating type, both laterally and vertically through the lava succession, which are related to regional distribution of hydrothermal alteration and rock type. The regional patterns are the result of Iceland's lateral drift and as a result there is an incidental connection between coating type and rock age. There is some evidence to suggest that the manganese coatings may be both forming and being degraded rapidly in the present environment.
Blue‐green algae and terrestrial limestone weathering on Aldabra Atoll: An S.E.M. and light microscope study
Authors: Viles H. A.
Published: February 2007

Blue‐green algae have been observed to affect limestone weathering on Aldabra Atoll, Indian Ocean. Three different habitats can be identified on the rock surface, i.e. epilithic, chasmolithic, and endolithic. Algae in each habitat may affect weathering in various ways. Samples of blue‐green algae and rock were taken from various terrestrial and coastal environments on Aldabra Atoll. Samples of limestone tablets and calcite crystals after one year in situ were also studied. Light and S.E.M. microscopy revealed that endolithic boreholes were present on many samples, especially those from frequently wetted sites, to a maximum depth of 800 μm. An ‘altered zone’ of micrite and algal filaments was also discovered in many samples. From morphological and petrographical evidence blue‐green algal influences on weathering on Aldabra Atoll seem to be very complex and cannot easily be related to small scale landforms.
Sampling for isotopic responses in surface waters
Authors: Lawler H. A.
Published: February 2007

This paper considers situations in which stable isotopes may be used as natural tracers of precipitation through to surface waters. Two aspects affecting the applicability of the technique are highlighted: first, the variance through time of isotope concentrations in precipitation, i.e. the isotope input signal, and second, the attenuation or damping of this signal during the transmission of water downwards through the hydrological system. Both factors affect the likelihood of obtaining an isotope response, i.e. a variation of isotope concentrations in a surface water which may be related to variations in the precipitation input.

Analysis of precipitation over the Malham area, U.K., reveals large isotopic variations through time. These variations, however, are only poorly correlated with meteorological variables (temperature, precipitation amount, and air mass type). Snowmelt and occluded frontal rainfall are suggested as providing the most reliable ‘spikes’ for an isotopic response at the output in tracing studies. In most hydrological systems, a high degree of signal attenuation is noted. In the Malham area of karst, 57 per cent of the total range of input variation was lost in surface waters, whilst 74 per cent was lost in mobile soil moisture. An isotopic response can only reasonably be expected in a system with rapid throughput, where there is little opportunity for mixing and storage of waters.
Soil pipes and their role in runoff generation and chemical denudation in a humid tropical catchment in dominica
Authors: Walsh R. P. D. , Howells K. A.
Published: February 2007

Numerous soil pipes are reported from a small catchment in an area of kandoid (kaolin‐rich) soils and 2375 mm annual rainfall in the humid tropical volcanic island of Dominica, West Indies. Two spot surveys in August 1982 at baseflow during the wet season indicated that pipes contributed at least 14–16 per cent of streamflow. Sampled pipeflow was of similar chemical composition to the baseflow‐dominated streamwater. Specific conductance (249–420 μS cm−1) and silica (75 mg l−1) levels of pipeflow were high and suggested that the pipes tapped solute‐rich water close to the soil‐rock interface. The principal pipes flow perennially and showed little response to daily rainfalls of up to 43 mm during the monitoring period.
Incipient motion conditions for single rock fragments in simulated rill flow
Authors: Torri D. , Poesen J.
Published: February 2007

Laboratory experiments using simulated tilting rill channels with different bed roughnesses have been conducted to determine hydraulic conditions for incipient motion of single rock fragments lying on rill beds. These threshold conditions can be described by a modified Shields' entrainment parameter (θm) and relative depth (Z), adjusted for rill conditions. The negative relation found between θm and Z also fits steep (stream) channel data collected by other investigators. Plots of the classical Shields' entrainment parameter (θ) versus both relative depth and relative particle size also showed clear negative trends. Special care has been taken to avoid false relations that can arise between compound parameters. This occurs when the latter are not independent from each other because of their definitions.
On the modelling of sand bedforms using the semivariogram
Authors: Robert André , Richards Keith S.
Published: February 2007

This study shows the usefulness of the semivariogram for modelling sand ripples created by water flows of varied flow intensity. A combination of two mathematical functions is fitted to each sample semivariogram, that is an exponential (or stochastic) component and a periodic component. The parameters of each of these components have direct physical meaning. A non‐dimensional ratio combining the two parameters of the exponential model is interpreted as a regularity index (which increases with the degree of regularity of bedform arrangement). This regularity index is inversely related to the Froude number of the flow. The non‐dimensional wavelength, estimated from the dominant periodic function, is also inversely and closely related to the Froude number. The wave height, accurately estimated from properties of the two fitted components, is a direct function of flow velocity and is also proportional to the standard deviation of bed elevations. The bedform shape introduces a considerable discrepancy between the generally assumed normal frequency distribution and the empirical distributions of bed height. The series of bed elevations are generally characterized by a mixture of normal distributions having the same variance but different means. The calculation of a covariance assuming a constant and single mean (as in spectral analysis) can therefore be misleading and the problem may be avoided by using the semivariogram.
Neoglacial gelifluction in the Jostedalsbreen Region, Western Norway: Evidence from dated buried palaeopodsols
Authors: Nesje Atle , Kvamme Mons , Rye Noralf
Published: February 2007

Radiocarbon dating of thin palaeopodsols buried beneath turf‐banked gelifluction lobes at four localities in the low alpine mountain zone in the Jostedalsbreen region, western Norway, show that gelifluction processes were initiated subsequent to the late Subboreal Chronozone. Although large age‐depth gradients have been demonstrated from buried palaeosols in southern Norway, evidence is presented that the palaeosols in this study show only moderate age‐depth gradients. The age estimates from these buried palaeosols give maximum dates of burial, but the error is not thought to be large. Gelifluction processes were probably initiated close to the time of the climatic deterioration, which led to the formation of the present glaciers during the Subatlantic Chronozone. The processes may have been most active during the peak of the Little Ice Age, during which a periglacial climate was established to low levels in this mountainous region.
Flood and vortex scour of the channel bed of the Prosna river, and their depth range
Authors: Młynarczyk Zygmunt , Rotnicki Karol
Published: February 2007

Flood and vortex scour were observed in the Prosna channel (Central Poland) in the years 1980–1985. Flood scour increases the thickness of the reworked channel deposits by 30 per cent to 66 per cent, in relation to the thickness determined by the elevation of the normal bed and the bankfull stage. Vortex scour can increase the thickness by as much as 90–95 per cent. Knowledge of these properties of contemporary alluvium allows correct palaeohydrological and stratigraphic interpretation of the alluvial fills of valley floors.
Rates and patterns of bedrock denudation by coastal salt spray weathering: A seven‐year record
Authors: Mottershead D. N.
Published: February 2007

Rapid surface lowering of bedrock is taking place in the supratidal zone by salt spray weathering. A seven‐year run of data demonstrates a mean rate of lowering of 0·625 mm a−1. Considerable variation exists in annual point lowering values within measurement sites, although between‐site variation is not significant. Aggregate year to year variations in surface lowering are not significant. Spatial variation in individual point values may be compensated by temporal variation over an 11‐year period. There is a marked summer maximum in surface lowering rate, and this is strongly correlated with monthly air temperature. Spatially and temporally episodic swelling of the rock surface is demonstrated. This does not correlate statistically with any available climatic variable and is deemed to be a real and largely stochastic phenomenon. It is interpreted as rock bursting at the granular scale due to haloclasty. The processes most likely to be responsible for the observed rapid denudation are crystallization and thermal expansion of halite, both of which are enhanced by high summer temperatures.
Stemflow and throughfall in a tropical dry forest
Authors: Kellman Martin , Roulet Nigel
Published: February 2007

The rainfall received by a small plot of tropical deciduous forest on sand dunes in Veracruz, Mexico, was partitioned into stemflow and throughfall components to determine whether funnelling by stemflow could reduce soil leaching by transmitting large volumes of water through vertical soil pathways beneath each stem. Although soil infiltration capacities were high, only a very small proportion of incoming rainfall was funnelled by canopy stems. This is attributed to the widely‐branched morphology of mature trees. Smaller trees and shrubs were more effective funnellers of rainfall, and a crude estimate of the magnitude of stemflow in the understorey stratum in one rain event suggested a contribution approximately ten times that of canopy stemflow. However, even if augmented by the understorey stratum in this way, total stemflow is unlikely to have exceeded 10 per cent of gross precipitation, implying that it does not represent an important leaching‐avoidance mechanism in this forest.
Blanket peat erosion in a mid‐wales catchment during two drought years
Authors: Francis I. S.
Published: February 2007

The rate of blanket peat erosion was measured at an upland site in central Wales during the 1983‐1984 drought years. Erosion pins, a peat surface sediment trap, and sediment sampling in the effluent stream, were used to estimate the rate of peat surface recession and the rate of organic sediment loss from the catchment. An overall rate of surface recession of 16 mm y−1 on exposed peat faces was recorded; this differed between faces of different aspects, with the greatest recession on southwest faces. Eroding peat surfaces exhibited maximum recession during the summer, but the peat surface sediment trap indicated that the highest rates of sediment loss from peat faces due to rain wash occurred during the autumn and early winter. Stream sediment sampling showed that the yield of organic sediment from the catchment was 34·4 t km−2 yr−1, with greatest losses also during the autumn and early winter. The evidence suggested that the surface recession, as measured on erosion pins, included a ‘wastage’ or shrinkage component, which possibly accounted for as much as 80 per cent of the apparent loss. Direct and circumstantial evidence suggested that peat wastage during the summer months was the most important agent of surface recession in the study period, which encompassed the two dry summers. Desiccation provided available sediment during the autumn, but organic sediment supply became limited as the winter progressed, despite the occurrence of frost heave.
The weathering effects of the lichen Lecidea aff. Sarcogynoides (Koerb.) on magaliesberg quartzite
Authors: Cooks J. , Otto E.
Published: February 2007

The effect of the weathering processes generated by Lecidea aff. Sarcogynoides (Koerb.) on the substrate was studied by means of a scanning electron microscope. The elements present in the substrate (Magaliesberg quartzite) and in the lichen thallus were determined by X‐ray fluorescence spectrometry for the purpose of comparison. The elements present were mostly similar although a few were present in the thallus which were not observed in the quartzite. It is possible that those elements present in the lichen thallus which were not present in the substrate may have been extracted from the atmosphere. The occurrence of small hollows (weathering pits) in which the early stages of plant development occurs, and the disintegration of the rock indicate that Lecidea aff. sarcogynoides (Koerb.) contributes to the chemical weathering processes by chelation and mechanically by the penetration and expansion of hyphae. A model is proposed in which a possible mechanism for these weathering processes is suggested.
Velocity‐discharge relationships in three lowland rivers
Authors: Knighton A. D. , Cryer R.
Published: February 2007

The use of different functional forms to describe the variation of velocity with discharge is explored for four cross‐sections, nine short reaches (100‐250 m), and three long reaches (2‐7 km) in three lowland rivers in Lincolnshire. The traditional log‐linear relationship applies to more than half the cases, the degree of correlation never falling below 0‐9. Although probably more valid from a physical standpoint, the log‐quadratic relationship‐is only moderately successful, one problem being the position of the vertex relative to bankfull discharge. Alternative formulations based on a kinematic routing model and a partitioned log‐linear model have restricted application. Rates of change of velocity with discharge are relatively high in these lowland rivers, not only at‐a‐station but also downstream. One explanation is that velocity becomes particularly sensitive to local slope and within‐channel vegetation conditions as discharge decreases, resulting in rather low velocities at small discharges.

Cross‐sectional and reach‐based results are compared for neighbouring stretches of river. Velocities in short reaches do not differ appreciably from those at nearby cross‐sections or from those in long reaches with a length of less than 3 km. By integrating within‐reach variability and avoiding the need to chose a representative cross‐section, velocity measurement over short reaches is probably preferable to that at cross‐sections as a basis for at‐a‐station hydraulic geometry.
Effects of vegetation on soil slippage by pore pressure modification
Authors: Terwilliger Valery J.
Published: February 2007

Influences of vegetation on shallow (< 1 m) soil slip formation through modification of soil water was investigated on hillsides covered by verdant chaparral (dense shrubland), and burned vegetation in the Transverse Ranges of California. Per cent available water and hydraulic potentials were obtained from electrical resistance blocks and tensiometers for one year in soils under burned and unburned vegetation on three slopes. Soil remained moister during a dry period under burned vegetation than under unburned chaparral on two of the three slopes studied. Daily increases in per cent available water and hydraulic potential of soils were greatest for a given storm where soil was driest prior to the storm. Furthermore, water levels in soil tended to be greatest for a given storm where soil water levels had been lowest prior to the storm. These two findings were corroborated by laboratory wetting trials on undisturbed soils of vastly differing mechanical properties in that initially drier soils always absorbed water faster and became wetter than initially moister soils. In the field, soil water levels became similarly high under all vegetation after several storms and varied little throughout the remainder of the wet season. These results contradict the common assumption that depletion of soil water by vegetation would result in slower saturation rates and hence greater resistance of a soil mass to slippage.
Developments in a non‐destructive method of determining rock strength
Authors: Allison Robert J.
Published: February 2007

Material strength is an important variable for any study of the relationships between rock mass geomechanical characteristics and landform development. Standard field and laboratory tests for measuring strength present a variety of problems to the geomorphologist. Recent studies (Allison, 1988) have described a laboratory based non‐destructive method for indirectly determining material strength, by measuring Dynamic Young's Modulus. Data presented here suggest that the same apparatus can be used as a field technique. Tests have been conducted on the Devonian limestone of the Napier Range, Western Australia. Laboratory results obtained using the non‐destructive ultrasonic apparatus have a high correlation with triaxial Hoek Cell tests. Results from on‐site tests have much greater accuracy than data collected using the Schmidt hammer, which is currently the most widely used geomorphological field technique for determining rock strength.
Topography and ice sheet growth
Authors: Payne Antony , Sugden David
Published: February 2007

This paper uses a numerical ice sheet model to investigate the role of topography in influencing ice sheet growth. The model is applied to the maritime, mid‐latitude uplands of Scotland and relies on a series of assumptions about mass balance, topography, and ice flow. It is driven by an imposed pattern of temperature change. The model is able to predict effectively the extent and thickness of the Loch Lomond ice sheet, using a palaeotemperature curve based on Coleoptera assemblages.

A series of experiments with a stepped, constant July air temperature depression suggests that in Scotland a change in excess of −3·0°C is necessary to initiate ice sheet growth; that steady state ice caps build up at changes of −3 to − 6·5°C; and that large ice sheets build up at changes of more than − 6·625°C. The bifurcation revealed by the last two types of behaviour is the result of topography. Both the vertical amplitude and the spatial distribution of bedrock basins and ridges are important in determining the pattern, rate, and extent of ice sheet growth. The implication is that topography plays an important role in determining the dynamics of ice sheet growth.
Differential weathering of feldspar and pyroxene in an arctic‐alpine environment
Authors: McCarroll Danny
Published: February 2007

The relative relief of adjacent plagioclase and pyroxene minerals was accurately measured on a recently‐exhumed outcrop of gabbroic rocks in Leirdalen, southern Norway. Above the level of the former soil surface the feldspars protrude above the pyroxenes whereas below that level the pyroxenes are higher. Differential relief declines with increasing depth of burial down to 80 cm. On exposed surfaces the mean loss of pyroxene relative to feldspar is 103 cm3 m−2 of rock surface. With burial down to 50 cm in an arctic‐alpine Brown Soil the mean loss of feldspar relative to pyroxene is 179 cm3 m−2. These figures represent minimum amounts of weathering over about 9000 years. The results confirm the importance of chemical weathering in arctic‐alpine environments and the techniques may provide useful physical measures of degree of weathering for use in rate studies and relative‐dating.
Experimental frost and salt weathering of chalk—II
Authors: Jerwood L. C. , Robinson D. A. , Williams R. B. G.
Published: February 2007

Experiments are described in which chalk cubes were soaked in solutions of either sodium chloride, sodium sulphate, or magnesium sulphate at concentrations of 5·5 per cent and 12·5 per cent, or in a mixed solution of sodium chloride and sodium sulphate or in distilled water. After removal of excess liquid, the cubes were subjected to six freeze–thaw cycles with temperatures ranging from either +15 to −10°C or +15 to −30°C. The results confirm that frost weathering can be enhanced by the presence of certain salts, but the extent of weathering was much less than that previously reported for samples frozen totally immersed in the same liquids. Evidence is presented which suggests that salt crystallization is the major weathering process operative when non–immersed samples are frozen but a combination of frost and salt weathering operates when fully immersed samples are frozen.
Influence of lithologic erodibility on alluvial fan area, western white mountains, California and Nevada
Authors: Lecce Scott A.
Published: February 2007

Differences in lithologic erodibility and sediment storage within a drainage basin affect the relationship between alluvial fan area and drainage basin area along the western White Mountains. Large fans are produced by basins underlain by resistant rocks, which have steep and narrow trunk stream canyons with little sediment in storage. Small fans are produced by basins composed of erodible lithologic units, which have wider valley floors, lower valley‐side slopes, and considerably more sediment stored along trunk stream canyons than is the case in basins underlain by resistant rocks.
The weathering rates of some sandstone cliffs central Weald, England
Authors: Pentecost Allan
Published: February 2007

Short‐term (1‐30 months) weathering rates were obtained for steep cliffs of Cretaceous Ardingly Sandstone in southern England, using a new photographic method. Mean rates for an exposed and a sheltered outcrop were 0.11 and 0.033 mm a−1 respectively. Significant (p < 0.1) positive correlations were obtained with illumination and algal biomass and a significant negative correlation (p < 0.05) with slope angle. There was no correlation with grain size, porosity, or mean surface temperature. Highest weathering rates were observed on south‐ and west‐facing exposed cliffs. The results are discussed with reference to algal growth, climate, and wind direction.
Statistical analysis of factors influencing Cliff erosion along a section of the West Wales coast, U.K.
Authors: Jones D. G. , Williams A. T.
Published: February 2007

Cliff erosion along a section of the West Wales coastline is described. Rockfalls, mudslides, and retreating fencelines are evidence of current activity. Measurements over a two‐year period (1983‐85) gave mean annual recession figures of up to 0.25 m yr−1 for glacial embayments. Wave refraction modelling and longshore beach surveys confirmed the existence of ‘high’ and ‘low’ beaches. Factors influencing variation in recession rates were identified and measured. Regression analysis suggested that the volume of beach‐face material was the dominant explanatory variable in short‐term cliff erosion.
Behaviour of beach profiles during accretion and erosion dominated periods
Authors: Thom B. G. , Hall W.
Published: February 2007

Beach profiles have been surveyed at monthly intervals between 1972 and 1988 at Moruya on the South Coast of New South Wales, Australia. Four profile sites have been used as a data set to provide an understanding of changes to beach volume, width, and shape. Moruya beach represents a moderately high energy, microtidal environment, which responds in a dramatic way to major storm events such as those experienced in the mid‐1970s. This study distinguishes between profile characteristics associated with such a period (erosion‐dominated or EDP) compared with periods when accretion dominated (ADP) accompanied by foredune expansion in both height and width.
Sediment transport by burrowing mammals, Marin County, California
Authors: Black Thomas A. , Montgomery David R.
Published: February 2007

Field observations suggest that burrowing activity is the primary mode of sediment transport currently active in a small grassland drainage basin in Marin County, California. Spatial concentrations of the 1150 gopher mounds surveyed vary from 0‐16 mounds m−2 on interfluves to 0.32 mounds m−2 on sideslopes and in the topographic hollow, with localized concentrations of up to 2.88 mounds m−2 on the margins of the colluvial deposit. Simple models of sediment transport by burrowing activity yield estimates of between 0.91 and 2.33 cm3 cm−1 yr−1 for the basin as a whole, with absolute minimum and maximum rates of 0.48 and 631 cm3 cm−1 yr−1. These values are similar to those previously estimated for this area (Lehre, 1982) and are nearly an order‐of‐magnitude less than average long‐term sediment transport rates at the same site (Reneau, 1988).
GIS techniques and statistical models in evaluating landslide hazard
Authors: Carrara A. , Cardinali M. , Detti R. , Guzzetti F. , Pasqui V. , Reichenbach P.
Published: February 2007

Geographical Information Systems (GIS) and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard.

From a small drainage basin located in Central Italy, relevant geological and geomorphological factors were collected and processed by applying GIS technology. In particular, modules were used which both generate high‐fidelity digital terrain models and automatically partition the terrain into main slope‐units. The resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope‐unit. Although not lacking drawbacks, the method proved to be a feasible and cost‐effective approach to landslide susceptibility assessment and mapping.
Assessment of the sensitivity of the landscape in a sample area in Hungary for climatic variability
Authors: Kerényi Attila , Csorba Peter
Published: February 2007

In the northeastern part of Hungary near the township of Tokaj a landscape research project has been performed in a 9 km2 area. The aim of this study is to examine the possibilities of expressing the climatic sensitivity of the given small landscape unit by analysing the capabilities of such a small sample area and synthésizing the data obtained. The landscape analysis consisted of field and laboratory measurements, theoretical calculations, analyses of maps, as well as the construction of thematic maps (on the scale of 1:10000) and cartograms.

In view of climatic sensitivity four of the landscape factors were regarded as crucial: (1) the water budget of the soils, (2) the thickness of the soils and loose sediments, (3) insolation, and (4) land use. By synthesis of these factors a five‐grade climatic sensitivity map was produced. On the basis of the areal proportion of the different classes of sensitivity it was established that the study area is moderately sensitive to climate. Examination of the moisture content of soil clearly indicated different responses of the areas from the different sensitivity classes to changes in temperature and precipitation. The four main landscape factors selected proved to be useful in the rough delineation of the classes on the climatic sensitivity map. However, the use of the other landscape factors improved its accuracy.
The influence of sediment supply on the channel morphology of upland streams: Howgill Fells, Northwest England
Authors: Harvey A. M.
Published: February 2007

Previous work on stream channels in upland areas of Britain has demonstrated a close control over channel morphology and stability by the rate of coarse sediment supply from the hillslopes of the catchment. Streams fed by large amounts of coarse sediment develop unstable, wide, often braided channels, whereas those with limited coarse sediment supply develop stable, much narrower, often meandering channels. The sediment supply from hillslopes is controlled by thresholds of hillslope stability, storm event frequency, and the coupling between the hillslopes and the channel. Climatically‐induced changes in any of these three factors may have implications for channel morphology and stability. This paper examines these implications in British upland fluvial systems, with particular reference to the Howgill Fells, Cumbria, in the contexts of the adjustment of stream channels to sediment supply from erosional gully systems, and their response to and recovery from major flood events.