bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral translocation of soil plasma through a small valley basin in the Northaw Great Wood, Hertfordshire
Authors: Huggett R. J.
Published: February 2007

The paper looks at the process of lateral translocation in a small valley basin from the Northaw Great Wood, Hertfordshire. The valley basin comprises four lithostratigraphic units (London Clay and Pebble Gravel, and the others a mixture of these two), which were initially established in the field by a rough assessment of texture. Particle size analysis validated the lithostratigraphic units as delineated in the field; it was found unnecessary to alter the boundaries of the units. Patterns of lateral translocation of silt and clay (measured by the hydrometer method) and the amorphous colloidal hydrous oxides and hydroxides of Al, Fe, Mn and Si (measured in oxalate solution by atomic absorption spectrophotometry) are inferred from balance sheets of the relative gains and losses of the materials. Materials from horizons formed in lithostratigraphic units derived from London Clay are balanced against a clay dilution factor; those from the lithostratigraphic unit of Pebble Gravel against the dilution of sand on a clay‐free basis. The results lead to the following conclusions about the process of lateral translocation: it has been a significant contributor to soil development; larger amounts of material have moved down‐slope towards the hollow than over the nose because there has, theoretically, been more throughflow in the hollow; for some materials there has been less down‐slope transport in lower horizons owing to less throughflow in them.
Adaptive adjustment of channel geometry
Authors: Bennett R. J.
Published: February 2007

This paper constructs a model of channel geometry composed of three subsections: a steady‐state submodel, a gradedstate submodel, and a stochastic error submodel. With the aid of this representation of the morphology of channels, the at‐a‐point changes in geometry can be reproduced by a simple recursive equation of autoregressive, moving‐average form which is derived from methods used in the statistical analysis of time series. A set of height loss data for three Japanese rivers derived from Yatsu's (1955) paper is used to determine the effect of bed material changes on adaptations within the graded‐state submodel of the channel. The results of analyzing the autocorrelation function, spectrum, and adaptive parameter shifts within this model can be used to infer that significant changes in the amplitude of height change variation, and a shift to higher frequency oscillations of bed forms are associated with the shift in bed material conditions.
The differential impact of some soil loss factors on flow, runoff creep and rainwash
Authors: de Ploey J. , Savat J. , Moeyersons J.
Published: February 2007

The Hortonian model of runoff flow which had been thought to be applicable in arid areas has previously been shown not to be valid, notably in Israel, where inverse relations have been observed between slope angle, and runoff discharge and slope erosion. The paper discusses laboratory experiments on simulated slope conditions in a rather arid environment. It is shown by rain simulation on granite grus that infiltration capacity is a function of rainfall intensity, slope angle and runoff discharge. The infiltration capacity f can equal the rainfall intensity beyond a critical distance x(m) so that discharge becomes constant. Debris covers affect runoff hydraulics, especially on poorly cohesive soils, and both slow downslope and upslope movements which correspond to the process of so‐called runoff creep can occur. Coarse debris and grass covers, as roughness factors, induce hydraulic discontinuities and activate local turbulent flow and slope erosion. Instead of being merely protective elements these factors tend to catalyze the slope wash, in comparison with naked surfaces, if the Reynolds number of the flow exceeds a certain critical value.
Debris flows on vegetated screes in the black mountain, Carmarthenshire
Authors: Statham Ian
Published: February 2007

The Black Mountain Scarp in Carmarthenshire is currently being modified by debris‐flow activity along gullies cut into the vegetated scree, which is a persistent feature of the scarp‐front. Low angled, concave debris flow cones are accumulating at the mouths of the gullies.

Mean rate of sediment yield from the sides of one gully was estimated to be 8·4 m3 in one year, and 9·8 m3 was shifted out of the gully by a single debris‐flow in the same year. Movement by other transport processes, such as streamflow, was negligible in the gullies. No new gullies are being initiated at the present and all of them appear to be in a similar state of development. Consequently, it appears that some marked environmental change was responsible for initiating gully erosion. If present rates of gully‐erosion are representative of the past, the gullies are only about 540–700 years old and may possibly have been initiated by sheep‐grazing in the area.
An inexpensive circuit design for the acoustic detection of oscillations in bedload transport in natural streams
Authors: Anderson M. G.
Published: February 2007

A circuit design is reported which is demonstrated to be capable of receiving and recording the underwater sound of inter‐particle collisions on natural stream beds during the process of bedload transport. Field trials were undertaken in a natural stream with sand‐sized bedload particles. The results obtained, for a constant stream stage, give support to the idea of the occurrence of short period oscillations in the rate of bedload transport.
Flow and sedimentary processes in the meandering river South Esk, Glen Clova, Scotland
Authors: Bridge John S. , Jarvis Jack
Published: February 2007

Channel geometry, flow and sedimentation in a meander bend of the River South Esk were studied from bankfull stages (January–February) to low water stages (May) in 1974. Bed topography varied little over the study period, showing a typical pool and ripple geometry. Variation of mean depth and velocity with discharge differed from section to section around the bend, due primarily to locally varying flow resistance with stage.

The flow pattern for all stages was dominated by a single spiral over the point bar, with a development zone at the bend entrance. Deviation of bed shear stress from the mean flow direction was in general accord with theory, especially for high stages. The use of a uniform longitudinal water surface slope in the calculation of bed shear stress is not justified because of a complicated water surface topography, also such calculated shear may not represent effective bed shear on grains, as it accounts also for energy losses associated with secondary flows.

Dunes covered much of the bar at high stages, with increasing proportions of ripples, sand ribbons and lower phase plane beds at low stages. Local flow resistance generally decreases from dunes, diminished and ripple‐backed dunes, ripples, sand ribbons to plane beds, and bed forms are predicted quite well by the stream power‐grain size scheme.

Mean size, sorting and skewness of sediment over the bed changes little with stage. In general, size decreases, sorting improves and skewness changes from positive to negative from the talweg to the inner bank, and in the downstream direction. Allen's (1970a, b) force balance equation for moving bed load particles is supported for bankfull stage, with some reservations, and textural characteristics are explained by progressive sorting in the direction of sediment transport.

Large‐scale trough cross stratification (with some flat bedding) formed at high stage by dunes (and lower phase plane beds) dominates the point bar sediments. Alternations of fine‐medium sand (often cross‐laminated) and vegetation‐rich layers result from periodic deposition on the grassed upper bar surface.

Fining upwards sequences produced by lateral channel migration are modified by a coarsening upward subsequence in the upstream bar region where spiral flow is developing from the bend upstream.
Disturbed periodic model for river meanders
Authors: Ferguson R. I.
Published: February 2007

Although river meanders are not perfectly regular their serial statistics show periodic tendencies which cannot be explained by previous stochastic models. The regular and random approaches to meander geometry can be reconciled in a disturbed periodic model with separate scale, sinuosity, and irregularity parameters. Meandering is viewed as a deterministic oscillation but irregularity is introduced by quasi‐random variability in valley‐floor topography and materials. For stability such a model needs either a Bagnold type limit on bend curvature or frictional damping of the oscillatory response to individual disturbances. Realistic statistical properties are derived for the second case. The differential equation for direction can be approximated by a second‐order autoregression, which generates realistic simulated patterns and gives a good fit to natural direction series.
Hydraulic conductivity in frozen soils
Authors: Burt T. P. , Williams P. J.
Published: February 2007

An apparatus has been developed for investigation of hydraulic conductivity of frozen soils. The test procedure is isothermal and involves the passage of water from one reservoir into the frozen sample and out of the frozen sample into a second reservoir. The water in the reservoirs remains unfrozen because it contains dissolved lactose. The concentration of lactose is such that, initially, the water in the reservoirs is in thermodynamic equilibrium with the water in the soil. On application of pressure to one reservoir a known hydraulic gradient is established and flow takes place. Flow is shown to vary linearly with hydraulic gradient. The hydraulic conductivity coefficient depends on soil type and temperature and is related to the unfrozen water content. At temperatures within a few tenths of 0°C the coefficient apparently ranges from 10−5 to 10−9 cm sec−1, and decreases only slowly below about −0·5°C. Soils known to be susceptible to frost heave are shown to have significant hydraulic conductivities well below 0°C.
Bed forms and unsteady processes: Some concepts of classification and response illustrated by common one‐way types
Authors: Allen J. R. L.
Published: February 2007

In natural environments, where unsteady flows prevail, the common one‐way bed forms (ripples, dunes, antidunes, parting lineations on plane beds) show delayed responses to changes of flow. A dual classification may then be necessary for the features:

1. Geometric, with no implication of flow conditions.

2. Geometric‐hydraulic, in which the shape of the observed forms is combined with the character of the concurrent flow.

The delayed responses arise because, under the simplest steady‐state equilibrium conditions, the bed forms behave deterministically as populations, which take average dimensions controlled by the bed‐material and/or flow conditions. The response of the bed to a change of flow is a rearrangement of the particles forming the bed in an attempt to meet the new conditions. The rate of rearrangement, however, is controlled by the sediment transport rate, in turn determined by the flow conditions, and so is finite.

Two specific mechanisms of change of opposing tendency are quantifiable:

1. Creation‐destruction of forms, where the new forms are better adjusted than predecessors.

2. The imperfect modification of existing forms during their life‐spans.

Both rates may be controlled by a combination of flow variables, the attributes of the bed forms, and ‘constants’ specific to each kind of form. A better knowledge of the unsteady responses of these bed forms should increase our understanding of and control over river and tidal systems and may provide models for a better appreciation of still larger features in landscapes and waterscapes.
Observations of contemporary arroyo cutting near Santa Fe, New Mexico, U.S.A.
Authors: Malde Harold E. , Scott Arthur G.
Published: February 2007

Arroyo cutting that began in the American Southwest in the 1880s is associated with sudden runoff, a circumstance characteristic of this semiarid region in which occasional intense rainfall exceeds the capacity of the ground to absorb water. This report describes two arroyos in an area of moderately dissected bolson deposits southwest of Santa Fe, Cañada de la Cueva and Pueblo Cañon, where arroyo cutting since 1970 has been closely related to runoff from summer rain. The area is vegetated chiefly by grama grass and scattered juniper. Cutting is monitored by repeated surveys of channel floors, cross‐sections, and headcuts, and by repeated photographs taken as stereopairs. Rainfall and discharge are measured simultaneously in 5‐minute intervals by dual digital recorders at a gauging station on Cañada de la Cueva (drainage area 4.64 km2). Discharge has been as much as 18.2 m3/s from rainfall of 25.2 mm. The maximum 15‐minute intensity for this storm was 64.0 mm/hr, and runoff was 7.9 mm. The flood peak arrived in 20 minutes, by which time 80 per cent of the rain had fallen, and the flow subsided to a tenth of its maximum in less than an hour. This storm at Pueblo Cañon (drainage area 13.3 km2 above the place of measurement) resulted in an estimated discharge of 140 m3/s, and features produced by hail on the channel floor suggest that the duration of flow could have been as brief as 30 minutes. Observed increments of headward cutting at Cañada de la Cueva range from 0.28 m for 1.8 mm of runoff to 4.9 m for 12 mm of runoff. Aggregate cutting in 5 years has been as much as 13.7 m, resulting in erosion of 570 m3 of alluvium. Headward cutting near the mouth of Pueblo Cañon has been observed in increments of 10.3, 14.6, and 20.7 m, for an aggregate of 45.6 m, as measured from 1971 to 1974. This cutting removed 1,770 m3 of alluvium.
Sodium sulphate weathering and the disintegration of Mohenjo‐Daro, Pakistan
Authors: Goudie A. S.
Published: February 2007

In Pakistan various brick building structures are currently disintegrating in the Indus Valley. These include the Harappan site of Mohenjo‐Daro. The environment of this site is described, the nature and speed of the disintegration problem is outlined, and the cause of disintegration is discussed Weathering occurs in association with the development of salt efflorescences and some bricks disintegrate only a few years after being laid down. Chemical and X‐ray diffraction analyses show that the predominant salt is the sodium sulphate mineral thenardite. The reasons for its effectiveness are discussed. They include its high solubility, the rapid change of solubility with temperature, and its hydration characteristics.
Slope form and basal stream relationships: Some further comments
Authors: Richards K. S.
Published: February 2007

The nature and strength of the correlation between stream gradient and valley side slope angle are seen to vary according to the order of the stream segment. In addition, it is suggested that the relationship will depend on the efficiency of slope processes, and that this may contribute to tye different from of relationship obtained in different regions.
Experimental and micromorphological investigation of erosion and redeposition of loess by water
Authors: Mücher H. J. , De Ploey J.
Published: February 2007

In the Laboratory of Experimental Geomorphology experiments were carried out on loess from the Pleniglacial A of the Weichselian. Most of the experiments had as their objective determination of the effect of slope angle, rainfall intensity, raindrop impact, added overland flow and concentrations of suspended material, on the erosion and redeposition of loess.

At various stages during the experiments, as well as at the beginning and end, undisturbed samples of loess were collected for micromorphological investigation.

—Pluvial runoff (overland flow with raindrop impact) supplied with or without terminal runoff, gave rise to laminated deposits, tightly packed and moderately differentiated in size and mineral species.

—After flow (the flow that occurs in the field during a short period after rainfall has ceased) and meltwater flow were simulated by terminal runoff. If the discharge and suspended load were moderate (respectively 0.81/min/dm and 20,000 mg/l), the sediments produced were very well laminated, well sorted and minerally differentiated, and loosely packed. In an exceptional case, with a very high discharge (81/min/dm) and suspended solid load (150,000 mg/l), the sediments were virtually unlaminated, and consisted of very loosely packed aggregates, which must have been formed during transport.

—Splash (material transported exclusively under raindrop impact) was applied successively to: calcium carbonate rich loess, decalcified loess and Ap‐material from a loess soil profile. In these three sediments no lamination, sorting and practically no mineral differentiation were produced that could be observed in the thin sections. Comparing the laboratory results with the situation in two loess quarries, one near Leuven and one near Tongrinne (both in Belgium), the micromorphological interpretation of the sediments in the field ranged from the very simple to the very complex.

—The small quarry near Leuven contained a cross‐section through a gully filled with laminated calcareous loess. This sediment could be interpreted as having probably been formed by pluvial runoff alternating with after flow.

—The large quarry near Tongrinne was more complicated. The several deposits here could have been formed under conditions ranging from pluvial runoff alternating with after flow, to splash and/or meltwater flow with high wash‐load concentrations.

The micromorphological research suggested that the loess was not only reworked by meltwater but also by pluvial runoff; the latter being probably the most important process, at least during Early Weichselian times.
The widening of valley incisions by soil fall in a forested Keuper area, Luxembourg
Authors: Imeson A. C. , Jungerius P. D.
Published: February 2007

In the gently undulating Keuper region of Luxembourg valley incisions in mixed oak‐beech forests are being widened by a process of soil fall. This process is optimized by a number of ecological conditions. Soil profiles examined in the Deifebaach catchment, located between Larochette and Ettelbruck, generally have an abrupt boundary between the silty surface soil (A2 horizon) and the dense clayey subsoil (B horizon). This boundary is marked by the formation of a dense root mat. The subsoil contains a large proportion of oriented clay and is subject to swelling and also to dispersion. Clay particles translocated downwards increase the density of the subsoil and decrease its permeability. The soils are very poorly drained, being waterlogged for much of the year, and have experienced some fragipan development.

When the subsoil is exposed it disintegrates into an incoherent mass of aggregates and recedes beneath the root mat which supports the overlying material until it eventually collapses. The nature and amount of soil fall recession is examined along a 320 m reach of die Deifebaach. It was found that at least 30 per cent of the right bank and 40 per cent of the left bank are subject to recession by soil fall.
Splash erosion, animal activity and sediment supply in a small forested Luxembourg catchment
Authors: Imeson A. C.
Published: February 2007

The sediment supply of a first‐order catchment in the Luxembourg Ardennes is considered. In the absence of overland flow the most important process of sediment supply is splash erosion. This is confined to areas of exposed mineral soil produced mainly by the burrowing activity of animals. The amount of splash erosion reflects not only burrowing but also the yearly cycle of litter‐fall and decay. The concentration of suspended material in the catchment river is not related to the discharge but in most cases to rainfall intensity. Turbidity measurements made at 1‐minute intervals showed a considerable degree of detail which illustrated the role of splash in supplying sediment to the river, although other processes can be important. The difficulty of estimating the output of material from a small catchment by means of a simple rating curve is stressed as is the need to consider slope and sediment supply processes in an ecological context.
Chemical erosion in a forested watershed in the oesling, Luxembourg
Authors: Verstraten J. M.
Published: February 2007

Hydro‐pedological investigations were carried out in a small forested watershed on the Lower Emsian formations of the Lower Devonian in the Luxembourg Ardennes. These rocks consist of weakly metamorphosed shales and quartzites, of which only the shales are undergoing appreciable weathering, and are composed of quartz, sericite, albite and chlorite, with minor amounts of haematite (goethite) and traces of pyrite, rutile and apatite. The alumino‐silicates react with CO2 charged water, forming kaolinite, with vermiculite and smectite as intermediate phases and releasing cations and silica for solution. From a hydrological study and a detailed programme of soil, spring and river water sampling the year could be subdivided into three characteristic hydrological periods. The runoff during these periods could be separated into various components, some of which have a characteristic water chemistry. The amount of material removed in solution was 7,448 kg for the years 1973/1974 and 1974/1975 (220 kg/ha/year). The output of material in solution is probably much greater than the output of material in suspension and as bedload. The chemical erosion rate could be calculated with these output data, after making allowance for atmospherically supplied materials and biomass recycling; it amounts to 4,435 kg (131 kg/ha/year), which is 59.5 per cent of the total solutional output.
Essential conditions of rainfall simulation for laboratory water erosion experiments
Authors: Th. Riezebos H. , Seyhan E.
Published: February 2007

Rainfall simulation is a technique which aids, under controlled conditions, the understanding of a part of the processes involved in water erosion. Simulation requires, that the relevant characteristics of natural rainfall be closely reproduced. Physical limitations and conflicting conditions obstruct the realization of a correct reproduction of all characteristics belonging to different kinds of natural storms.

A laboratory rainfall simulator, EROS MII, of the tubing type is under construction. The simulator is composed of 8 plexiglass boxes (50 × 50 × 5 cm) producing rainfall intensities between 1 cm/h and 15 cm/h.
Soil development models as a component of slope models
Authors: Kirkby M. J.
Published: February 2007

The interaction of slope profile models with soil profile models is discussed in general terms to show the external constraints on each individual soil profile which set it within its catena context. The soil profile models discussed are primarily chemical, and treat the soil hydrology as externally imposed. Soil inorganic minerals are treated as mixtures of elementary oxides, using modified values for Gibb's free energies which are approximately valid for silicates. Soil organic matter is considered to consist of carbohydrates, amino acids and lignins, in order to simulate soil organic matter distributions with and without vertical mixing. The soil CO2 distribution is simulated via gaseous diffusion of the CO2 produced by organic matter decomposition. Soil pH is calculated with reference to the CO2 distribution, and allows the solubility equations to be solved through the resulting inorganic soil profile. A worked example is given for a soil profile in equilibrium with given external rates of mechanical and chemical denudation.
The development of a laboratory set‐up to measure creep induced by freeze‐thaw cycles
Authors: Van Steijn H.
Published: February 2007

A laboratory set‐up for measuring creep is described. The main objective is the measuring of creep rates. In the present experiments freeze‐and‐thaw cycles are considered as one of the main causes for seasonal creep movements. The aim is also to take into consideration the influence of segregational ice on the rate of the movements. The goal of the first experiments described here is the development of an accurate equipment for measuring the actual creep rate. The experiments are carried out in the Laboratory for Physical Geography of the University of Utrecht (The Netherlands).
Problems in the estimation of short‐term variations in limestone erosion processes
Authors: Trudgill Stephen T.
Published: February 2007

It is suggested that the evolution of morphology on a hard rock surface should be studied at a micro‐scale. At this scale there is a reasonable chance of establishing the relationship between the operation of process events and the progression of erosion rates. Micro‐erosion meters and micro‐weighed weight‐loss tablets make this possible. However, installation and disturbance factors make it difficult to approach the theoretical limits of the techniques and at the present stage only seasonal differences in erosion rates can be identified with any real certainty. Measurements on a smaller time scale of about one month have, however, been gained but these results should be interpreted with caution in the light of the problems involved.
The behaviour of stones and stone implements, buried in consolidating and creeping Kalahari sands
Authors: Moeyersons J.
Published: February 2007

This study reveals that the Quaternary mantle of reworked Kalahari Sands undergoes a post‐sedimentary composite process at the archaeological site of Gombe (Kinshasa, Zaïre). There is a biological activity which consists of an upworking of soil particles, mainly by termites and worms. This causes a diminishing dry volume weight of the sediment. In response, the mantle reconsolidates.

When the soil surface is horizontal, the particles which are not brought up will sink down in the soil profile as a result of the reconsolidation. When the soil surface is inclined, it is only the resettlement of the sediment which can give rise to creep, caused by wetting and drying. Creep of the dead mineralogical material alone seems to be very improbable once the structure and settlement of the sediment are in equilibrium with a given slope. Only a new phase of bioturbation can induce further creep movements.

The experiments have shown that stone implements in reconsolidating Kalahari Sands do not exactly accompany the compaction movement of the sediment. Depending on their form, their size, their orientation and the water content of the sediment around them, stone implements can undergo differential movements during the reconsolidation process. This can result in a dispersion of the implements over levels of different ages.

As creep is a phenomenon, going hand in hand with the resettlement of the sediment after biogenic upworking, partially analogous movements of stone implements can be expected in a creeping Kalahari Sands mantle.

Partial or total reconcentration of the stone implements at the base of affective biogenic activity can be expected. This can lead to typical stone‐line profiles which must be interpreted very carefully.
The role of time and aggregate size in the crusting process
Authors: Farres P.
Published: February 2007

One of the fundamental mechanisms operative during pre‐overland flow soil erosion is crusting. The form of the crust, its relationship to infiltration, have been described by earlier workers. But the way in which a crust forms and develops through a single storm has not been considered. A set of controlled laboratory experiments were undertaken to look at this. In these experiments a constant rainfall intensity was used, and supplied by a rainfall simulator, the soil was held constant throughout the experiments. The areal development through a single storm event was looked at by means of time sequence air photographs, and the vertical development by the study of time sequence thin sections. The results show how crust formation may be regarded as a discrete rapid event with respect to time. The rapid development moves towards an equilibrium state prior to the initiation of overland flow. A model of the mechanisms of crust development is also formulated.
Fine‐sediment mineralogy of source rocks and suspended sediment, rother catchment, West Sussex
Authors: Wood Peter A.
Published: February 2007

The clay and silt mineralogy of the Cretaceous bedrocks of the Rother drainage basin is restricted to seven minerals. The mineralogy of soils and alluvium is similar to the bedrock upon which they are developed although minor variations can be found. The mineralogy of bedrock, soils and alluvium is reflected to some extent in the suspended sediment of rivers draining over them, and three different mineral assemblage zones are identified. Subtle controls of mineralogical variation in suspended sediment may include the ratio of groundwater/surface runoff contribution to river flow, rate of reaction of soil and bedrock to precipitation, preferential settling of non‐platy grains in quieter stretches of water, and the precipitation of material from solution as waters equilibriate with the atmosphere.
Determination of intersection points within a telescopic alluvial fan complex
Authors: Bowman D.
Published: February 2007

Delimitation of a single fan component within an alluvial fan complex system is facilitated by observing contour offsets on topographic maps which indicate the position of the intersection point. Two different types of intersection points are discussed. Israeli topographic sheets of the Dead Sea area provide examples.
Slope stability and valley formation in glacial outwash deposits, North Norfolk
Authors: Richards K. S. , Anderson M. G.
Published: February 2007

Dry valleys and gullies in fluvioglacial sands and gravels in North Norfolk are fossil forms. Interpretation of their origin demands detailed morphological analysis, but the inevitable ambiguities of form require additional information on the sedimentology of the deposits and associated regolith. Soil mechanical data and stability analysis predict the observed modal slope angles, assuming the water table to be at or near the surface. This suggests that valley formation involved impeded drainage, and slope processes such as shallow slab slides and solifluction over permafrost. The debris was subsequently evacuated from the valleys by meltwater. The stability analysis also explains the different modal slope angles observed at two locations. Slope angle frequency distributions are composite, however, and include data from varying locations up‐valley. Up‐valley variations in slope angle are seen to reflect variations in the nature of the regolith and consequent changes in soil mechanical properties, as well as changes in valley relief. The up‐valley trends in the nature of the regolith are commensurate with a model of headward valley erosion, with a ‘younger’, less weathered regolith at the present valley head.
The role of topography in controlling throughflow generation
Authors: Anderson M. G. , Burt T. P.
Published: February 2007

Previous studies of the downslope movement of soil moisture have been largely confined to two‐dimensional slope profiles—the influence of contour curvature (three‐dimensional) on moisture movement has received little attention. An automatic tensiometer system has been used to monitor soil moisture status continuously in a single hollow and adjacent spurs. Maximum saturated hillslope flow is shown to coincide with the stream discharge ‘throughflow peak’. Relative to the hollow, little saturation is evident at the base of the spurs. This subcatchment model is applied to a major portion of the catchment, showing the general importance of topography in the control of stream discharge.
An investigation of morphological zonation of beach rock erosional features
Authors: Hopley D. , MacKay M. G.
Published: February 2007

Application of one‐dimensional Fourier analysis to the erosional morphology of intertidal beach at a number of contrasting sites in North Queensland, Australia, confirms that there exists a zonation of hollows. Although different combinations of processes may be responsible for the morphology of each zone it is suggested that increasing case hardening and joint development with associated intermittent exposure of the beach rock may be the greatest influence on the development of erosion hollow zonation.
A landslip/debris flow in bilsdale, North York Moors, September 1976
Authors: Beven Keith , Lawson Andrew , McDonald Adrian
Published: February 2007

The conditions prior to and the site and results of a debris flow are described. Baseline data collected after this extreme event are outlined. Similarities between antecedent conditions of this flow and others reported in the literature are noted. From the field evidence comment is made on the mobile nature of the flow which may be analogous to spontaneous liquefaction in sands.
Morphology and mineralogy of red desert soils in the libyan sahara
Authors: Atkinson K. , Waugh B.
Published: February 2007

The occurrence of red desert soil profiles developed on Nubian Sandstone in the Libyan Sahara is discussed. From an examination of profile morphology in the field and the position of the soils at 970 m on an old land surface, it would be possible to regard them as desert paleosols formed under a previous humid climatic phase during the Quaternary. However, an investigation of the mineralogy of the soils and the underlying parent rocks strongly suggests that the properties of the soils are largely dependent on the parent material. Both have identical patterns of kaolinite content, haematite as the main ferric oxide, and similar proportions of quartz silt and coarse quartz sand. Therefore, the use of kaolinite and ferric oxides in interpreting past soil‐forming climates in arid regions needs to be carried out with caution, for in the present case such an interpretation would be unreliable.
Dynamics, sediment transport, and morphology in a tide‐dominated embayment
Authors: Sternberg R. W. , Marsden M. A. H.
Published: February 2007

Western Port, Victoria, Australia is a tide‐dominated embayment with an unusual and complex shape. Bottom currents and circulation and their effects on sediment processes were examined using instrumented tripods to measure currents, tides and wave activity, and to estimate sediment transport at nine locations in the bay. Overall bottom water movement patterns were determined by use of seabed drifters.

The characteristics of the bay reflect a small catchment and low freshwater and sediment input. A complex system of channels is flanked by extensive intertidal areas.

Tidal range varies up to more than 3 m, generating bottom currents up to 70cm s−1. Flow directions generally conform to channel alignments but major deviations are important. Net circulation in the bay is clockwise around the large central island. The ratio of tidal range to half‐tidal period (ΔH/ΔT) when compared with measured currents gave a method of prediction of the annual frequency distribution of maximum bottom current velocities.

Determination of threshold current velocities enabled prediction of annual frequency of bedload movement (generally 50–100 per cent of tide cycles). Bedload mass transport for all observed tide cycles was calculated, and estimates of annual mass transport capacity (between 102 and 106 g cm−1 a−1( were obtained from a relationship between predicted tidal conditions and mass transport.

Seabed drifters delineated the major bottom water movements in the bay and adjacent Bass Strait, and also detailed circulation patterns. This linked the data from the tripod stations, in particular patterns of ebb‐ and flood‐dominance.

A coherent picture of the processes operating in Western Port is presented by integrating these studies with corroborative studies of sediment distribution and morphology, hydrochemistry, and mathematical modelling. Some morphological characteristics related to tide‐dominance are discussed.
The evolution of fluviatile sediments as demonstrated by QDa‐Md analysis
Authors: McManus J.
Published: February 2007

The modification of scree sediments entering a stream is examined by QDa‐Md methods. Loss of fine or coarse subpopulations or both in combination from an initially symmetrical grain size distribution is shown to result in the dispersion of the QDa‐Md plots throughout an envelope typical of fluvial sediments. Natural plots from the Rivers Earn and Tay provide live examples of the transenvironmental trend patterns demonstrated.
Geometry of alluvial fans: Effect of discharge and sediment size
Authors: Le Hooke Roger B. , Rohrer William L.
Published: February 2007

The slope of an alluvial fan increases with increasing debris size and sediment concentration in the flow, and decreases with increasing discharge. Laboratory studies suggest that the discharge which controls this slope, or dominant discharge, is that which is equalled or exceeded one quarter to one third of the time that flow occurs on the fan. In contrast, the dominant discharge in perennial alluvial rivers is equalled or exceeded only about 5 per cent of the time that flow occurs in the river. The dominant discharge on fans increases with increasing debris size, reflecting the importance of threshold stress.

The slope of some natural and most laboratory alluvial fans is steepest on the flanks and gentlest along the axis. Consideration of the momentum of water debouching onto a fan at its apex suggests that the difference in slope between axis and flank should be greatest on steep fans composed of relatively non‐cohesive materials because on such fans higher discharges tend to flow down the axis, whereas lower discharges can be turned to course down the flanks. On fans with gentle slopes or composed of more cohesive material the higher discharges can also be turned toward the flanks, so on such fans the difference in slope between the axis and flank is less pronounced. Field and laboratory observations support this interpretation.

Because deposition at any one time on an alluvial fan is localized, some areas aggrade while others remain at a fixed elevation. This process is treated as a Markov process with the probability of diversion from an area of active deposition into an adjacent lower area increasing as the height of the active area above the mean or ‘ideal’ surface increases. Analysis of data from laboratory and natural fans suggests that the amplitude of such surface irregularities is greater on fans composed of coarser material. The data on natural fans also suggest an increase in amplitude of the irregularities with increasing fan area.
Causal and functional relations in fluvial geomorphology
Authors: Hey Richard D.
Published: February 2007

The concept of causality has been a fundamental principle of scientific investigation for many centuries. Recently, however, there has been a significant reappraisal of the philosophical basis of the concept of causality and this has important implications for future geomorphological research.

It is now recognized that there are two approaches to the study of relations between variables. Conventionally knowledge was divided into classes and, on the basis of time precedence, causal relations were defined. While this approach enables static systems to be analysed it does not apply to dynamic systems which exhibit mutual causality. This traditional view of knowledge became obsolete with the introduction of the concept of the continuum. Algebraic techniques now enable the solution of systems of simultaneous equations, provided that there are as many equations as unknowns. Significantly this approach applies to dynamic as well as static systems.

Further advances in fluvial geomorphological research are dependent on the adoption of mathematical reasoning. This will concentrate research on the mode and rate of operation of channel processes and feedback mechanisms. Given this information it will be possible to develop a static process‐response model to explain and predict channel response to a set of input conditions, and a dynamic model to simulate channel development through time and space.
Ground retreat and slope evolution on regraded surface‐mine dumps, waunafon, gwent
Authors: Haig Martin J.
Published: February 2007

Ground retreat was monitored on two vegetated and two unvegetated profiles over a five‐year period. The average annual retreat of the two unvegetated profiles was 5.84 mm and 3.62 mm; that of the two vegetated profiles 2.34 mm and 2.07 mm. Slope evolution was controlled by the mid‐slope‐ward migration of two zones of accelerated erosion and the resulting replacement of a central rectilinear slope segment by the upper and lower slope elements.
Stone chute development on a limestone scree
Authors: Loughran Robert J. , Loughran Ann I.
Published: February 2007

The modification of limestone scree slopes in North Yorkshire takes the form of downslope trains of finer stones. These features, termed stone chutes, usually coincide with a narrow defile in the limestone scar above. Investigations of four stone chutes below Raven Scar in Twisleton Dale revealed intermittent downslope movement of stones. On these coarse limestone screes, where there is insufficient fine material for debris flow formation, stone chutes are the visible evidence of slope evolution.
‘Bedload’ dynamics: Grain‐grain interactions in water flows
Authors: Leeder M. R.
Published: February 2007

Owing to experimental difficulties, the transport stage at which collisions between moving ‘bedload’ grains might become significant has never been investigated, yet the existence or otherwise of such collisions is of some importance in the understanding of the mechanics of sediment transport, in particular the theory developed by Bagnold. Application of the basic principles of gaseous kinetic theory to ‘bedload’ grains moving in saltant trajectories and the adoption of a ‘characteristic’ saltation path leads to the prediction that grain‐grain collisions should dominate in the transport of coarse sands over plane beds in water flows above a transport stage of about 2, i.e. when the mean boundary fluid shear stress exceeds the critical boundary shear stress for grain motion by about 4 times. Above this stage interrupted saltations should always occur, with the ‘bedload’ grains held above the stationary bed by a combination of fluid and solid momentum transfer mechanisms. A classification of the types of grain motions is given and evidence is presented for the existence of an upward decrease in grain collision frequency and of grain concentration at the top of the ‘bedload’ zone.
Discriminant analysis as a possible tool in landslide investigations
Authors: Reger James P.
Published: February 2007

As part of an investigation of mass movement on outslopes of contour surface‐mines in West Virginia, discriminant analysis was used to determine whether selected spoil properties could statistically distinguish failed and unfailed embankments. The analysis utilized the variables degree of saturation, liquid limit, and shrinkage limit, and the a priori assignment of samples into either actively failing, unfailed, or regraded categories.

Results were encouraging, with seventy‐four percent of the samples being correctly classified. All misclassifications involved samples from active or regraded landslides, suggesting the method was conservative.

Performance of discriminant analysis could probably be improved by modifying the sampling plan.
Sorted stripes orientated by wind action: Some observations from sub‐antarctic marion island
Authors: Hall Kevin
Published: February 2007

Sorted stripes found on the volcanic scoria and glacial deposits of sub‐Antarctic Marion Island indicate a distinct preferred orientation. Despite uniformity of slope and material, the stripes are predominantly aligned parallel to the wind. It is suggested that melting of needle ice by the early morning sun is of only limited importance in the sub‐Antarctic owing to the almost continual overcast conditions. The effect of the wind is so great that in exposed situations stripes are formed on horizontal surfaces.
Laboratory simulation of salt weathering processes in arid environments
Authors: Cooke R. U.
Published: February 2007

The equipment and techniques being used at Bedford College, London to simulate salt weathering processes in deserts are described in the context of a general discussion of the nature of salt weathering processes and approaches to studying them. An experiment based on the equipment and techniques is described: it is designed to test the durability of three building stones in the presence of several different saline solutions under conditions of surface temperature and relative humidity that are considered typical of hot deserts. The experiment, the first of a series, shows that Na2SO4 is the most effective of the salts used, and that susceptibility of the rocks to weathering is related to such rock properties as porosity, microporosity and water absorption capacity.
PLAN FORM AND PROFILE FORM OF HILLSLOPES
Authors: Parsons A. J.
Published: February 2007

For 27 hillslope profiles located within four first‐order drainage basins on the dip slope of the South Downs in East Sussex, contour curvature (P), measured in degrees per 100 m, is highly variable within any one hillslope. Hillslopes may be described as wholly concave in plan where P is less than −40, wholly convex in plan where P is greater than +40 and convexo‐concave in plan where P lies between −40 and +40. One measure of P taken at the profile sampling line is found to give a better estimate of P than measuring P at the steepest point on the hillslope. P is found to be significantly negatively correlated with slope in 38 per cent of cases, correlated with distance from the divide in 55 per cent of cases (positively where P<0 and negatively where P<0) and positively correlated with profile curvature in 70 per cent of cases. Implications of these correlations for hillslope process‐response models are discussed.
Experimental test of autosuspension
Authors: Southard John B. , Mackintosh Michael E.
Published: February 2007

The concept of autosuspension implies that if, in a flow transporting suspended sediment down a slope, the sediment adds more energy to the flow than it extracts, the concentration can rise to an indefinitely high level. This was tested in a small closed duct, with variable slope, connecting two free‐surface reservoirs. The sediment‐carrying flow could be recirculated continuously from the downstream end of the duct to the upstream end. For each of five sediment sizes ranging from 14 μm to 96 μm, two flows at the same discharge were run, one with zero slope and one with a slope chosen so that autosuspension should have been in effect. Something is wrong with the autosuspension criterion: in each set of runs, equilibrium suspended‐sediment concentrations were virtually identical in the two cases. Analysis of the term in the autosuspension criterion expressing work done by the flow to suspend sediment shows that this quantity is much smaller than is assumed in autosuspension, and so the criterion should have been even more strongly oversatisfied in our tests. Although both the energy‐expenditure form and energy‐contribution form in the criterion have a physical reality, comparison of the two has no relevance to the equilibrium state of the flow; autosuspension is based on an irrelevant system of energy bookkeeping. Suspension must be viewed as limited by factors involving alterations in turbulence structure leading to changes both in boundary resistance and in the ability of the flow to entrain and suspend sediment.