bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic conductivity in frozen soils
Authors: Burt T. P. , Williams P. J. 
Published: February 2007

AbstractAn 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

AbstractIn 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

AbstractArroyo 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

AbstractIn 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.
Experimental and micromorphological investigation of erosion and redeposition of loess by water
Authors: Mücher H. J. , De Ploey J. 
Published: February 2007

AbstractIn 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

AbstractIn 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

AbstractThe 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

AbstractHydro‐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

AbstractRainfall 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

AbstractThe 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

AbstractA 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

AbstractIt 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

AbstractThis 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

AbstractOne 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

AbstractThe 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.
Slope stability and valley formation in glacial outwash deposits, North Norfolk
Authors: Richards K. S. , Anderson M. G. 
Published: February 2007

AbstractDry 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

AbstractPrevious 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

AbstractApplication 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

AbstractThe 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

AbstractThe 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.