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Three lunette dunes occur on the southern shore of a pan on the farm Buffelsfontein above the Great Escarpment in the northeastern part of the Eastern Cape Province, South Africa. The two inner lunettes are formed of silt and clay, and the third of fine sand. The location of these dunes is anomalous as lunette dunes are rare in the wetter parts of the southern African subcontinent. The two inner lunette...
The year 1994 saw the publication of several important volumes on soil classification. The USDA Soil Conservation Service issued the sixth edition of its Keys to Soil Taxonomy, including significant changes in the Aridisol classification. At the 15th World Congress of Soil Science (WCSS) in Acapulco, Mexico, the new Draft World Reference Base for Soil Resources, published by ISSS/ISRIC/FAO, was distributed...
Sediment source fingerprinting can provide information on the contribution of various sediment sources to the suspended load of a stream. This study was conducted to evaluate the potential of SEM/EDS analysis (scanning electron microscopy/energy dispersive spectrometry) to fingerprint two types of topsoil in a research basin: a black, chernozemic, farmland soil and a grey, podzolic, forest soil. Simulated...
Rainfall erosivity was characterized for the Guinea Savanna, Forest and Coastal belts of southeastern Nigeria (4° and 7°N; 6°30′ and 9°30′E). The highest maximum rainfall amounts ranged from 117 to 183 mm per rain event whereas the maximum 6-minute intensities ranged from 191 mm h −1 to 254 mm h −1 Advanced storms were dominant in the region. The values of the Kowal and Kassam kinetic...
Previous studies carried out by the authors and other references collected from the literature have shown the inadequacy of most rainfall erosivity indexes and specially the Wischmeier rainfall erosivity index, for properly estimating erosivity in southern Portugal and in Mediterranean climates. In order to measure raindrop size distributions of natural rainfall automatically and continuously, a device...
In his 1990 paper (Catena, 17: 175–183), Jan de Ploey proposed a system whereby catchments are viewed as functional units in which geomorphic work results from the combined effects of water erosion and mass movements. His measure of erosional susceptibility of catchments, E S , introduced the gravitational potential in addition to the kinetic energy of the eroding agents. This modelling of...
Geomorphology claims an expertise in the study of soil erosion and the development of conservation solutions. Yet what are presented as “facts” about erosion, especially in developing countries where the need for conservation is greatest, is usually unhelpful and sometimes wrong. To understand why the scientific message becomes distorted, geomorphologists should see themselves as actors on a political...
Bed-load transport experiments have been conducted in a steep gravel-bed open ditch. This initially straight ditch has been neglected for many years and looks at present like a second-order natural stream channel. The channel flows through a spruce forest and several log-jams have produced chutes and pools, creating supplementary roughness. The total shear stress has been evaluated using the slope-hydraulic...
Soil-surface seals and crusts resulting from aggregate breakdown reduce the soil infiltration rate and may induce erosion by increasing runoff. The cultivated loess areas of northwestern Europe are particularly prone to these processes.Surface samples of ten tilled silty loamy loess soils, ranging in clay content from 120 to 350 g kg −1 and in organic carbon from 10 to 20 g kg −1 ,...
The concept of Cumulative Erosion Potential (CEP) proposed by De Ploey, Kirkby and Ahnert in 1991 (Earth Surf. Process. Landforms, 16: 399–409) provides a simple climatic index of erosion potential based on annual rainfalls and their distribution, which is assumed to be exponential (or gamma with shape parameter 1). A modified CEP (CSEP) is presented here, extending the original in three ways. First,...
A modelling approach is used to estimate some effects of changed climate upon rates of soil erosion on agricultural land on the UK South Downs.Previous studies have concentrated only on estimating shifts in long-term mean erosion rate: these were found to be approximately linear. However such simple shifts mask changes in the underlying distributions of annual erosion. A first series of simulations...
This study analyses the between-catchment variability of rill volumes produced by concentrated flow erosion during winter in the northern part of the Paris Basin. The working hypotheses were that (i) runoff concentrates along channels determined by topography or by agricultural practices; (ii) rill length is a major component of rill volume variability on a catchment scale; (iii) rill cross-sectional...
Several pedological (water retention capacity, hydraulic conductivity, distribution and stability of aggregates, organic matter content, texture) and vegetal charateristics (litter production and litter decomposition, below ground biomass), have been studied in a transect of the Experimental Field of El Ardal (SE, Spain). This transect reflects several typical land use types of a Mediterranean semi-arid...
Soil degradation, by water and wind erosion is a matter of growing concern in Europe. Caesium-137, paired with conventional methods, is used in many countries to assess the extent of soil erosion. This technique was tested in a small watershed of the Laonnois area (Parisian Basin) which has been monitored for several years by traditional computerized and automatic techniques.This study makes possibe...
This article is based on an unpublished manuscript by the late Prof. Dr. Jan De Ploey. It focusses on the erosional susceptibility of catchments in terms of total energy input by the meteorological factors water and wind (E S -model).The form and the universal character of the basic expression of the erosional susceptibility are explained. Applications of the model are illustrated for different...
Microplot experiments using a portable rainfall simulator were carried out in April 1992 on 15 Turkish soils with textures ranging from clay loam to loamy clay and slopes from 3° to 12°. In order to determine the effects of a change in land use on infiltration and erosion, pairs of sites with soils developed on identical parent material were chosen. Several physical and chemical properties of the...
Extensive afforestation using Pinus and Eucalyptus has taken place in Calabria since the early 1960's to control expansion of calanchi and biancane. In 1978 three small catchments were established near Crotone to monitor the effect of afforestation on hydrological response and sediment yield. In 1992, rainfall simulation experiments were carried out on plots in these catchments to determine more precisely...
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