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In the badlands of the Upper Llobregat basin, vegetation is sparse and heterogeneous. The harsh conditions generated with the formation of the badlands involve a regressive succession. On the upper part of the slope, a sharp change can be seen between dense communities and denuded badland slopes. Nevertheless, recolonization of the badlands rarely occurs. Scarce seed availability or low capacity of...
The quantification of element pools and their changes in time is an important part of the analysis of ecosystems. This quantification is more difficult in soils with rock fragments because of their heterogeneity and because of the difficult analysis of the rock fraction for the pool substance. Repeated sampling and geostatistical analysis were used to quantify spatial heterogeneity in rock fragment...
Lakes are excellent repositories of air-borne and especially stream-borne materials. It has long been recognised that lake sediments contain a strong record of catchment soils via the inputs of minerogenic and chemical erosional products. To these may be added a variety of palaeoecological indicators including pollen, fungi, Sphagnum leaves and faunal remains. Pollen analysis, in particular, enables...
Field observations in central Belgium indicate a significant soil degradation process which has hitherto not been considered in assessments of soil erosion rates: i.e., soil losses due to root crop harvesting (SLRH). The objectives of this study were: (1) to assess SLRH for two commonly grown root crops in Belgium, i.e. chicory roots and sugar beet, (2) to investigate some factors controlling the...
Four representative profiles of poorly developed soils on consolidated material were studied in the Sierra de Carrascoy (SE Spain). The soils, with A-A/R or A-C/R type profiles, have medium-low contents of organic carbon and nitrogen, and calcium carbonate occurs in only one of the profiles. The pH in aqueous suspension is slightly alkaline. The cation exchange capacity is medium-low, but varies slightly...
In northern Ecuador, soils of high altitude grasslands (paramos) are mainly non-allophanic Andisols developed on Holocenic volcanic ash. These soils have a high water retention capacity and are the ''water tank'' of central Ecuador. To assess the effect of land use (burning and tillage) on soil hydrodynamic properties, rainfall simulation was conducted at two different sites. At Pichincha near Quito,...
Surface runoff and soil erosion are major threats to sustainable agriculture and mapping regional erosion risk is increasingly needed by national and international environment agencies. Because erosion results from the interaction of several parameters which vary in space and time, no simple model can take into account all relevant factors, particularly in cultivated areas where human influences are...
The evaluation of soil susceptibility to runoff and water erosion in the field is often expensive or time-consuming. Several authors have reported that susceptibility is linked to aggregate stability, whose determination is far easier. However, this susceptibility has generally been deduced from rainfall simulation experiments on sieved soil samples, whose behaviour is not always representative of...
Under semiarid environments where surface runoff takes place, the role of water erosion in the removal of seeds and then in the plant establishment and distribution is unknown. Within the scientific literature, data about the size and shape of seeds exist, but little information can be found about the susceptibility of seeds to be removed by water erosion processes. These data are important not only...
Estimating catchment scale soil loss based on rainfall simulators is often hampered by the difficulty to scale up simulator results. Our objective was to develop and test a method for estimating catchment scale soil loss based on observed rainfall using a variable intensity rainfall simulator in an erosion-sensitive catchment in semiarid Tunisia. A 7-year period, 1992-1999, with observed sedimentation...
The cover provided by forest vegetation makes it possible to fight erosion efficiently. Furthermore, vegetation barriers can also play a major role by trapping eroded sediments and thus vegetation located downslope of a gully can be important. The objective of this study is to highlight the role of vegetation distribution in a marly gully in reducing sediment loss at the outlet. To do this, sediment...
In dispersive marls near Vera, badland gullies are eroding into a previously stable matorral-covered landscape. This relatively recent activity was probably triggered by minor climatic or land-use change. In this landscape, Calvo-Cases and Harvey [Earth Surface Processes and Landforms 21 (1996) 725] argued that new gully-head slopes with differing aspect represent a sequence of progressive erosion...
The understanding of soil erosion processes and the development of accurate erosion prediction models require understanding of detachment, deposition, and sediment transport in rills. The objectives of this study were to determine whether sediment transport capacity is a unique value for given soil, flow rate, and slope, and to determine if equilibrium sediment concentration in the rill obtained by...
The co-ordinated European research project Wind Erosion and Loss of SOil Nutrients in semiarid Spain (WELSONS) was carried out from 1996 to 1999 to understand and predict the potential impacts of land-use change and management on soil degradation by wind erosion on agricultural land in Central Aragon, a semiarid desertification-threatened region in NE Spain. This paper gives a description of the project's...
Models of two processes (saltation and sandblasting) that lead to fine dust release in arid areas have recently been combined to form a dust production model (DPM), the physical bases of which are summarized. In order to validate DPM at field scale, its predictions in terms of horizontal and vertical mass fluxes are compared to direct measurements made in natural conditions on a silt loam soil in...
Several land use scenarios were developed for the 3.5 km 2 Danangou catchment on the Chinese Loess Plateau. These scenarios consist of four groups of three scenarios each: one group is based on the present land use distribution, the other three (alternative land uses) on a redistribution of land use according to slope gradient, soil type, slope aspect and land form. For example, cropland areas...
The islands of Azores are of very recent volcanic origin and their soils have special physical and chemical characteristics because of the specific circumstances of their formation from the volcanic materials, their young age and the presence of allophane. To assess and understand the hydrologic behavior of these soils under agricultural practices, the deterministic model OPUS was tested and calibrated...
The extensive soil erosion in Iceland during the past millennium has led to an irregular distribution of soil organic carbon (SOC). Intact and fully vegetated areas typically have Andosols with large amounts of organic carbon, whereas eroded areas are barren deserts with little organic carbon. We estimate the amount of organic carbon eroded during the past millennium is 120-500x10 6 t, whereas...
The area burned by wildfire in the states of Arizona and New Mexico in the southwestern US has been increasing in recent years. In many cases, high severity burns have caused dramatic increases in runoff and sediment yield from burned watersheds. This paper describes the potential and limitations of the HEC6T sediment transport model to describe changes in channel scour and deposition following the...
Extensive soil surface observations and measurements were conducted in Normandy on loess soils prone to surface crusting in order to understand the spatial distribution and temporal variability of soil surface characteristics involved in erosion processes. A database composed of more than 5000 soil surface observations at the field or plot scale was analysed. We classified these observations according...
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