Rock fragments in top soils: significance and processes
Rock fragments in soil: surface dynamics
Erosion des sols ; Granulométrie ; Hydrologie ; Propriétés du sol ; Roche ; Sol ; Utilisation du sol ; Variation climatique ; Variation spatiale
Climatic variation ; Grain size distribution ; Hydrology ; Land use ; Rock ; Soil ; Soil erosion ; Soil properties ; Spatial variation
to the definition and measurement of rock fragment content in top soils, the density of soils containing rock fragments, the spatial distribution and movement of rock fragments in top soils, the effects of rock fragments on some key hydrological processes, thermal
This introductory paper reviews various aspects of rock fragments in top soils. Such information is required in particular for predicting the impact of climatic or landuse changes on the response of these soils. Particular attention is paid
Spatial distribution of surface rock fragments along catenas in semiarid Arizona and Nevada, USA
Rock fragments in soil: surface dynamics
Arizona ; Bassin-versant ; Catena ; Domaine semi-aride ; Erosion des sols ; Etats-Unis ; Fragment de roche ; Modèle ; Nevada ; Pente de versant ; Prévision ; Roche ; Sol
The major objectives of this study are to determine if a slope gradient-surface rock fragment cover relation exists on various catenas of semiarid Arizona and develop an equation to describe this relation.
Spatial distribution of rock fragments in cultivated soils in northern Ethiopia as affected by lateral and vertical displacement processes
Distribution spatiale ; Domaine aride ; Domaine semi-aride ; Désertification ; Ethiopie ; Fragment de roche ; Pente de versant ; Pratique culturale ; Ruissellement ; Sol ; Sol cultivé
Agricultural practice ; Arid area ; Cultivated land ; Desertification ; Ethiopia ; Rill wash ; Semi-arid area ; Slope gradient ; Soil ; Spatial distribution
Although, in semi-arid environments, rock fragments at the soil surface and within the topsoil play an important role in desertification control, little is known about their spatial distribution. Therefore, this study analyses spatial patterns
of rock fragment cover along catenas, and the vertical variations in volumetric rock fragment content in soil profiles in the highlands of Tigray, northern Ethiopia. Natural and anthropogenic processes inducing these patterns are assessed.
Quelques structures spatiales (celles du tissu construit ou celles des utilisations du sol) montrent des processus de fragmentation dans deux directions. La discontinuité augmente parce que les éléments constituants se séparent davantage. De plus
, leur façon de s'organiser varie. Les processus de fragmentation ont probablement une relation entre eux, et ils exercent une influence sur la croissance de la ségrégation spatiale et sur la conformation d'un modèle de ville de genre granulaire
The relation between surface rock-fragment cover and semiarid hillslope profile morphology
Rock-fragment cover on hillslope surfaces profoundly influences the operation of hydrologic and geomorphic processes on those surfaces. The purpose of this investigation was to examine the spatial variability of rock-fragment cover on morphological
units of hillslopes in southeastern Arizona. Simple statistical models, based upon hillslope gradient as well as a soil-slope factor were developed and validated for the estimation of percent rock-fragment covers on these units.
Arizona ; Land ; Phoenix ; Rural area ; Spatial analysis ; Spatial scale ; Spatial variation ; United States of America ; Urban area ; Urban fragmentation
A partir de l’exemple d’un ensemble de villes de l’aire métropolitaine de Phoenix, les AA. étudient les principaux problèmes méthodologiques liés à la modification de l’échelle de la fenêtre d’étude et à l’analyse de la fragmentation foncière. Dans
échelle sur les analyses des gradients de fragmentation rurale-urbaine puis évaluent le choix des cercles concentriques par rapport auxt transects. Ils concluent que cette nouvelle approche est la mieux adaptée pour représenter les modèles de la
Effects of rock fragments on soil erosion by water at different spatial scales: a review
Rock fragments in soil: surface dynamics
This paper reviews the various effects of rock fragments on soil erosion by water. Since these effects are scale dependent, they are investigated at three different nested spatial scales: the micro-, the meso- and the macroplot. For each scale
the corresponding process mechanism are discussed. Particular attention is paid to the effects of rock fragment cover on the intensity of soil erosion processes. The scatter of the data indicates that a given rock fragment cover can have different efficiencies
Effect of rock fragment embedding on the aeolian deposition of dust on stone-covered surfaces
Belgique ; Distribution spatiale ; Eolien ; Expérimentation ; Fragment rocheux ; Galet ; Granulométrie ; Poussière éolienne ; Vitesse du vent
Aeolian dust ; Aeolian features ; Belgium ; Experimentation ; Grain size distribution ; Pebbles ; Spatial distribution ; Wind speed
This study investigates how the deposition of dust is affected when rock fragments become gradually more embedded in the ground or, inversely, become more concentrated on the surface. Experiments were executed in an aeolian dust wind tunnel with 8
Temporal and spatial dimensions of newly incorporated municipalities in the United States
Collectivité locale ; Différenciation spatiale ; Délimitation ; Etats-Unis ; Fragmentation urbaine ; Pouvoir local ; Suburbanisation ; Ville
Delimitation ; Local authority ; Local government unit ; Spatial differentiation ; Suburbanization ; Town ; United States of America ; Urban fragmentation
Etablissement d'un contexte temporel pour ces municipalités de 1950 à 2010. Le déclin enregistré au cours de la période a des implications profondes pour la fragmentation des métropoles et les choix publics. Dans un deuxième temps, établissement
Element-pool balances in soils containing rock fragments
spatial heterogeneity in rock fragment content. Cs 137 measurements were used to quantify fine-earth contamination of dry-sieved and washed rock fragments because they are nondestructive and allowed for repeated analysis of the same sample. The Cs 137
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. Repeated sampling and geostatistical analysis were used to quantify
technique therefore allows an easy and less laborious estimation of the part of other element pools associated with rock fragments than direct measurements.
Aeolian dust ; Aeolian features ; Experimentation ; Rock ; Spatial variation ; Wind speed
on the pebbles, on the deposition of dust between and underneath the pebbles, and on total dust deposition was measured separately. Air flow separation seems to play a primary role in the spatial distribution of dust deposition within a rock fragment field
The effect of rock fragment cover on the deposition of airborne dust was examined in a wind tunnel. Four parameters were studied: pebble size, pebble flattening, cover density and wind speed. The effect of these parameters on the deposition of dust
Field-scale estimation of the volume percentage of rock fragments in stony soils by electrical resistivity
Analyse quantitative ; Bassin parisien ; Beauce ; Eau du sol ; Fragment de roche ; France ; Géophysique ; Modèle ; Propriétés du sol ; Résistivité électrique ; Sol ; Sol pierreux
Bassin parisien ; Beauce ; Electrical resistivity ; France ; Geophysics ; Model ; Quantitative analysis ; Rock fragment ; Soil ; Soil properties ; Soil water ; Stony soil
This paper presents a method that uses field spatial electrical resistivity measurements to determine the volume proportion of rock fragments. Based on the hypothesis that the electrical resistivity signal noise increases as the proportion of rock
fragments increases, a model was developed that uses the standard deviation of the apparent electrical resistivity measurements over a small area as an indicator of rock fragment contents. The model was tested on 3 study areas of several hectares containing
soil units with varying quantities of rock fragments in the Beauce region (Villamblain, France). The developed model strongly depends on the water content in the soil and the rock type and must be calibrated in each context. Nevertheless, estimations
of the rock fragment content in stony soils can be performed efficiently in the surface horizon as well as all along the soil profile.
The assessment of the effect and function of non-fragmented landscape areas with minimal disturbances for vertebrata with large spatial requirements can involve some methods. The more commonly-used methods of analysis and evaluation of such areas
Microclimate ; Spatial variation ; Temperature ; Urban climate
A l'intérieur d'un fragment urbain de quelques centaines de mètres carrés peuvent être enregistrés des écarts de température dépassant 6°C, par nuit claire et non nuageuse. Le contraste thermique spatial dépend de la nature du substrat et de la
Appropriation of land ; Espace vécu ; Lisbon ; Portugal ; Segregation ; Sociological integration ; Urban area ; Urban district ; Urban fragmentation ; Young people
L’A. examine la manière dont on a formulé au Portugal la ségrégation socio-spatiale et la relation entre les jeunes et le quartier en situation de relogement.. On analyse les nouvelles possibilités que la politique d’habitat social crée pour la
promotion de la mixité sociale, justifiant la prise en compte de contextes territoriaux fragmentés.
Metropolitan fragmentation and neo-localism in the periphery : revisiting the case of Curitiba
Brésil ; Curitiba ; Développement durable ; Fragmentation urbaine ; Paraná ; Politique du logement ; Politique urbaine ; Transport public ; Utilisation du sol
Brazil ; Curitiba ; Housing policy ; Land use ; Paraná ; Public transport ; Sustainable development ; Urban fragmentation ; Urban policy
Les AA. analysent le développement urbain de la ville de Curitiba au travers du vide institutionnel et de l’émergence d’un régime spatial décentralisé. Ceci a pour résultat un système de gouvernance néo-locale fragmentée. Ils concluent par les défis
auxquels se trouve confronté ce nouveau régime en matière d’association des stratégies socio-spatiales, économiques et environnementales en vue de promouvoir un avenir urbain plus durable.
Patterns of rock fragment cover generated by tillage erosion
Intensively cultivated areas in the upper part of the Guadalentin catchment (southeast Spain) show a systematic spatial pattern of surface rock fragment cover. The objective of this paper is to quantify and to explain this spatial rock fragment