inscription
PORTAIL D'INFORMATION GÉOGRAPHIQUE

Résultats de la recherche (2358 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
  • Central African forest cover revisited : a multisatellite analysis
  • Afrique ; Afrique centrale ; Carte de la végétation ; Centrafricaine, république ; Congo ; Couvert végétal ; Forêt ; Phytogéographie ; Plante cultivée ; Savane ; Télédétection
  • Africa ; Central Africa ; Central African Republic ; Congo ; Cultivated plants ; Forest ; Phytogeography ; Plant canopy ; Remote sensing ; Savanna ; Vegetation map
  • Photographic evidence of rate of development of plant cover on the emergent island Anak Krakatau from 1971 to 1991 and implications for the effect of volcanism
  • Biogeography ; Indonesia ; Island ; Photointerpretation ; Plant canopy ; Population dynamics ; Vegetation ; Volcanic eruption ; Volcanism
  • Photographs of the vegetated North and East Forelands of Anak Krakatau, which emerged from the sea in 1930 and was totally devastated by volcanic activity in 1952/53, provide some evidence of rate of change of plant cover from grassland to woodland
  • Does plant cover structure in rural areas modify climate change effects?
  • Atmospheric circulation ; Climatic variation ; Evapotranspiration ; Global change ; Heat flow ; Land use ; Plant canopy ; Poland ; Rural area
  • This paper shows that : modification of the plant cover in an agricultural landscape influences the vertical flux of sensible heat; the changes in land-use pattern influence the vertical fluxes of sensible and latent heat at the scale
  • Influences of micro-relief patterns and plant cover on runoff related processes in badlands from Tabernas (SE Spain)
  • Almería ; Arid area ; Badland ; Infiltration ; Microrelief ; Plant cover ; Rainfall simulation ; Rill wash ; Sediment budget ; Slope ; Soil erosion ; Soil properties ; Spain
  • have been selected and the following surface properties, as variables under study, have been measured : surface area occupied by cracks, rock fragments, lichens, and plants; also the surface roughness under dry conditions (before rainfall
  • Land-cover change and forest institutions: a comparison of two sub-basins in the southern Siwalik hills of Nepal
  • Deforestation ; Environmental management ; Forest ; Himalaya ; Land use ; Nepal ; Plant cover ; Watershed
  • institutional structures were said to explain these land-cover changes. - (DWG)
  • An experimental study of infiltration and erosion under slope gradients and vegetal covers
  • China ; Experimentation ; Infiltration ; Plant cover ; Raindrop erosion ; Rill wash ; Slope ; Slope gradient ; Soil erosion ; Soil properties ; Splash
  • The effect of slope gradient and vegetal cover on soil infiltration and erosion were studied with field simulator, at the suburbs of Zhanjiakou city, Hebei Province, North China, on a loess hill. Discussion of the results.
  • Spatial patterns of soil crusting and their relationship to crop cover
  • Agricultural practice ; Duricrust ; England ; Experimentation ; Geographical information system ; Micromorphology ; Photogrammetry ; Plant cover ; Rainfall simulation ; Soil ; Soil properties ; Splash ; United Kingdom ; West Sussex
  • The interactions between the spatial pattern of soil crust development and crop cover conditions are investigated through controlled laboratory experiments using rainfall simulation. The experimental responses are monitored by using terrestrial
  • The influence of plant cover and land use on slope-channel decoupling in a foothill catchment : a case study from the Carpathian Foothills, southern Poland
  • Agricultural land use ; Carpathian Mountains ; Experiment plot ; Land use ; Plant cover ; Poland ; Rill wash ; Sediment transport ; Slope gradient ; Soil erosion ; Suspended load ; Watershed
  • This paper examines the influence of plant cover and land use on slope-channel decoupling in the Stara Rzeka Stream catchment and its subcatchment Dworski Potok Stream. The results show that transport and export of the material on the slopes depend
  • on the morphology of the slope and on the agricultural use of the area. The mosaic of fields which are used differently makes the soil wash process very intensive only if the slopes are ploughed and unprotected by a dense cover of vegetation. Footslope areas
  • and flat valley bottoms covered with grass function as a barrier separating the slope and the river bed.
  • Land use/cover changes and vulnerability to flooding in the Harts catchment, South Africa
  • Geographical information system ; Inundation ; Land use ; Northern Cape ; Plant cover ; Remote sensing ; South Africa ; Statistical analysis ; Vulnerability ; Watershed
  • The purpose of this study is to determine the hydrological impacts of land use/land cover change in the Harts catchment from 1990 to 2010 using an integration of remote sensing, GIS and statistical methods. The modifications of natural vegetation
  • cover have led to modified runoff production and consequently to changing flow regimes in the Harts catchment. The coupling of surface observations, remote sensing and statistical analysis demonstrated the impacts of changes in land use/land cover
  • Refugees, land cover, and environmental change in the Senegal River valley
  • Africa ; Desertification ; Environment ; Mauritania ; Migration ; Plant cover ; Refugees ; Remote sensing ; Sahel ; Senegal ; Soil ; Soil erosion ; Valley
  • This paper seeks to explore the complex relationships between land cover, environmental change and forced migration in the middle valley of the Senegal River, attempting both to identify the nature of environmental impacts of forced displacements
  • with specific reference to land cover, and to examine the social, political and economic circumstances in which these are exacerbated or reduced. The paper also examines the role of land regulation in influencing the observed patterns of land cover change.
  • Comparability and subjectivity of land cover maps produced with digital image classification techniques : some recent experiences from Denmark and northern Germany
  • Automated mapping ; Classification ; Comparative study ; Denmark ; Geographical information system ; Germany ; Image processing ; Land use ; Plant cover ; Remote sensing ; Satellite imagery ; Schleswig-Holstein ; Thematic mapping
  • This paper discusses issues related to the operationalisation of land cover mapping from image data. Specifically, it presents the methods and experiences of 2 recent land cover mapping projects, covering Denmark and parts of the German state
  • Land cover changes between 1958 and 1986 in Kalu District, Southern Wello, Ethiopia
  • Aerial photography ; Environmental degradation ; Ethiopia ; Geographical information system ; Land use ; Plant canopy ; Vegetation dynamics
  • %) because of clearing of vegetation and remaining open area increased the most (333%). Area under cultivation remained about the same. Authors call for rehabilitation off degraded hillslopes with little or no plant cover. - (SLD)
  • Two aerial photographs from 1958 and 1986 are digitized in TIFF format and imported into thinkspace's Map Factory. Nine land cover categories were distinguished and their areas were compared for the two dates. Shrubland decreased the most (-51
  • Assessment of the effects of biophysical and anthropogenic factors on woody plant encroachment in dense and sparse mountain grasslands based on remote sensing data
  • and mid-2000s were analyzed by supervised classification for identification of land cover types. The transition matrix indicated that shrublands were the most dynamic plant communities. Generalized additive mixed models (GAMMs) were used to identify
  • This study assessed woody plant encroachment below potential tree line in the Central Pyrenees of Spain and the association of this encroachment with changes in land use. Remote sensing data from Landsat-5 Thematic Mapper (TM) from the mid-1980s
  • biophysical and anthropogenic factors that were significantly correlated with woody plant encroachment of dense and sparse grasslands. Distance to the nearest woody plant habitat (shrub or forest) was the most strongly correlated factor with woody plant
  • encroachment of both types of grassland. This factor explained 69% and 71% of the variance in models of dense and sparse grasslands, respectively. The observed changes in land cover indicated that land cover has become more homogeneous.
  • Plant cover and standing crop sampling procedures for the Canadian high Arctic
  • Air temperature ; Climate fluctuation ; Diurnal variation ; Geomorphology ; Mountain ; Plant cover ; Poland ; Temperature
  • This paper adresses the matter of the differentiation of thermal conditions in the near ground air layer at Hala Gaşienicowa, as well as their relationships with plant cover, shape of relief and exposure to the sun. Mean daily air temperature
  • Geomorphic and forest cover controls on monsoon flooding, central Nepal Himalaya
  • Deforestation ; Discharge ; Flood ; Geomorphometry ; Himalaya ; Hydraulic works ; Inundation ; Monsoon ; Nepal ; Plant canopy ; Regional planning ; Watershed
  • Deforestation is often blamed as the principal cause of flooding during the monsoon period. However, bank-fall discharge at 22 stream crossings provide data to show that 82 percent of its veriation had nothing to do with forest cover. - (DWG)
  • Estimation of land coverage from a land cover classification derived from remotely sensed data
  • Classification ; Data processing ; Discriminant analysis ; LANDSAT ; Land use ; Plant canopy ; Remote sensing ; Thematic Mapper ; United Kingdom ; Wales
  • This paper aims to illustrate the estimation of land cover class coverage from an image classification. It focuses on a case study which aimed to derive accurate estimates of the coverage of industrially despoiled land in administratively defined
  • Trampling damage to vegetation and soil cover within the Burren National Park, Mullach Mor, Co. Clare
  • Biogenic action;Biogenic process ; Biogeography ; Degradation ; Environment ; Fauna ; Ireland ; National park ; Plant canopy ; Soil erosion ; Vegetation
  • Between 1986 and 1992, surveillance of three selected paths revealed a pattern of increasing damage to vegetation and soil cover. An attempt was made to quantify the extent of trampling damage, and to examine possible causes of observed spatial
  • Determination of vegetation cover fraction by inversion of a four-parameter model based on isoline parametrization
  • Plant cover ; Remote sensing ; Spectral reflectance ; Vegetation ; Vegetation index
  • Land use ; Landscape ; Norway ; Perception ; Plant canopy ; Protected area
  • This article uses an activity-based understanding of landscape to explore values related to perceived land cover diversity. Perceptions within two user groups in a mountain area in western Norway are related to a simultaneous land cover survey
  • , and compared to experts’ evaluations of land cover and to the aims of landscape protection in the area.