Original and secondary high-frequency sandstorm zones in the Loess Plateau region, China
Through analysis of the relationship between the mean annual number of sandstorms and the mean annual precipitation, an original sandstorm zone and a secondary high-frequencyzone of sandstorms have been defined. The latter is mainly formed
Higherfrequency acoustic measurements of swash processes
Charge du fond ; Chichester ; Déferlement ; England ; Géographie physique ; Houle ; Hydrologie marine ; Littoral ; Royaume-Uni ; Sédimentologie ; Transport à la côte ; Zone prélittorale
calibration of the probe confirmed the theoretical dependence of the local acoustic energy level on the bedload transport rate. A series of highfrequency measurements in the swash zones on the beach at Chichester Harbow are described.
Effects of high-magnitude/low-frequency fluvial events generated by intense snowmelt or heavy rainfall in arctic periglacial environments in northern Swedish Lapland and northern Siberia
Arctique ; Bassin-versant ; Bilan sédimentaire ; Débit de pointe ; Eau de fonte ; Etude comparée ; Laponie ; Pluie torrentielle ; Périglaciaire ; Russie d'Asie ; Sibir' ; Suède ; Transport sédimentaire ; Zone froide
. The results from these both arctic periglacial environments underline the high importance of high-magnitude/low-frequency fluvial events for the total fluvial sediment budgets of periglacial fluvial sediments. Restricted sediment avaibility is in both arctic
Atmospheric triggering and geomorphic significance of fluvial events in high-latitude regions
Magnitude and frequency in geomorphology
Arctique ; Bassin-versant ; Concept ; Eau de fonte ; Ecoulement ; Erosion ; Fréquence-magnitude ; Manteau nival ; Pergélisol ; Périglaciaire ; Slush de neige ; Spitsbergen ; Suède ; Svalbard ; Transport sédimentaire ; Zone froide
Strong annual variability and seasonal snow covers determine hydrological processes and related sediment displacements in high latitude regions. The most significant period for runoff and fluvial sediment transport is the snowmelt period in early
summer. Based on the discussion on general aspects of magnitude-frequency relations, atmospheric triggering and resulting hydrologic and geomorphic events in periglacial environments are analyzed with special focus on drainage basins in NW-Spitsbergen
High-resolution last deglaciation record from the Congo fan reveals significance of mangrove pollen and biomarkers as indicators of shelf transgression
Afrique ; Bio-indicateur ; Congo ; Cours d'eau ; Datation C 14 ; Déglaciation ; Embouchure ; Mangrove ; Niveau marin ; Palynologie ; Paléo-environnement ; Quaternaire ; Zone intertropicale
Africa ; Biological indicator ; C 14 dating ; Congo ; Deglaciation ; Mangrove ; Palaeo-environment ; Palynology ; Quaternary ; River mouth ; Sea level ; Stream ; Tropical zone
The AA. report here data on the occurrence and high abundance of Rhizophora pollen, in association with taraxerol, from a high-resolution Congo fan core covering the last deglaciation. An age model based on C 14 dates enables the temporal changes
in the percentage frequencies and flux of mangrove pollen, and in biomarkers, to be compared with pre-existing independent data on relative sea-level change in this region and with the hypismetric curve for the Congo margin. This approach therefore provides a basis
with which to test the hypothesis that high quantities of mangrove pollen can be used as an indicator of transgression across tropical and sub-tropical continental shelves.
Cordon littoral ; Dynamique littorale ; Géomorphologie littorale ; Hydrodynamique ; Littoral ; Pays-Bas ; Transport sédimentaire ; Zone intertidale
Coastal dynamics ; Coastal environment ; Coastal geomorphology ; Hydrodynamics ; Intertidal zone ; Netherlands (The) ; Sand bar ; Sediment transport
. The research focuses on processes associated with the transformation and breaking of high-frequency wind-waves near the inner of the two nearshore breaker bars of Egmond aan Zee (Central Dutch Coast). - (AGD)
Andes ; Creep ; Dépôt de pente ; Eboulis ; Granulométrie ; Géographie physique ; Géomorphodynamique ; Périglaciaire ; Texture ; Vénézuela ; Zone intertropicale
Sur un talus d'éboulis des Andes vénézueliennes, des cailloux choisis sur quatre courbes de niveau différentes ont été peints, et pendant 5,5 ans, le type et la longueur des déplacements ont été décrits. La relation magnitude/fréquence des
mouvements est différente suivant la texture du dépôt et les transects| ceci a été rapporté à des processus différents. Le creep par pipkrakes, des glissements à sec et des coulées de débris ont été les agents de transport les plus importants dans les zones
. Cs 137 activity in the floodplain stratigraphy showed a well-defined profile, with a clear peak at 115 cm depth. The high accretion rate over the last ca. 45 years is explained by the highfrequency of tropical cyclones near Fiji (40 since 1970) which
-September, the rainy season. Heavy rain evenys show no significant show no significant secular trend. There is a weak and non-significant upward trend in frequency of extremely high temperatures from the 1950s to the mid-1990s. But the number of hot events
Climate extremes for agricultural-pasture transitional zone, northern China are analyzed on the basis of daily mean temperature and precipitation observations for 31 stations in the period 1956-2001. Analysis season for precipitation is May
increases as much as twice since 1997. The frequency of low temperature events have been decreasing steadily since the 1950s.
Antarctique ; Cycle gel-dégel ; Fracture ; Géotechnique ; Impact ; Matériaux de construction ; Météorisation ; Radiation ; Roche ; Température ; Zone froide
Recent geomorphological studies have shown the importance of thermal stress in cold regions by means of high-frequency rock temperature data which can identify rates of temperature change in excess. The occurence of weathered material in cold
Analyse discriminante ; Appalachians ; Cône alluvial ; Cône de déjection ; Etats-Unis ; Géographie de l'Amérique ; Lave torrentielle ; Montagne ; North Carolina ; Piedmont ; Pléistocène supérieur ; Quaternaire zones moyennes ; Sédimentologie
At least two ages of fan deposits occur in the study area. The last episode of deposition may have taken place after climatic amelioration at the end of the Wisconsin, when increased precipitation and an abundance of frost-produced debris at higher
elevations probably temporarily increased the size and frequency of debris flows.
interpretation of daily pictures from satellites permits to estimate the frequences of cloudy patterns according to synoptic circulations in the middle latitudes, in the tropical latitudes and to explicit the interaction between high and low latitudes. Studies
of cloudiness over France and in the tropical zone illustrate the use of satellite imagery in the world climatology.
Rhythms in the geomorphological evolution and time-space related scale levels in the high latitudes
Avalanche ; Bassin-versant ; Coulée boueuse ; Echelle ; Géomorphologie ; Mouvement de masse ; Versant ; Vitesse d'érosion ; Zone froide
commence à se dégager une certaine cohérence entre les résultats obtenus par les différents AA.. En ce qui concerne les phénomènes brutaux et discontinus, l'inconnue majeur reste la période de retour et la relation fréquence/intensité des évènements. Quant
Capacité de charge ; Chenal anastomosé ; Cours d'eau ; Crue glaciaire ; Géométrie hydraulique ; Islande ; Transport sédimentaire ; Zone froide
is controlled by low frequency, high magnitude flow events, possibly associated with glacial outburst floods. This is in marked contrast to process-form relationships in more dynamic alpine proglacial channels that are characterised by high rates of sediment
The AA. studied soils at 6 sites at the German North Sea coast. At each site, 3 zones (low, mid, and high marsh) that differ in inundation frequency were analyzed. They found that organic carbon (OC) and nitrogen (N) contents increased significantly
with decreasing inundation frequency at all sites, while inorganic carbon contents decreased. The decrease in sea-derived OC was associated with an increase in C/N ratio, which can be attributed to the difference in the C/N ratios between sea- and land-derived
organic matter (OM) inputs. In the high marsh, a large proportion of the OC was sequestered in the coarse particle fraction, indicating that this OM is little stabilized.
Bassin-versant ; Coulée boueuse ; Dynamique de versant ; Eau de fonte ; Géomorphométrie ; Laponie ; Neige ; Risque naturel ; Suède ; Versant ; Zone froide
the snow cover during the initial period of snowmelt-runoff. In addition, release and movement of a high magnitude-low frequency slush torrent was documented on video and photographs. The results verify that the initiation of slush streams is confined
Measurements and observations comprised all energy balance components and meteorological conditions in the course of the snowmelt period, may and june 1995, as well as intra- and subnival meltwater flows and the formation of a saturation zone within
Conservation des sols ; Dégradation des sols ; Erosion des sols ; Gestion de l'environnement ; Indicateur ; Kenya ; Pratique culturale ; Risque ; Sol cultivé ; Zone intertropicale
Agricultural practice ; Cultivated land ; Environmental management ; Indicator ; Kenya ; Risk ; Soil conservation ; Soil degradation ; Soil erosion ; Tropical zone
in an agriculturally high potential smallholder farming system in Central highlands of Kenya. Survey data were assessed based on consensus views, percentage frequency and descriptive statistics. Eleven erosion indicators were identified and described in local language
Regionality of occurrence frequencies of various climatic types in the Mediterranean and its surrounding region
Circulation atmosphérique ; Classification ; Climat ; Domaine méditerranéen ; Géographie physique ; Méditerranéens, pays ; Précipitation ; Température ; Type de temps ; Variation interannuelle ; Zone climatique
This study aims to examine : 1) detailed regionality of Koppen's Mediterranean Climate type| 2) regional differences of the occurrence frequency of its type| 3) year to year variation of its occurrences, and 4) their relation to the general