inscription
PORTAIL D'INFORMATION GÉOGRAPHIQUE

Résultats de la recherche (1114 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
  • Sediment yield and spurious correlation. Toward a better portrayal of the annual suspended-sediment load of rivers
  • Two alternative methods for portraying the annual suspended-sediment load of a river are suggested. One method consists of plotting supended-sediment load (tons per year) against distance downstream. Such plots indicate that annual suspended
  • -sediment load does not necessarily have a linear relationship with distance. The second method consists of plotting annual suspended-sediment load against drainage-basin area. Both methods more accurately portray fundamental relations between annual
  • sediment load and drainage-basin characteristics than does the yield-area relation because spurious correlation is avoided.
  • Suspended sediment load of Bulgarian rivers
  • Annual variation ; Bulgaria ; Data base ; Drainage network ; Human impact ; Hydraulic works ; Sediment budget ; Statistics ; Stream ; Suspended load
  • This paper reports the results of continuing studies of sediment loads in Bulgarian rivers, with the purpose of elucidating the natural and regional distribution of natural and anthropogenic changes in sediment load through time.
  • A load cell based continuous recording bedload trap
  • England ; Instrumentation ; Research technique ; Sampling ; Sediment load ; Sediment transport ; Stream ; United Kingdom
  • This paper reviews the design and performance of pit-type bedload traps that use pressure pillow and load cell systems to measure the accumulation of sediment. A low coast load cell bedload sampler design is presented. Temperature correction
  • is shown to be necessary for each load cell. The results of laboratory and field calibration are presented and design improvements suggested. Field data output is illustrated.
  • The effects of hurricane Hugo on suspended-sediment loads, Lago Loιza basin, Puerto Rico
  • Dam ; Hurricane ; Precipitation ; Puerto Rico ; Rill wash ; Sediment transport ; Suspended load ; Watershed
  • The sediment data that were collected during Hurricane Hugo (five sediment stations and 11 rain gauges were operating in the Lago Loιza basin) presented an opportunity to quantify the transport of suspended-sediment loads into Lago Loιza
  • Accelerated erosion in the Nara Kosi watershed, Central Himalaya, India. Part I. : sediment load
  • Agriculture ; Deforestation ; Erosion rate ; Gully erosion ; Himalaya ; India ; Sediment transport ; Soil erosion ; Solution load ; Suspended load ; Watershed
  • Measurements of suspended and dissolved loads in this watershed suggest that deforestation and agricultural activities increase the rates of erosion by a factor of five to ten. - (DWG)
  • Sediment transport, delta growth and sedimentation in Lake Nigardsvatn, Norway
  • Delta ; Glacial erosion ; Glacier retreat ; Lacustrine sedimentation ; Lake ; Norway ; Proglacial lake ; Sediment load ; Sediment transport ; Suspended load ; Varves
  • Charge en suspension ; Charge solide ; Delta ; Erosion glaciaire ; Lac ; Lac proglaciaire ; Norvège ; Recul du glacier ; Sédimentation lacustre ; Transport sédimentaire ; Varve
  • The lake, Nigardsvatn, has been studied since 1968 in order to obtain data on solid material carried by the meltwater stream from the glacier, both in suspension and as bottom load. Between 70 and 85% of the suspended sediment has been deposited
  • on the lake bottom, forming annual varves. The coarse material has been deposited in a delta, the formation of which started in 1968. Its growth, and hence the volume of total annual bottom load, has been surveyed annually for the past 36 years. In 1969
  • the entire bottom load was collected by building a fence-like net across the river. If conditions remain constant, the lake will be completely filled in about 500 years.
  • Suspended sediment load during floods in a small stream of the Dolomites (northeastern Italy)
  • Alps (The) ; Carrying capacity ; Discharge ; Flood ; Grain size distribution ; Italy ; Mountain ; Summer ; Suspended load ; Watershed ; Years 1990-99
  • Suspended sediment load was analyzed in a small, high-gradient stream of the Eastern Italian Alps which was instrumented to measure discharge and sediment transport. The ratio of suspended to total sediment yield and the relations between sediment
  • concentration and water discharge were analyzed for 7 floods which occurred from 1991 to 1996 in summer and autumn. Different patterns of hysteresis in relation between suspended sediment and discharge were related to types and locations of active sediment
  • sources. An analysis of grain size has shown that erosion areas on hillslopes were the main sources of suspended load.
  • Discharge and sediment-load characteristics of the Hilda rock-glacier stream, Canadian Rocky Mountains, Alberta
  • Water discharge and sediment load characteristics of the Hilda rock-glacier stream are described for portions of the 1985 and 1986 ablation seasons. The hydrological behavior of the Hilda rock-glacier stream suggests that the rock glacier acts
  • as a buffering factor in basin runoff as compared with a similar glacierized basin. In addition, the rock glacier acts conservatively in sediment release from the basin and promotes denudation by dissolution and material transport as dissolved load.
  • Suspended sediment load estimation and the problem of inadequate data sampling : a fractal view
  • Fractals ; Mississippi ; Missouri ; Model ; Sampling ; Statistics ; Stream ; Suspended load ; United States of America ; Watershed
  • Use the notion of fractal theory to obtain important information regarding the possibility of temporal transformation of sediment load data is the subject of this study. As a first step, daily suspended sediment load data observed in the Mississippi
  • behaviour in the suspended sediment load data, suggesting the possibility of transformation of data from one scale to another using a multi-dimensional model.
  • Measurement of bedload in rivers in Erosion and sediment yield : some methods of measurement and modelling.
  • Only in recent years have bed load data for rivers existed in sufficient quantity and reliability to facilitate a better understanding of the bedload transport process. Data for the East Fork River, Wyoming indicate that when sand-size particles
  • are dominant as bedload the bed load accounts for about half the total load. The examples of the Tanana, Snake and Clearwater Rivers indicate that for gravel bed rivers the bed load probably accounts for less than 10 % of the total load.
  • Understanding watershed suspended sediment transport
  • Bibliography ; Forecast ; Methodology ; Model ; Statistics ; Suspended load ; Water quality ; Watershed ; Years 2000-2009
  • This paper synthesizes a variety of methods adopted in suspended sediment monitoring, estimation and modelling for understanding sediment transport processes and determining the suspended sediment load. Methods for sediment monitoring are described
  • in terms of direct and indirect approaches. Different approaches toward the establishment of a sediment rating curve are examine thoroughly. Techniques of sediment modelling are summarized via depiction of various hydrological and sediment models
  • at the watershed scale. The paper ends with the discussion of future developments in suspended sediment studies at the watershed scale.
  • Characteristics and quantity of pebble bed load at Gezhouba Project of the upper reaches of the Yangtze
  • Carrying capacity ; China ; Fluvial processes ; Jiangsu ; Petrography ; Sediment load ; Stream
  • This paper summarizes the results of investigation of the pebble bed load (PBL) with d > 10 mm at the Gezhouba Project and makes proposals for analyzing the characteristics of the PBL by using the geological and geomorphological method
  • Suspended sediment and bed load problems of the Upper Rhine
  • in the petrographic composition of the bed load material as well as in its particle size distribution.
  • The suspended sediment discharge of the River Euphrates at Haditha, Iraq : an assessment of the potential for establishing sediment rating curves
  • The results presented indicate that in this case, suspended sediment rating curves established using infrequent samples (2 - 4 samples per month) can be employed to provide estimates of annual loads and of mean annual loads which are within 20
  • % and 5 % of the actual loads respectively. This level of accuracy is likely to be acceptable for most applications.
  • The effect of man-made reservoirs on sediment load in Proceedings.
  • Bohemia ; Czech Republic ; Fluvial processes ; Geochemistry ; Sediment load ; Suspended load
  • The results of four-year measurement of suspended sediments in the Holedeč profile at the Blšanka river in the NW Bohemia. The main attention is paid to the typology of the individual regime situation and to geochemical analysis of suspended
  • sediment particles and active bank sediments. - (MS)
  • Suspended sediment load in the Amazon Basin : an overview
  • The central objective of this report is to summarize the available sediment and sediment transport data for the Amazon River and its major tributaries and to present some previously unpublished data.
  • Relationship between suspended sediment load, channel geometry and land area increment in the Yellow River Delta
  • Channel geometry ; China ; Delta ; Environmental management ; Huang He ; Human impact ; Hydraulic works ; Sediment transport ; Stream ; Suspended load
  • The aims of this work are : to determine what is the critical suspended sediment load needed in order to maintain the land balance of the Yellow River Delta for 2 periods before and after 1976 (the last time the channel shifted); and to examine
  • the variation in the channel geometry and gradient in response to changes in sediment load and delta area at the river mouth. These results are of importance for the management of the lower Yellow River channel and the delta.
  • Comparison of fractional bed-material load computation methods in sand-bed channels
  • Carrying capacity ; Grain size distribution ; Methodology ; Sediment load ; Statistics ; Stream ; Suspended load
  • This paper presents a comparison of different fractional bed-material load computation methods in sand-bed channels. These methods include the direct computation by size fraction approach of Einstein, Laursen and Toffaleti; the bed material fraction
  • Geochemical tracing and spatial evolution of the sediment bed load of the Romaine River, Québec, Canada
  • Bank erosion ; Canada ; Carrying capacity ; Fluvial dynamics ; Geochemistry ; Holocene ; Principal components analysis ; Quebec ; Sediment load ; Stream ; Tracer
  • In order to characterise the present river bed load sources, sediment transport and sedimentary connectivity, a study was conducted to document the compositional continuum of the lower 300 km portion of the river. Bed load samples were collected
  • . This is further supported by the sedimentary budget calculated from the annual sedimentary input derived from erosion rates of the river banks, from sediment bed load measurements at 3 gauging stations and from calculated bed load transport capacity at these 3
  • Euclidean distance coefficients were also calculated between consecutive samples along the river revealing major bed load compositional breaks. These results indicate a longitudinal fractionation of the bed load along the 300 km course of the river