Airborne Thematic Mapper ; BristolChannel ; Eau de mer ; Géographie physique ; Hydrologie marine ; MSS ; Royaume-Uni ; Swansea Bay ; Télédétection
Corrélation de données de simulations TM de 1982 sur la baie de Swansea et le BristolChannel en régression linéaire et multiple, avec les paramètres de la qualité des eaux (suspensions, salinité de surface, chlorophylle-a en concentration) mesurés
Les AA. comparent les imageries obtenues par le radar à synthèse d'ouverture du satellite SEASAT (en 1978) et par un sonar à balayage latéral, type WE MK3 (en 1983) dans le canal de Bristol (Angleterre). Les modifications de la rugosité de surface
Un modèle descriptif de la distribution des lapiez littoraux du détroit de Bristol est présenté. Les lapiez sont étudiés à l'aide d'une matrice altitudinale, et un paramètre de surface, l'indice de forme est fourni. Il est testé par la comparaison
Investigating the behaviour of two-dimensional finite element models of compound channel flow
This paper describes results from a recent study concerning the numerical modelling of compound channel flow using 2 generalized two-dimensional finite element codes specifically adapted to floodplain studies: RMA-2 and TELEMAC-2D. By application
[b1] Dept. of Geography, University of Bristol, Bristol, Royaume-Uni
sableuses (Scarweather Sand, nord du BristolChannel), les comparaisons des champs identifiés sur l'image avec les vecteurs de courants de surface (mesurés), les courants prédits et les courants observés simultanément au passage de l'avion font comprendre la
A new high space/time resolution distributed sensitivity analysis is presented and used to examine the impact of simple variations in initial conditions on inundation predictions derived from a two dimensional finite element model of river channel
[b1] University of Bristol, Dept. of Geography, Bristol, BS8 1SS, Royaume-Uni
, the BristolChannel, and the Severn Estuary) for the occurrence of tsunami-like waves that, in the absence of associated seismic activity, they recognize as meteo-tsunamis. This coastal hazard has resulted in damage and loss of life and should be considered
Meteorological tsunamis, or meteo-tsunamis, are long-period waves that possess tsunami charcteristics but are meteorological in origin, although they are not storm surges. The AA. investigate the coast of southern Britain (the English Channel
for bedrock-eroding rivers. In the Minas Passage (Bay of Fundy), Canada, the BristolChannel off Nash point, UK, and in the Straits of Messina, Italy, sonar data are collected and discussed. Holocene tidal currents have apparently been generally ineffective
it crosses a ridge compared with the borehole drilled where the road crosses the stream channel. Both borehole profiles indicate that the weathering zone extends to well below the stream channel in this upland catchment; hence weathering depth
[b1] School of Earth Sciences, Univ., Bristol, Royaume-Uni
Morphology of Red Creek, Wyoming, an arid-region anastomosing channel system
Aggradation is occuring in the main channel and on the floodplain throughout the study reach. Infilling of the main channel occurs primarily by lateral accretion, while the floodplain accretes vertically through deposition of overbank sediment from
the main channel and anabranches. Infilling of the main channel may cause avulsion of the main channel into an anabranch. The abandoned main channel segment may then fill completely or act as an anabranch. Because lateral migration of channels is inhibited
by the high cohesion of the silt and clay channel sediment, periodic avulsion is the primary form of lateral mobility in the system.
Controls on channel form and channel change in the Bell River, Eastern Cape, South Africa
Cape Province ; Channel geometry ; Fluvial erosion ; Fluvial hydrology ; Meander ; South Africa ; Stream
Channel instability has occurred in the Bell River in the form of meander cutoffs, incipient meander cutoffs and general channel instability. This is documented for a 40 year period and the causes examined. - (AJC)
A model of channel response in disturbed alluvial channels
The adjustment of channel geometry and phases of channel evolution are characterized by six process-oriented stages of morphologic development : premodified, constructed, degradation, threshold, aggradation, and restabilization. Downcutting and toe
removal during the degradation stage causes bank failure by mass wasking when the critical height and angle of the bank material is exceeded (threshold stage). Channel widening continues through the aggradation stage as the slough line develops
as an initial site of lower-bank stability. Alternate channel bars form during the restabilization stage and represent incipient meandering of the channel.
Channel adjustment and a test of rational regime theory in a proglacial braided stream
Alberta ; Braided channel ; Canada ; Channel geometry ; Discharge ; Grain size distribution ; Gravel ; Proglacial lake ; Sediment load ; Stream
The AA. analyze the historical trends in channel pattern and the contemporary downstream changes in channel geometry, grain size, and gradient in the gravel bed, proglacial Sunwapta River, Alberta. The rational equations incorporate the effect
of grain size and slope on channel width and the effect of width and grain size on channel slope. The regime equations are successful even though they were devised for single channel gravel streams. The results confirm the influence of grain size on channel
pattern thresholds and demonstrates, using spatial transitions in channel pattern, that channel pattern predictions based on stream power alone are inadequate.
Based on data from around 200 alluvial rivers in several countries, a systematic comparison of flow shear stress and stream power has been made between sand- and gravel-bed rivers. The formation of channel pattern can be regarded as the outcome
of sediment transport and channel bank constraints in an alluvial river. To overcome the difficulty of quantifying channel bank constraints, channel width/depth ratio and a dimensionless channel width index are used to reflect it indirectly.
River channel patterns are thought to form a morphological continuum. This continuum is two-dimensional, defined by plan features of which there are three (straight, meandering, branching), and structural levels of fluvial relief of which
there are also three (floodplain, flood channel, low-water channel). Combinations of these three categories define the diversity of patterns. The critical stream power values and hydrological regime together define the channel pattern, and analysis of the pattern