The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
M A Jinrong - One of the best experts on this subject based on the ideXlab platform.
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a system of Fluvial Process analysis based on gis
Journal of China Hydrology, 2009Co-Authors: M A JinrongAbstract:In order to analyze Fluvial Process,a lot of historical data are needed.Because of large number of the historical data and many formats,the operational need were summarized in 4 aspects of space and attribute data management,river section,sedimentation,and slope risk analysis.Based on 3D Active X(ArcEngine),a Fluvial Process system was developed by using longitude-latitude structure design method and COM component technology.
Guoan Yu - One of the best experts on this subject based on the ideXlab platform.
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river network evolution and Fluvial Process responses to human activity in a hyper arid environment case of the tarim river in northwest china
Catena, 2016Co-Authors: Guoan Yu, Markus Disse, He Qing Huang, Yang Yu, Zhiwei LiAbstract:Abstract The Tarim River, the longest dryland river in an extremely arid region of China, has undergone ever-increasing human impacts over recent centuries (particularly since the late 1950s during which time large-scale land reclamation in the basin has taken place). Historical literature/maps, gauged hydrological data and satellite images were analyzed to examine how the river network evolution in the basin and the Fluvial morphology of the main stem of the Tarim River have responded to human influences. The results demonstrate that human activity (inhabitation, land reclamation and water resources development) in the basin have had significant impacts on the Tarim River, causing major changes in runoff and sediment transport, river network composition and river morphology (especially planform patterns). Gauged hydrological data from the past five decades presented an obvious reduction in runoff and sediment load in the Tarim River, even though the runoff from source tributaries exhibited a gentle increase. The annual occurrence of low flow events showed a significant increase, and the occurrence of moderate-high flow events followed a gentle decrease. The river network system has disintegrated from a historically ‘(quasi-) centripetal’ system with nine tributaries into several isolated river systems, which have mainly developed since the 20th century. Currently, only four tributaries flow into the main stem river, which is dominated by braided channel patterns in the upper reaches and meandering (typically with distorted bends) patterns in the middle reaches. The braided reach was in aggradation and in high lateral mobility. The mean width and braiding intensity of the braided reach followed a gentle decrease mainly due to the reclamation of river flood plains to farmlands and embankments. The sinuosity index of the current Tarim River channel is distinctively lower than the indexes of the old channels that were abandoned decades or centuries ago, even though the sinuosity index of the meandering channel followed a gentle increase in recent decades due to the increased occurrence of low flow events. Human activity has changed the natural Fluvial Processes and morphology of the Tarim River and has reduced the diversity of the river network system.
Ellen Wohl - One of the best experts on this subject based on the ideXlab platform.
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an evaluation of stream characteristics in glacial versus Fluvial Process domains in the colorado front range
Geomorphology, 2015Co-Authors: Bridget Livers, Ellen WohlAbstract:Abstract Many of the conceptual models developed for river networks emphasize progressive downstream trends in morphology and Processes. Such models can fall short in describing the longitudinal variability associated with low-order streams. A more thorough understanding of the influence of local variability of Process and form in low-order stream channels is required to remotely and accurately predict channel geometry characteristics for management purposes, and in this context designating Process domains is useful. We define Process domains with respect to glacial versus Fluvial valleys and lateral confinement of valley segments. We evaluated local variability of Process domains in the Colorado Front Range by systematically following streams, categorizing them into stream morphologic type and Process domain, and evaluating a number of channel geometry characteristics. We evaluated 111 stream reaches for significant differences in channel geometry among stream types and Process domains, location and clustering of stream types on a slope–drainage area ( S – A ) plot and downstream hydraulic geometry relationships. Although individual channel geometry variables differed significantly between individual stream types in glacial and Fluvial Process domains, no single channel geometry variable consistently differentiated all stream types between Process domains. Hypothetical S – A boundaries between bedrock- and alluvial-bed channels proposed in previous studies did not reliably divide bedrock and alluvial reaches for our study sites. Although downstream hydraulic geometry relationships are well-defined using all reaches in the study area, reaches in glacial valleys display much more variability in channel geometry characteristics than reaches in Fluvial valleys, less pronounced downstream hydraulic geometry relationships, and greater scatter of reaches on an S – A plot. Local spatial variability associated with Process domains at the reach scale (10 1 –10 3 m) overrides progressive downstream relationships in low-order mountain streams of the Colorado Front Range.
David R Montgomery - One of the best experts on this subject based on the ideXlab platform.
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the legacy of pleistocene glaciation and the organization of lowland alluvial Process domains in the puget sound region
Geomorphology, 2011Co-Authors: Brian D Collins, David R MontgomeryAbstract:article i nfo Alluvial rivers of the eastern Puget lowland, a landscape shaped by scour and fill from the Cordilleran ice sheet, continue to respond to patterns of deposition and scour by the last-glacial-age ice sheet 18,000 years after deglaciation. Topography revealed by valley cross sections created from high resolution LIDAR digital elevation models shows that rivers are aggrading in valleys eroded by subglacial runoff and degrading in valleys incised by rivers post-glaciation. Slope-area analysis of river profiles shows that profile concavity varies systematically between river segments in the two valley contexts. Concavity indices (θ) in mountain headwaters (0.3b θb0.9) compare to those of many world rivers (0.2b θb1.0), but in the lowlands these indices differ between valleys created by subglacial Fluvial erosion (5b θb45) and post-glacially incised river valleys that grade to base levels set by these relict glacial valleys or by post-glacial sea levels (1b θb7). Dramatic differences in river pattern, landforms, and dynamics occur in valleys having contrasting (aggrading vs. degrading) and incomplete responses to Pleistocene glaciation, creating discrete valley-scale hetero- geneities in Fluvial Process domains along and between rivers. These results point to the importance of valley- scale organization of alluvial Process domains along and between rivers having profiles remaining in disequilibrium from Pleistocene glaciation. They also point to the potential usefulness of slope-area analysis of longitudinal profiles in distinguishing among different river valley Process domains in lowland alluvial landscapes.
Zhiwei Li - One of the best experts on this subject based on the ideXlab platform.
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river network evolution and Fluvial Process responses to human activity in a hyper arid environment case of the tarim river in northwest china
Catena, 2016Co-Authors: Guoan Yu, Markus Disse, He Qing Huang, Yang Yu, Zhiwei LiAbstract:Abstract The Tarim River, the longest dryland river in an extremely arid region of China, has undergone ever-increasing human impacts over recent centuries (particularly since the late 1950s during which time large-scale land reclamation in the basin has taken place). Historical literature/maps, gauged hydrological data and satellite images were analyzed to examine how the river network evolution in the basin and the Fluvial morphology of the main stem of the Tarim River have responded to human influences. The results demonstrate that human activity (inhabitation, land reclamation and water resources development) in the basin have had significant impacts on the Tarim River, causing major changes in runoff and sediment transport, river network composition and river morphology (especially planform patterns). Gauged hydrological data from the past five decades presented an obvious reduction in runoff and sediment load in the Tarim River, even though the runoff from source tributaries exhibited a gentle increase. The annual occurrence of low flow events showed a significant increase, and the occurrence of moderate-high flow events followed a gentle decrease. The river network system has disintegrated from a historically ‘(quasi-) centripetal’ system with nine tributaries into several isolated river systems, which have mainly developed since the 20th century. Currently, only four tributaries flow into the main stem river, which is dominated by braided channel patterns in the upper reaches and meandering (typically with distorted bends) patterns in the middle reaches. The braided reach was in aggradation and in high lateral mobility. The mean width and braiding intensity of the braided reach followed a gentle decrease mainly due to the reclamation of river flood plains to farmlands and embankments. The sinuosity index of the current Tarim River channel is distinctively lower than the indexes of the old channels that were abandoned decades or centuries ago, even though the sinuosity index of the meandering channel followed a gentle increase in recent decades due to the increased occurrence of low flow events. Human activity has changed the natural Fluvial Processes and morphology of the Tarim River and has reduced the diversity of the river network system.