نتایج جستجو برای: alluvial river
تعداد نتایج: 86183 فیلتر نتایج به سال:
A contaminated site related to a former coke factory, located in the alluvial plain of the Meuse River near Liège was investigated to characterize the nature and extend of underground contamination. The major objective of the investigation was to evaluate whether an interaction exists, at the level of this particular site, between groundwater and surface water, despite the existence of river em...
The processes of sediment transport, scour, and deposition in an alluvial channel are extremely complex. Theoretical developments of sediment transport functions for different flow and sediment conditions are based on assumptions of different degrees of complexity [1]. Some of the simplified assumptions are based on idealized laboratory conditions that may not be true for the much more complica...
River-response and Terrace Agradation in the Mediterranean Iberian Peninsula during Historical Times
Mediterranean fluvial environments have responded sensitively to past changes in climate, physiographic conditions and human activity. Chronosequences of river terraces and alluvial deposits were established using morphologic, sedimentological and pedologic criteria, Cand Pb-dating techniques, historical data and pottery fragments. The objective of this study addresses the fluvial dynamic of se...
This article presents a three-level approach to the analysis of downstream hydraulic geometry. First, empirical concepts based on field observations of ‘poised’ conditions in irrigation canals are examined. Second, theoretical developments have been made possible by combining basic relationships for the description of flow and sediment transport in alluvial rivers. Third, a relatively new conce...
Introduction The Potomac Formation is a heterogeneous assemblage of ancient river deposits consisting chiefly of unconsolidated and poorly consolidated sands, silts, clays, and small amounts of gravel, along with localized zones of diamictons of uncertain origin. It is the dominant geologic unit in the City of Alexandria. It crops out or is close to the surface everywhere west of Old Town and D...
While most global productivity is driven by modern photosynthesis, river ecosystems are supplied by locally fixed and imported carbon that spans a range of ages. Alluvial aquifers of gravel-bedded river floodplains present a conundrum: despite no possibility for photosynthesis in groundwater and extreme paucity of labile organic carbon, they support diverse and abundant large-bodied consumers (...
An intelligent method based on adaptive neuro-fuzzy inference system (ANFIS) for identifying Manning’s roughness coefficients in modeling of alluvial river is presented. The procedure for selecting values of Manning n is subjective and requires judgment and skill which are developed primarily through experience. During practical applications, researchers often find that a correct choice of the ...
In this study the advantages and importance of a numerical model to predict and monitor the processes governing hydraulic changes alluvial fan river is discussed. For this reason and because of the importance of flow velocity and shear stresses resulting from the erosion of the river, A two-dimensional numerical model to simulate the CCHE2D river changes ranging from Roodan River is used. In th...
High N fertilizer and flooding irrigation applied to rice on anthropogenic-alluvial soil often result in N leaching and low recovery of applied fertilizer N from the rice fields in Ningxia irrigation region in the upper reaches of the Yellow River, which threatens ecological environment, food security, and sustainable agricultural development. This paper reported the regulating N application fo...
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