نتایج جستجو برای: sediment delivery ratio
تعداد نتایج: 731038 فیلتر نتایج به سال:
The vast marine deep biosphere consists of microbial habitats within sediment, pore waters, upper basaltic crust and the fluids that circulate throughout it. A wide range of temperature, pressure, pH, and electron donor and acceptor conditions exists-all of which can combine to affect carbon and nutrient cycling and result in gradients on spatial scales ranging from millimeters to kilometers. D...
Accumulations of sediment beneath the Antarctic Ice Sheet contain a range of physical and chemical proxies with the potential to document changes in ice sheet history and to identify and characterize life in subglacial settings. Retrieving subglacial sediments and sediment cores presents several unique challenges to existing technologies. This paper briefly reviews the history of sediment sampl...
Extended abstract 1- Introduction A bare surface on forest roads is created due to road construction. This surface is the main source of erosion and sediment yield to streams in forest areas. The increase of sediment in streams causes dramatic damage to the quality of water ecosystems and the life of aquatic organisms. Therefore, road engineers should pay attention not only to the cost of roa...
Sedimentation is one of the most important problems in harbors that results in considerable economic costs. Harbor planforms affects the flow pattern in the harbor basin and consequently, plays an important role in sediment transport and sedimentation. In the present study, a two dimensional depth-averaged hydrodynamic and sediment transport model has been developed to investigate the effect of...
[1] We evaluate three metrics representing the drivers of channel change downstream from dams. A balance between changes in sediment supply and transport capacity identifies conditions of sediment deficit or surplus. A Shields number represents the competence of postdam flows and the potential for incision under conditions of sediment deficit. A ratio of postdam to predam flood discharge provid...
The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, howev...
Arsenic (As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecor...
Evaluation of Sediment yield in watershed scale is considered so important for implementation of soil conservation, watershed management, environment, dam construction and water resource management. Using empirical model is one of the approaches of evaluating Sediment yield. This research in Kasilian watershed evaluates Sediment yield by using Geomorphology method and EPM model with Arc View GI...
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