A new method to identify the fluvial regimes used by spawning salmonids

2009 ◽  
Vol 66 (9) ◽  
pp. 1404-1408 ◽  
Author(s):  
Hamish J. Moir ◽  
Christopher N. Gibbins ◽  
John M. Buffington ◽  
John H. Webb ◽  
Chris Soulsby ◽  
...  
Keyword(s):  
Shear Stress ◽  
Spatial Patterns ◽  
Flow Regimes ◽  
River Networks ◽  
Spawning Habitat ◽  
Spawning Activity ◽  
Spawning Frequency ◽  
Fluvial Processes ◽  
Excess Shear Stress ◽  
Geomorphic Processes

Basin physiography and fluvial processes structure the availability of salmonid spawning habitat in river networks. However, methods that allow us to explicitly link hydrologic and geomorphic processes to spatial patterns of spawning at scales relevant to management are limited. Here we present a method that can be used to link the abundance of spawning salmonids to fluvial processes at the mesoscale. We show that the frequency of spawning activity at individual morphological units (riffles, pools, runs) is quantitatively related to a number of fluvial parameters. Of these, bankfull excess shear stress (τxs) was the best predictor of spawning frequency. Results suggest that τxs can be used to represent the fluvial regimes that spawning salmon are responsive to as well as to assess the likely impacts of altered flow regimes.

The Ecology and Management of Wood in World Rivers

2003 ◽  
Keyword(s):  
Spatial Patterns ◽  
General Framework ◽  
River System ◽  
Field Studies ◽  
Transport Processes ◽  
River Networks ◽  
Spatial And Temporal Patterns ◽  
History Of ◽  
World Rivers ◽  
Trapping Sites

<em>Abstract.</em>—A landscape perspective of wood in world rivers accounts for spatial and temporal patterns of sources of wood from streamside forests, processes of wood delivery to channels, transport of wood through river networks, and trapping sites of wood. Amounts of wood in a river system also depend on productivity of forests in source areas and decomposition rates. Collectively, these factors determine the amount and arrangement of individual pieces and accumulations of wood through a river network, which, in turn, affect ecological, geomorphic, social, and other features of rivers. Research to date deals with subsets of these components of wood in rivers, but there has been limited development of a general framework for wood in river networks. This chapter considers a framework for examining the arrangement of wood in river landscapes and how it may reflect the history of spatial patterns and timing of wood input and redistribution. Field studies provide examples of different spatial patterns and architectures of wood accumulations. Wood accumulations are shaped by input processes, trapping sites, and transport processes. Reaches in river networks may switch from wood patterns dominated by one set of controls to another because of gradual or abrupt input and redistribution. A framework for future studies and management includes interpretation of these different controls through time and over river networks.

Development of a Transient Mechanistic Two-Phase Flow Model for Wellbores

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 942-955 ◽  
Author(s):  
Mahdy Shirdel ◽  
Kamy Sepehrnoori
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Wall Shear ◽  
Two Fluid Model ◽  
Two Fluid

Summary A great deal of research has been focused on transient two-phase flow in wellbores. However, there is lack of a comprehensive two-fluid model in the literature. In this paper, we present an implementation of a pseudo-compositional, thermal, fully implicit, transient two-fluid model for two-phase flow in wellbores. In this model, we solve gas/liquid mass balance, gas/liquid momentum balance, and two-phase energy balance equations to obtain five primary variables: liquid velocity, gas velocity, pressure, holdup, and temperature. This simulator can be used as a stand-alone code or can be used in conjunction with a reservoir simulator to mimic wellbore/reservoir dynamic interactions. In our model, we consider stratified, bubbly, intermittent, and annular flow regimes using appropriate closure relations for interphase and wall-shear stress terms in the momentum equations. In our simulation, we found that the interphase and wall-shear stress terms for different flow regimes can significantly affect the model's results. In addition, the interphase momentum transfer terms mainly influence the holdup value. The outcome of this research leads to a more accurate simulation of multiphase flow in the wellbore and pipes, which can be applied to the surface facility design, well-performance optimization, and wellbore damage estimation.

Spatial patterns of soil organic carbon on hillslopes: Integrating geomorphic processes and the biological C cycle

Geoderma ◽  
2006 ◽  
Vol 130 (1-2) ◽  
pp. 47-65 ◽  
Author(s):  
Kyungsoo Yoo ◽  
Ronald Amundson ◽  
Arjun M. Heimsath ◽  
William E. Dietrich
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spatial Patterns ◽  
C Cycle ◽  
Geomorphic Processes

scholarly journals Spatial Patterns and Drivers of Nonperennial Flow Regimes in the Contiguous United States

2021 ◽  
Vol 48 (2) ◽  
Author(s):  
John C. Hammond ◽  
Margaret Zimmer ◽  
Margaret Shanafield ◽  
Kendra Kaiser ◽  
Sarah E. Godsey ◽  
...  
Keyword(s):  
United States ◽  
Spatial Patterns ◽  
Flow Regimes

DESIGN AND DEVELOPMENT OF FLOW BASED ELECTRO-RHEOLOGICAL DEVICES

1992 ◽  
Vol 06 (15n16) ◽  
pp. 2705-2730 ◽  
Author(s):  
D. A. BROOKS
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
Shear Rate ◽  
Basic Flow ◽  
Control Surface ◽  
Flow Data ◽  
Operational Systems ◽  
Flow Apparatus ◽  
Er Fluids ◽  
Excess Shear Stress

The foundations for the design of electro-rheological (ER) actuating devices that use Poiseuille flow are laid. Systems of measurement to assess ER fluids are described including a high pressure flow apparatus. This was used to examine alternative valve geometries and fluids. A method is shown for the reduction of basic flow data to excess shear stress and shear rate. Standard actuator arrangements are reviewed before the design of a flying control surface servomechanism is discussed. The evaluation of this validates the methods and indicates that the forces developed are within striking distance of those required for operational systems.

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