Proceedings of the Advanced Seminar on one-dimensional, open-channel Flow and transport modeling

Water-Resources Investigations Report 89-4061




If several limiting assumptions are valid, flow in a waterbody can be represented by one-dimensional equations of unsteady open-channel flow. The equations can be expressed in a number of forms of varying complexity, depending upon the choice of dependent variables used in their formulation and on possible additional limiting assumptions which allow various terms to be excluded. The assumptions are related to the physical characteristics of water and water flow, characteristics of the flow channel, and the effects of boundary friction and turbulence. With the assumptions, unsteady open-channel flow can be described by two dependent variables, either flow discharge and water surface elevation or flow velocity and cross-sectional area. These variables are expressed as a function of distance and time at a given cross section. The equations are derived from the principles of conservation of mass and momentum. Additional variables may be included to account for wind effects , the Coriolis effect, overbank storage, and other influences. Equations are formulated for unsteady gradually varied flow, steady gradually varied flow, steady uniform flow (the Manning equation), and other variations. More rudimentary continuity-based equations, such as the kinematic wave equation and storage-routing equations, are inherently more empirical and considerable caution must be exercised in their use. Models employing the full dynamic equations for simulating unsteady open-channel flow should be used whenever possible. (See also W90-10652) (Tappert-PTT)

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USGS Numbered Series
Proceedings of the Advanced Seminar on one-dimensional, open-channel Flow and transport modeling
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Water-Resources Investigations Report
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U.S. Geological Survey,
vii, 99 p. :ill. ;28 cm.