Showing papers on "Stream power published in 1982"

Sediment Transport and Unit Stream Power Function

Abstract: Basic fluid mechanics and turbulence theories are applied to show that suspended sediment concentration at a given depth of an open channel flow is a function of the turbulence energy production rate at that depth. Depth-averaged suspended sediment concentration can be obtained by integrating a function of the turbulence energy production rate over the depth of flow which in turn is a function of unit stream power. Total sediment concentration can also be expressed as a function of unit stream power following the foresaid and a procedure similar to that proposed by Einstein. Comparisons of seven total load equations indicate that equations derived from the concept that the rate of sediment transport should be related to the rate of energy dissipation of the flow are more accurate than other equations for both laboratory flumes and natural rivers.

Stream-grade variation and riparian- forest ecology along Passage Creek, Virginia.

Abstract: U.S. Geological Survey, National Center, M.S. 461, Reston, VA 22092 Hupp, CLIFF R. (U.S. Geol. Surv., National Center, Mail Stop 461, Reston, Virginia 22092). Stream grade changes and riparian-forest ecology along Passage Creek, Virginia. Bull. Torrey Bot. Club 109: 488-499. 1982.-Passage Creek, in northwestern Virginia, flows on relatively nonresistant shales, then cuts through a gorge underlain by resistant sandstone. In the gorge, the stream gradient steepens, the size of bed material increases, a braided channel forms, and riparian-forest composition and growth form changes relative to areas outside the gorge. Effects of flooding are intensified within the gorge and revealed in the pattern and deformation of streamside vegetation. Increased stream gradient within the gorge provides for high stream power and coarse sediment deposition relative to the flood plain outside the gorge. A more diverse upland forest grows on the flood plain in the gorge. The riparian forest in the gorge may be an example of a nonequilibrium forest, resulting from periodic disturbance by destructive floods. Recognition of vegetation patterns resulting from such disturbances may be useful in detection of potential flooding.

Mathematical Model for Erodible Channels

Abstract: A mathematical model for erodible channels is formulated, developed and tested with field data. A significant feature of the model is its ability to account for changes in both channel width and channel-bed profile of aggrading and degrading streams. Since changes in channel width and channel-bed elevation are closely interrelated, this model represents an improvement in this direction. This model employs the techniQues for water and sediment routing; an additional condition based upon the concept of minimum stream power is used as the width predictor. Analysis using this model shows that the total stream power of a reach is reduced if the widths at all cross-sections are so adjusted as to reduce the variation in energy gradients at these sections. When this model is applied, a varied flow will eventually develop into a uniform flow for which the stream power is an eventual minimum.

Fluvial Hydraulics of Deltas and Alluvial Fans

Abstract: Delta formation and its associated steam channel hydraulics have been studied using data obtained in a large laboratory flume The findings for deltas are generally applicable to alluvial fans Delta or fan shape is directly related to the pattern of stream flow, its loci, and mode of deposition In response to a change in water discharge, sediment feeding rate or base level, stream channel adjustments on the delta are characterized by the formation of a single channel or multiple distributary channels The changes in channel pattern are associated with large changes in channel width and stream power expenditure Stream channel changes are related to the stream’s tendency to seek equal power expenditure along the channel; they also provide delicate adjustments in velocity and sediment load to favor restoration of channel’s equilibrium