Artificial roughness standard for open channels

Abstract

In the formulas in present use the resistance coefficient has been considered constant for a particular type of material in a particular state of upkeep. The resistance coefficient, however, is not a constant for a given channel but varies with both velocity and depth. From the nature of these formulas in present use it may be seen that the variable influence of viscosity is not taken into consideration. Because of the need for more accurately determining the discharges in open channels a standard for roughness for open channels such as that which exists for pipes is desirable. The problem of developing a reproducible standard for roughness in open channels has previously received very little systematic study. Although several investigations have been made, each was made with a different type of roughness. This study was conducted for the purpose of determining whether an artificial roughness standard could be established for a channel with a boundary so rough that the viscous effects were negligible. The equation was established and is applicable over at least a fourfold variation in d/a and nearly a twofold variation in the resistance coefficient.

A soft hydrological monitoring approach for comparing runoff on a network of small poorly gauged catchments

“…First, the estimated roughness for non‐aquatic vegetation that grows in ephemeral streams is very different from that of aquatic vegetation. Second, many studies have been performed using artificial vegetation implanted in artificial flume (Einstein and Banks, 1950; Robinson and Albertson, 1952; Sayer, 1961; Taylor and Brooks, 1962; Kowobari et al , 1972; Petryck and Bosmamajian, 1975; Kao and Barfield, 1982), whereas others were performed using natural conditions, with natural bed and vegetation types, but adapted to specific research topics (Emmet, 1970; Temple, 1980; Kao and Barfield, 1982; Temple, 1983; Rhee et al , 2008). The results show that Manning's roughness coefficients determined in these studies provide large discharge overestimates.…”

Analysis of Manning coefficient for small-depth flows on vegetated beds

“…Einstein and Banks (1950) developed an equation for sticks' density. Also, Robinson and Albertson (1952) tested artificial standard roughness; similarly, Sayer (1961) determined the flow delay for various roughnesses. Kowobari et al (1972) not only analysed the roughness coefficients, but also developed a flow resistance model.…”

Changing Velocity Distribution Over the Length of a Dune

“…In this connection the studies of Johnson (1944 ), Powell (1946Powell ( , 1950, Robinson and Albertson (1952), Basha (1961 ), Sayre and Albertson (1963), Oloughlin and Shastri ( 1963), Singhal (1969), Ranga Raju and Garde ( 1970), and Garde and Kaka ( 1977) can be cited as examples. In these studies primarily two aspects of the flow were studied.…”