Field‐Measured Hydraulic Resistance Characteristics in Vegetation‐Infested Canals
Publication: Journal of Irrigation and Drainage Engineering
Volume 118, Issue 2
Abstract
Realistic estimates of hydraulic resistance are essential to the proper design and analysis of irrigation canal networks. Extensive field studies in Egypt provide data on the magnitude and variability of hydraulic resistance in earthen irrigation canals infested with aquatic weeds. Values of Manning resistance coefficient, n, were calculated from 280 measurements at selected cross sections in 23 stable canals with emergent ditch‐bank vegetation. The temporal sample mean of monthly values of n estimated within a year ranged from 0.017–0.062 for cross sections where five or more measurements were made. The temporal sample coefficient of variation ranged from 0.03–0.42. Dependence of n on flow regime (hydraulic depth and product of average velocity and hydraulic radius) was explored. Studies also were conducted on nine canals containing submerged vegetation. These studies included 312 sonar measurements of vegetation density as well as 156 measurements to estimate n at selected cross sections. Regression analysis revealed that variability in flow regime and in vegetation density contribute significantly to variability in n. Temporal mean of monthly values of vegetation density within a year ranged from 0.06–0.25, with temporal coefficient of variation between 0.17 and 0.92. Vegetation density at measured cross sections showed a clear seasonal pattern. The spatial mean and coefficient of variation in vegetation density along a canal were found to range monthly from 0.06–0.36 and from 0.18–0.76, respectively. Temporal mean values of n in canals with submerged vegetation ranged from 0.028–0.074, with temporal coefficient of variation between 0.13 and 0.57.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Bakry, M. F. (1989). “Effect of weeds on the flow characteristics in open channels,” thesis presented to Ain Shams University at Cairo, Egypt, in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
2.
Barnes, H. H., Jr. (1967). “Roughness characteristics of natural channels.” Water Supply Paper No. 1849, U.S. Geological Survey, U.S. Government Printing Office, Washington, D.C.
3.
Chow, V. T. (1959). Open‐channel hydraulics. McGraw‐Hill, New York, N.Y.
4.
French, R. H. (1985). Open‐channel hydraulics. McGraw‐Hill, New York, N.Y.
5.
Gwinn, W. R., and Ree, W. O. (1980). “Maintenance effects on the hydraulic properties of a vegetation‐lined channel.” Trans. ASAE, 23(3), 636–642.
6.
Henderson, F. M. (1966). Open‐channel flow. Macmillan, New York, N.Y.
7.
Kao, D. T. Y., and Barfield, B. J. (1978). “Predictions of flow hydraulics for vegetated channels.” Trans. ASAE, 21(3), 489–494.
8.
Khattab, A. F., and El‐Gharably, Z. (1987). “Problems of aquatic weeds in irrigation systems and methods of management.” Proc. of Sixth Afro‐Asian Regional Conf., International Commission on Irrigation and Drainage.
9.
Khattab, A. F., and El‐Gharably, Z. (1989). “Aquatic weeds and their effect on the hydraulic efficiency of irrigation and drainage systems in Egypt.” Proc. of Seventh Afro‐Asian Regional Conf., International Commission on Irrigation and Drainage.
10.
Kouwen, N. (1970). “Flow retardance in vegetated open channels,” thesis presented to the University of Waterloo, at Waterloo, Canada, in partial fulfillment of requirements for the degree of Doctor of Philosophy.
11.
Kouwen, N., and Unny, T. E. (1969). “Flow retardance in vegetated channels.” J. Irrig. and Drain. Div., ASCE, 95(2), 329–342.
12.
Kouwen, N., and Unny, T. E. (1973). “Flexible roughness in open channels.” J. Hydr. Div., ASCE, 99(5), 713–728.
13.
Kowobari, T. S., Rice, C. E., and Garton, I. E. (1972). “Effect of roughness elements on hydraulic resistance for overland flow.” Trans. ASAE, 15(5), 979–984.
14.
Lee, H.‐L., and Mays, L. W. (1986). “Hydraulic uncertainties in flood levee capacity.” J. Hydr. Engrg., ASCE, 112(10), 928–934.
15.
Li, R. M., and Shen, H. W. (1973). “Effect of tall vegetation on flow and sediment.” J. Hydr. Div., ASCE, 99(5), 793–814.
16.
Manz, D. H., and Westhoff, D. R. (1988). “Numerical analysis of the effects of aquatic weeds on the performance of irrigation conveyance systems.” Can. J. Civ. Engrg., 15, 1–13.
17.
Phelps, H. O. (1970). “The friction coefficient for shallow flows over a simulated turf surface.” Water Resour. Res., 6(4), 1220–1226
18.
Pitlo, R. H. (1986). “Towards a larger capacity of vegetated channels.” Proc. EWRS/AAB Seventh Symp. on Aquatic Weeds, 245–250.
19.
Ree, W. O., and Palmer, V. J. (1949). “Flow of water in channels protected by vegetative linings.” Tech. Bull. 967, U.S. Dept. of Agriculture, Washington, D.C.
20.
Salas, J. D., Delleur, J. W. Yevjevich, V., and Lane, W. L. (1980). Applied modeling of hydrologic time series. Water Resources Publications, Littleton, Colo.
21.
Thompson, G. T., and Roberson, J. A. (1976). “Theory of flow resistance for vegetated channels.” Trans. ASAE, 19(2), 288–293.
Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 118 • Issue 2 • March 1992
Pages: 256 - 274
Copyright
Copyright © 1992 ASCE.
History
Published online: Mar 1, 1992
Published in print: Mar 1992
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.