American Society of Civil Engineers


Flow over Gabion Weirs


by Hassan I. Mohamed, (Associate Professor, Civil Engineering Dept., Assiut Univ., Assiut 71516, Egypt. E-mail: hassanmohamed_2000@yahoo.com)

Journal of Irrigation and Drainage Engineering, Vol. 136, No. 8, August 2010, pp. 573-577, (doi:  http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0000215)

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Document type: Technical Note
Abstract: A conventional weir typically consists of an impermeable body constructed of concrete, since its primary functions are to heading up water and efficiently regulate flow. However, an impermeable body prevents the longitudinal movement of aquatic life and transportation of physical and chemical substances in water, eventually having a negative impact on the water environment. One of the advantages of gabions as a building material is that the motion of individual stones comprising the gabion is not of much concern. The wire mesh of the gabion basket serves to restrain any significant movement. Also, gabion weirs offer an alternative design that could be adopted for flash flood mitigation. In this study, a series of laboratory experiments was performed in order to investigate the flow over gabion weirs. For this purpose, two different gabion weir models were tested in two horizontal laboratory flumes of 10-m and 17-m length, 0.3-m width, and 0.3- and 0.5-m depth, respectively, for a wide range of discharge, upstream water depth, downstream water depth, weir height, weir length, and gabion filling gravel material size. The results of the gabion weir were compared with those of experiments carried out on solid weirs having the same dimension and it was found that there is a large deviation when the solid weirs equation is applied to gabion weirs (permeable weirs). So, using one of the existing solid weir flow formulas would lead to an erroneous calculated value. Multiple regression equations based on the dimensional analysis theory were developed for computing the discharge over gabion weirs for both free and submerged flow regimes. Also, equations were introduced for computing the discharge coefficient to be applied with the traditional solid weir equation.


ASCE Subject Headings:
Submerging
Coefficients
Weirs
Water flow
Free flow
Hydraulic structures

Author Keywords:
Weir
Free flow
Submerged flow
Gabion
Discharge coefficient