HYDRAULICS OF WEIR FLOW WITH SPECIAL REFERENCE TO SUBMERGENCE

Abstract

The. problem of weir flow is not as simple as it appears to be, The complex and rapidly varied nature of weir flow has given rise to many a fascinating study. While weirs are used in laboratories as a device for measurume;nt of flowing water, they servo many functions in the field. These are commonly incorporated in hydraulic structures for raising the water level besides being used for flow measurement in open channels. Evaluation of the hydraulic conditions of weir flow.,therofore_ deserves the careful attention of the hydraulic engineers associated with the design of these structures. Despite the fact that a vast amount of literature is available regarding their characteristics, one is at a loss to know the correct position for certain aspects and to evaluate the degree of accuracy of particular measurements. Submergence is a common phenomenon in weirs during high flows, and engineers have in the past hesitated to use submerged weirs duo to lock of design and porformance data, The amount of research work con-cerned with submergence is small related to its importance in hydraulic design. An attempt has been made$ heroin., to review the basic principles involved in the hydraulics of weir flow with special reference to submor- gence, Some of the important work on determination of a suitable dischar- for go equation/free flow as well as submerged conditions. has also been re-viewed. Also some of the available data has boon analysed to determine the effect of submergence on broad crested weirs. It has boon found that there is lack of adequate and reliable data for submergence of over 8O? and more work is required in this range.