Volume 18, Numéro 2, Pages 43-55

Theoretical Approach To Stage-discharge Relationship For Circular Sharp-crested Weir

Authors : Amara Lyes . Achour Bachir .


A novel theoretical approach for the flow discharge relationship in circular sharp crested weir is developed in the present paper. Based on the application of the energy equation applied between a section taken in the approach channel and the weir under critical flow conditions, a general stage-discharge relationship is obtained taking account width contraction effect and kinetic energy in the approaching channel. A correction function is introduced to take into account the simplifying assumptions assumed in the theory such as the non-consideration of viscous effects, the curvature of the streamlines due to the contraction of the weir and the surface tension. Derivation of the discharge coefficient expression for classical stage-discharge equation is also given. In order to check the proposed model, verification with laboratory measurement data available in literature are made. Results show a very good agreement between predicted and actual discharge.


Circular weir ; Stage-discharge equation ; Discharge coefficient ; Approach velocity