1-D versus 2-D entropy velocity law for water discharge assessment in a rough ditch

Water discharge assessment in open channel flow is one of the most crucial issues for hydraulic engineers in the fields of water resource management, river dynamics, ecohydraulics, irrigation, and hydraulic structure design, among others. Recent studies state that the entropy velocity law allows expeditive methodology for discharge estimation and rating curve development due to the simple mathematical formulation and implementation. Many works have been developed based on the one-dimensional (1-D) formulation of the entropy velocity profile, supporting measurements in the lab and the field for rating curve assessment, but in recent years, the two-dimensional (2-D) formulation was proposed and applied in studies of regular ditch flow, showing good performance. The present work deals with a comparison between the 1-D and 2-D approaches in order to give a general framework of threats and opportunities related to the robust operational application of such laws. The analysis was carried out on a laboratory ditch with regular roughness, under controlled boundary conditions, and in different stages, generating an exhaustive dashboard for better appraisal of the approaches.