Comparative Analysis of Hydraulic Roughness Coefficient at Purna River Sites

In all engineering studies conducted on rivers and in designing structures intersecting these rivers, such as bridges, diversion weirs, intake ports, etc. where knowing the depth and velocity of the flow is required as well, the exact determination of the roughness coefficient is needed. The manning's n is a coefficient which represents the Roughness or Friction applied to the flow by the channel. Hydraulic roughness is highly variable parameter which depends upon the number of factors such as surface roughness, vegetation, channel irregularities, channel alignment, channel slope etc. The present paper discusses the predictability of different equations for determining the hydraulic roughness coefficient at the Garudeshwar and Gopalkheda site stations on Purna river in Gujarat. Statistical parameters such as mean percentage error (MPE), root mean square error (RMSE), discrepancy ratio (DR) and inequality coefficient (U) have been computed for evaluating the performance of selected formulas. Graphical comparisons are done to demonstrate the performance and variations for different data sets. Predicted values are compared with those observed by using Manning's Equation, empirical relations such as: Limerinous, Strickler, Meyer?Peter and Muller and using Cowan's tables. Little variation in results is observed for Manning equation at Garudeshwar and Chow equation at Gopalkheda station. Citation: P. R. Prajapati, DGGEC, Surat; Prof. B. M. Vadher ,DR. S S &S G GEC, Surat; Dr. S. M. Yadav ,SVNIT, Surat. "Comparative Analysis of Hydraulic Roughness Coefficient at Purna River Sites." Global Research and Development Journal For Engineering : 574 - 579.