Determination of Manning's Roughness Coefficient for Dhaleshwari River Using Hec-Ras

The Dhaleshwari River is a distributary of Jamuna River and flows past Dhaka city into the Meghna estuary. The flow through the Dhaleshwari River is influenced by roughness characteristic of the channel material. Manning's n is used extensively around the world to predict the degree of roughness in channels. This paper presents a hydrodynamic HEC-RAS 1D model to estimate Manning's n for the Dhaleshwari River. The system requires data including cross-section, water level and discharge measurements. After a model is developed, it undergoes a calibration and a validation phase. Finally the calibrated and validated model result for Manning's n can be used for scenario analysis.