Roughness Coefficient of Open Channel Carrying Garbage and Water Hyacinth

Abstract

This experimental study was aimed at determining the Manning's roughness coefficient of canals carrying floating garbage and water hyacinth. The study was conducted in a flow circulated rectangular flume of 0.6×16×0.75 m in Coastal Hydraulic Laboratory, Department of Water Resources Engineering, Chulalongkorn University. Floating garbage was modeled using weighed plastic and wood in this experiment with seventy-five sets. In addition, water hyacinth was modeled in this experiment with fifty sets. The experiments were performed with the ranges of flow depths of 0.45 m to 0.60 m and 7.87 liter/s to 17.4 liter/s, respectively. The study results indicated that the garbage and water hyacinth increased the Manning’s n roughness coefficient about 20% and 17%, respectively. The results also shown that the increase of length of both garbage and water hyacinth increased the Manning’s n roughness coefficient. Moreover, the increase of submerge depth of both garbage and water hyacinth increased the Manning’s n roughness coefficient.