Abstract
Irrigation canals and rivers require matching with the surrounding natural scenes and giving careful consideration to their water environments. Though many concrete blocks with stones are developed for this purpose, the hydraulic characteristics of those blocks are not well known. In this study, the roughness coefficients of concrete block with pebbles are examined by measuring water depths in a laboratory rectangular channel. The values of the Manning's roughness coefficient are estimated by numerical integration of the non-uniform flow equation. Changing discharge, channel slope, and water depth at the downstream end, 45 experimental runs are conducted. The estimated Manning's roughness coefficient has a good correlation with Reynolds number and ranges from 0.0135 to 0.0425.
