Manning's Roughness for Artificial Grasses

Roughnesses of three types of artificial grass are investigated. Artificial grass consists of a mattress that simulates the soil surface where groups of grass are fixed in longitudinal and radial rows. The experiments are conducted in rectangular and triangular laboratory flumes. The following conclusions can be drawn. The n-value was found to be dependent on the flow depth and on the Reynolds number at low range of depths. It was shown to be independent of the flow parameters at high range of depths. The constant roughness coefficient values for the higher discharges were n=0.032, n=0.027, and n=0.020 for the different artificial grasses. These n-values are in good agreement with the experimental results for real grass found in the literature. It may be concluded, therefore, that artificial grass will be a useful material when simulating grass in the hydraulic laboratory.