STUDY OF HYDRAULIC CHARACTERISTICS OF A VEGETATED OPEN CHANNEL FLOW

In understanding hydraulic characteristics of open channel flow infested by vegetation, it
is necessary to study the characteristics of vegetation that occupies the channel.
Hypothetically, different vegetation will result in different characteristics. In this
experiment, Japanese grass, Cow grass and Pearl grass were used to understand the
relation of their presence towards open channel hydraulic characteristics.
Experiments were conducted inside a laboratory flume, with 5-m stretch of each grass
laid across the 10-m flume. Upon experiment, cross-sectional discharges, flow depths,
retardance coefficients and velocities were assessed to establish relationship between
vegetation and hydraulic characteristics.
By comparison of graphs of depth flow characteristic, velocity characteristic, and
discharge characteristic over the computed Manning’s n values, it can be concluded that
characteristic of Japanese grass, Cow grass and Pearl grass are found to behave in similar
pattern. The finding emphasis that, if there are an increase in channel discharge, there will
be an increase in the flow depth. Besides, as flow depth increases, velocity will also
increases. Eventually, when the velocity increases, manning’s retardance coefficient will
decreases and play minimal effect on impeding the channel flow.