Estimation of energy dissipation in step-pool reaches of mountain river
- a field investigation
Abstract
The bed of the step-pool rivers is adapted to the flow conditions in
terms of the topographic position and the steep slope of the path in
such a way to dissipate the water energy, along the river. The beds of
these rivers is sinusoidal like the meander rivers. However, as the
river banks are mostly rocky in mountainous areas and the erosion in
these areas is less, the bed fluctuation of these reaches is mainly
vertical. When the water flow streams from the step crest into the pool,
most of the water energy dissipates. In addition to the height
difference, other factors contribute to the energy dissipation in the
step pool reaches. The present study examines the energy dissipation by
determining its effective factors, including step height (H), step
length (L), hydraulic radius (R), sediment material diameter (d84),
velocity in the step (V), etc. by field measurements in three reaches of
mountain rivers. In the same vein, an equation is provided to estimate
energy dissipation in the step pool reaches, by considering measurable
effective parameters.