Abstract
Reservoir sedimentation management has become an important topic to
large dams in the United States due to their historical design, current
age, and increased environmental regulation. Less attention has been
paid to small dams in remote mountains even though they are facing a
more urgent sedimentation problem due to their relatively small storage.
This study aimed to explore the relation between reservoir operations
and sediment erosion in a small dam’s backwater zone to seek potential
alternative solutions to flushing and excavation. Mindful timing and
magnitude adjustment of water transfer, water diverted by tunnels,
through a reservoir was hypothesized to strategically redistribute
sediment erosion for sites with water transfer/diversion facilities in
the main channel. It was found that sediment erosion was increased by
over 100% by turning the water transfer to the maximum level which is
12 times higher than mean annual discharge. With stage drawdown, the
increment of sediment erosion was further increased by over 50%
compared with water transfer only scenarios. Upstream inflow with
occurrence from 5% to 25% was found to be the optimal hydrologic
condition for water transfer. These results indicated that water
transfer is a promising strategy to redistribute deposited sediment
downstream of it with appropriate stage drawdown.