|
  Water
from snow and rainfall will find its way into stream and rivers
and eventually into the sea. After severe storms, or heavy
snow or rain over a number of days, the water level in rivers
can rise dramatically. Sometimes, the water flows over riverbanks
or walls causing flooding of farmland, property, and in the
worst cases, loss of life.
 A
reservoir
can be used to control the amount of water flowing in a river
after heavy rain. The water level in the reservoir is kept
low during the rainier periods of the year. When heavy rain
occurs, it is stopped by the dam and held back in the reservoir.
When the reservoir gets too full, the floodwater can be passed
downstream
over a spillway.
Sometimes, floodgates
are used on top of spillways, and they can be fully or partly
opened to control the amount of water let out into the river
downstream.
|
