In hydraulic engineering, the bottom outlet is the closable opening for emptying the reservoir contents (the usable space) of a dam or other type of reservoir down to the “lowest lowering target”. It can be regulated with a closing device such as a gate valve . In the case of a pure retention basin , which is only used to accumulate water to protect against flooding, the bottom outlet allows the stream to flow freely through the dam when the water level is normal.
The bottom outlet is mostly to be found at the bottom of the dam at the foot of the dam or dam and mostly ends in a stilling basin to reduce the high speed of the water. Emptying a dam normally takes several weeks or months , depending on the size of the reservoir and the limited capacity of the water below the dam. With some dams, the dead space remains after emptying, which can no longer be emptied. The bottom outlet is - besides the flood relief - often the only extraction device in a dam. It is always the deepest extraction facility.
In addition to the bottom outlet, a dam can also have other extraction options:
- Raw water extraction (for drinking water supply )
- Service water withdrawal
- Turbine line
- Reserve outlet
In addition, every dam must be equipped with a flood relief .
- What is a bottom outlet and a service outlet? (PDF; 175 kB), accessed on June 9, 2013
- AWEL: Office for Waste, Water, Energy and Air: Notice board: detention basin on Jonen Bach to protect Affoltern am Albis
- Bretscheider, Lecher Schmidt: Taschenbuch der Wasserwirtschaft , 6th edition, Verlag Paul Parey, Hamburg and Berlin, 1982, page 630
- Bretscheider, Lecher Schmidt: Taschenbuch der Wasserwirtschaft , 6th edition, Verlag Paul Parey, Hamburg and Berlin, 1982, page 613
- DIN 4048 Hydraulic Engineering, Terms, Dams, Part 1 , January 1987