12. Find the translation of the following terms and memorize their meaning.

crest gate	bridge	a keyway
storage	emergency bulkhead	entrance
temporary	lift gate	generally
movable gate	radial gate	ordinarily
flashboard	rolling gate	bell mouth
a panel	bear-trap gate	installation
a pin	drum gate	to install
a hoist	outlet works	projection
a stop log	to be jammed	a slot
needle	a sluiceway	a valve
to span	inlet sluice	smooth
a pier	considerable	circular
a predetermined level	rectangular	cavity

13. Read the text to get the gist of it. Answer the following question.

What are the main types of gates?

Text B Gates and Outlet Works

Additional storage of water above the spillway crest can be obtained by the installation of temporary or movable gates. There are several types of gates.

The usual flashboard gates consist of wooden panels, supported by vertical pins placed on the crest of the spillway. Such installations are temporary. They are removed when the water surface reaches in the reservoir a predetermined level.

Stop logs consist of horizontal timbers spanning the space between piers. The logs may be raised by hand or with a hoist. There is usually much leakage between the logs and considerable time may be required for removing the logs if they become jammed in the slots. Stop logs are ordinarily used for small installations.

Needles consist of timbers with their lower ends resting in a keyway on the spillway crest and their upper ends supported by a bridge. Needles are somewhat easier to remove than stop logs but are quite difficult to place in flowing water. Consequently they are used mainly for emergency bulkheads where they need not be replaced until flow has stopped. There are some other types of gates, such as vertical lift gates, radial gates, rolling gates, bear-trap gates, drum gates.

Outlet works must be provided in order that water can be drawn from the reservoir when it is required. This water may be discharged into the channel below the dam or may be transported in pipes or canals to some distant point. All outlet works must be provided with gates or valves in order to regulate discharges of water.

A sluiceway is a pipe or tunnel that passes directly through a dam or the hillside at one end of the dam and discharges into the stream below. The outlets of most dams consist of one or more sluiceways, with their inlet being at about minimum reservoir level. If the quantity of discharged water is to vary considerably, then several sluiceways are required.

Sluiceways may be circular or rectangular. The interior should be smooth and without projections or cavities. Considerable attention should be given to the design of the sluiceway entrance. A bell mouth entrance is generally used.