Unit 7 Flood Exercises (a)

1. Learn new words:

bank – берег according to – в соотвествии с чем-либо

to overflow – разливаться interval – промежуток, интервал

disaster– бедствие, несчастье recurrence interval – промежуток

fllod – наводнение, половодье, промежуток

разлив curve – кривая, диаграмма

beneficial result – положительный to measure – измерять

результат relatively – относительно

sediment – осадок level – уровень

to renew – обновлять, water surface – поверхность воды

восстанавливать to be expressed in быть

to fertilize – удобрять выраженым в чем-либо

to sink – просачиваться

soil – почва

to predict – предсказывать

magnitude – размер

frequency – частота

2. Translate the following word combinations:

the overbank discharge of а stream; on an average of every 1,2 years; as а disaster by man; on river floodplains; natural event; beneficial results; to deposit on the floodplain ; to renew and fertilize; to sink into the soil; to recharge the groundwater; а relatively high flow; to be measured by either gage height or discharge rate; indicate levels of the water surface; at measuring stations; the stream channel; in an average section; overflow of adjacent land; the usual channel boundaries; to reach flood stage; relative magnitudes of flood peaks; to be expressed in various terms; to include height above low water; height above flood stage; the direct or indirect result of precipitation; though the runoff; may be delayed or modified by the processes of freezing and thawing; flash flood; rapid increase of discharge in а river; to be marked by а precipitous rise in water level; to form а wall of water moving downstream; to be common in arid or in semiarid regions; to generate excessive runoff in an otherwise dry channel; may occur in humid regions; to concentrate the amount of runoff during an intense storm; to minimize the disastrous effects of floods; to predict their magnitude and frequency; by listing flood; to discharge according to magnitude; from this data; the time interval; can be expected; to be called the recurrence interval; each flood discharge.

Text (a)

Read the text «Flood»:

Flood is the overbank discharge of а stream. Most streams overflow their banks on an average of every 1,2 years. Although looked on as а disaster by man because he builds homes and industries on river floodplains, а flood is а natural event that often has beneficial results. The water carries sediment, which it deposits on the floodplain to renew and fertilize it; the water sinks into the soil to recharge the groundwater. А flood is а relatively high flow as measured by either gage height or discharge rate. Gage readings indicate levels of the water surface at measuring stations. Whenever the stream channel in an average section is overtaxed, causing overflow of adjacent land definitely outside the usual channel boundaries, the stream is said to have reached flood stage. Relative magnitudes of flood peaks may be expressed in various terms, including either height above low water, height above flood stage, or the corresponding rate of discharge.

Flood flows are normally the direct or indirect result of precipitation, even though the runoff may be delayed or modified by the processes of freezing and thawing, surface inequalities or indentations, interception on vegetal cover or through infiltration, -underground flow, and temporary storage in or release from reservoirs through either natural or artificial means of detention and regulation.

Flash flood is а sudden, rapid increase of discharge in а river. А flash flood is marked by а precipitous rise in water level that forms а wall of water moving downstream. Flash floods are common in arid or in semiarid regions, where an intense local гainstorm often generates excessive runoff in an otherwise dry channel. Flash floods may occur in humid regions if conditions in the watershed are such as to suddenly concentrate the amount of runoff during an intense storm.

One way to minimize the disastrous effects of floods is to predict their magnitude and frequency. А flood frequency analysis is made by listing flood discharges according to magnitude.

From this data the time interval at which such discharges can be expected is calculated. It is called the recurrence interval. Each flood discharge is then plotted against its recurrence interval, and the points form the frequency curve. These curves are used by engineers in building bridges and roads.