水庫RESERVOIRS

水庫RESERVOIRS(中文6300字,英文3600字)
攔河筑一條像壩的障礙時，水就被攔蓄在障礙物的上游并形成水塘．通常稱之為水庫。
總而言之，被蓄集在水塘或湖泊里的水就稱為水庫．水庫所蓄的水可有多種用途．水庫根據其用途可分為以下幾類：
①    蓄水水庫。
②    防洪水庫。
③    配水水庫。
④    綜合利用水庫。
（1)    蓄水水庫 
城市給水、灌灑供水或直接從河流中取水的水電工程或者溪流，在枯水期，也許不能滿足用戶的需要，在豐水期，由于洪水泛濫它們又可能無法發揮作用。蓄水水庫在洪峰期能攔蓄多余的水量，而在枯水期需要水的時候又能平緩地把水放出。
順便提一下。蓄水除為了今后的用水外。蓄洪還可減少水庫下游的洪水災害。因此．水庫可以用于防洪或者還具有別的用途。前一種情況稱為“防洪水庫”，而后一種情況就稱為“綜合利用水庫”。
(2)防洪水庫
防洪水庫一般稱之為減洪水庫．以攔蓄一部分洪水流量的方式降低洪峰，保護下游地區。為了達到這一目的，流進水庫的水是全部排放，直到排水流量達到下游河槽的安全泄量為止。超過這個泄量的入流量就蓄存在水庫里．待洪峰消退后．再逐漸排放，為迎戰下一次洪水恢復蓄洪容積。
 防洪水庫和蓄洪水庫不同之處僅僅在于它需要一個大的泄洪能力，以便在洪水之前或之后可以迅速向下游放水。

1.RESERVOIRS
When a barrier is constructed across some river in the form of a dam, water gets stored up on the upstream side of the barrier, forming a pool of water, generally called a reservoir.
Broadly speaking, any water collected in a pool or a lake may be termed as a reservoir. The water stored in reservoir may be used for various purposes. Depending upon the purposes served, the reservoirs may be classified as follows:
①    Storage or Conservation Reservoirs.
②    Flood Control Reservoirs.
③    Distribution Reservoirs.
④    Multipurpose reservoirs.
(1)  Storage or Conservation Reservoirs.    
A city water supply, irrigation water supply or a hydroelectric project drawing water directly from a river or a stream may fail to satisfy the consumers’ demands during extremely low flows, while during high flows; it may become difficult to carry out their operation due to devastating floods. A storage or a conservation reservoir can retain such excess supplies during periods of peak flows and can release them gradually during low flows as and when the need arise.