水库RESERVOIRS

水库RESERVOIRS(中文6300字,英文3600字)
拦河筑一条像坝的障碍时，水就被拦蓄在障碍物的上游并形成水塘．通常称之为水库。
总而言之，被蓄集在水塘或湖泊里的水就称为水库．水库所蓄的水可有多种用途．水库根据其用途可分为以下几类：
①    蓄水水库。
②    防洪水库。
③    配水水库。
④    综合利用水库。
（1)    蓄水水库 
城市给水、灌洒供水或直接从河流中取水的水电工程或者溪流，在枯水期，也许不能满足用户的需要，在丰水期，由于洪水泛滥它们又可能无法发挥作用。蓄水水库在洪峰期能拦蓄多余的水量，而在枯水期需要水的时候又能平缓地把水放出。
顺便提一下。蓄水除为了今后的用水外。蓄洪还可减少水库下游的洪水灾害。因此．水库可以用于防洪或者还具有别的用途。前一种情况称为“防洪水库”，而后一种情况就称为“综合利用水库”。
(2)防洪水库
防洪水库一般称之为减洪水库．以拦蓄一部分洪水流量的方式降低洪峰，保护下游地区。为了达到这一目的，流进水库的水是全部排放，直到排水流量达到下游河槽的安全泄量为止。超过这个泄量的入流量就蓄存在水库里．待洪峰消退后．再逐渐排放，为迎战下一次洪水恢复蓄洪容积。
 防洪水库和蓄洪水库不同之处仅仅在于它需要一个大的泄洪能力，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.