河流与洪水

河流与洪水

1.Artificial levees are built to prevent flooding. However, they often have negative effects. Which of the following is a negative effect of building levees?

a)Levees can indirectly lead to greater property damage during a flood by encouraging

increased building on a floodplain.

b)Levees decrease the rate of flow of water from tributaries into main streams.

c)High levees tend to increase peak discharge.

d)Levees decrease run off

e)All of the above are true.

人工堤坝建造以防止洪水。然而,他们经常有负面影响。下面哪个选项是建筑堤坝的负面影响?

堤坝可以间接导致更大的财产损失，在漫滩鼓励增加建筑。

堤坝下降的速率主要支流的水流入河流。

高堤坝会增加洪峰流量。

堤坝减少流失。

上面的都是真实的。

2.What is the probability of a 20-year flood occurring in any one year?

a) 2.0E-4

b)0.02

c)0.05

d)0.0020

e)0.0050

一个20年的洪水发生在一次的概率是多少?

3.The most important causes of river floods include what?

a)tidal waves

b)existence of floodplains

c)amounts and rates of precipitation and runoff

d)sedimentation

e)none of the above

最重要的河流洪水的原因包括什么?

潮汐波

存在的冲积平原

数量和降水和径流

沉积

以上都不是

4.In a meandering stream, where does erosion take place most rapidly?

a)in riffles

b)on the insides of bends

c)in pools

d)in central parts of the channels

e)on the outsides of bends

蜿蜒的小溪,在哪侵蚀发生得最快吗?

在急流

在弯曲的内部

在水池

中部地区的渠道

在弯曲的外部

5.What effect does a land-use change, from forest to agriculture, near a stream have on the stream?

a)increase in channel slope and decrease in the velocity of the water

b)increase in channel slope and velocity of the water

c)decrease in channel slope and increase in the velocity of the water

d)decrease in channel slope and velocity of the water

e)none of the above

什么影响土地利用变化,从森林到农业,小溪在小溪附近吗?

增加渠道边坡和水的速度下降

水通道的坡度和速度的增加

下降通道斜率和水的速度增加

水通道的坡度和速度下降

以上都不是

6.The time that elapses between the majority of rainfall and a flood’s peak is called what?

a)lag time

b)flow

c)gradient

d)delay

e)discharge rate

降雨和洪水之间间隔的大部分峰叫做什么？

滞后时间

流

梯度

延迟

放电率

7.Which of the following is the definition of a stream’s gradient?

a)the slope of the stream’s banks

b)the stream’s vertical drop per unit of horizontal distance

c)the surface of the stream’s cross-section

d)none of the above

e)all of the above

下面哪个是河流比降的定义?

河流堆积的斜率

河流的垂直下降每水平距离

河流的截面的表面

以上都不是

上面所有的

8.Which of the following composes the largest fraction of a stream’s load of sediment and dissolved materials?

a)bed load

b)dissolved load

c)discharge

d)suspended load

e)runoff

下面哪个组成的最大分数河流负载的沉积物和溶解的材料?

床上的负载