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Flashcards in Chapter 8: Dams Deck (105)
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1

The purpose of a dam is to 

impound (store) water for any of several reasons

2

The purpose of a dam is to impound (store) water for any of several reasons, e.g.,

flood control, water supply for humans or livestock, irrigation, energy generation, recreation, or pollution control. 

3

Water from rainfall or snowmelt naturally runs

downhill into a stream valley and then into larger streams or other bodies of water

4

The “watershed system” refers to 

the drainage process through which rainfall or snowmelt is collected into a particular stream valley during natural runoff (directed by gravity)

5

Water from rainfall or snowmelt naturally runs downhill into a stream valley and then into larger streams or other bodies of water. The “watershed system” refers to the drainage process through which rainfall or snowmelt is collected into a particular stream valley during natural runoff (directed by gravity).

Dams constructed across such a valley then impound the

runoff water and release it at a controlled rate. 

6

Dams constructed across such a valley then impound the runoff water and release it at a controlled rate. During periods of high runoff, ........................................ typically increases

water stored in the reservoir

7

Dams constructed across such a valley then impound the runoff water and release it at a controlled rate. During periods of high runoff, water stored in the reservoir typically increases, and .................................. may occur. 

overflow through a spillway

8

Dams constructed across such a valley then impound the runoff water and release it at a controlled rate. During periods of high runoff, water stored in the reservoir typically increases, and overflow through a spillway may occur. During periods of low runoff, reservoir levels usually 

decrease

9

During periods of low runoff, reservoir levels usually decrease. The owner can normally control the reservoir level to some degree by

adjusting the quantity of water released

10

During periods of low runoff, reservoir levels usually decrease. The owner can normally control the reservoir level to some degree by adjusting the quantity of water released. Downstream from the dam, the stream continues to 

exist

11

The owner can normally control the reservoir level to some degree by adjusting the quantity of water released. Downstream from the dam, the stream continues to exist, but because the quantity of water flowing is 

normally controlled, very high runoffs (floods) and very low runoffs (drought periods) are avoided.

12

Dams may either be 

human-built or result from natural phenomena

13

Dams may either be human-built or result from natural phenomena, such as 

landslides or glacial deposition

14

Dams may either be human-built or result from natural phenomena, such as landslides or glacial deposition. The majority of dams are

human structures normally constructed of earthfill, rocks or concrete

15

The majority of dams are human structures normally constructed of earthfill, rocks or concrete. Naturally occurring lakes may also be modified by

adding a spillway to allow for safe, efficient release of excess water from the resulting reservoir. 

16

Dam owners should be aware of: 

■ the different types of dams

■ essential components of a dam

■ how the components function, and

■ physical conditions likely to affect a dam. 

17

Human-built dams may be classified according to

the type of construction materials used,
the methods used in construction,
their slope or cross-section,
the way they resist the forces of the water pressure behind them,
the means of controlling seepage, and occasionally, their purpose. 

18

Components of dams

  1. foundation
  2. core or membrane
  3. shell
  4. transition filter
  5. internal drain
  6. toe drain

19

FOUNDATION

It consists of 

earth or rock 

20

FOUNDATION

It consists of either earth or rock and provides a support for 

the embankment 

21

. FOUNDATION

It consists of either earth or rock and provides a support for the embankment and resists 

both vertical and horizontal loads

22

. FOUNDATION

It consists of either earth or rock and provides a support for the embankment and resists both vertical and horizontal loads. It also resists 

under seepage on the flow of water beneath the dam.

23

CORE OR MEMBRANE

It holds back 

the free water of the dam reservoir

24

CORE OR MEMBRANE

It holds back the free water of the dam reservoir. It is located either at 

the centre or upstream from the centre of the dam.

25

CORE OR MEMBRANE

It holds back the free water of the dam reservoir. It is located either at the centre or upstream from the centre of the dam. In case of rock fill dams, the core is 

provided on the upstream face. 

26

SHELL

It provides

structural support for the core and distributes the load over the foundation.

27

SHELL

It provides structural support for the core and distributes the load over the foundation. The dams which are constructed of the same materials are called 

homogeneous dams. 

28

In core dams, a transition filter between the 

core and shell 

29

In core dams, a transition filter between the core and shell is generally provided to 

prevent the migration of the fine grained core materials into the pores of the coarse grained shell materials. 

30

An internal drain is provided on 

the downstream side of the dam