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1

Groundwater is

is an important and significant part of the hydrologic cycle. Yet, it remains a mystery to many people

2

Groundwater is an important and significant part of the hydrologic cycle. Yet, it remains a mystery to many people. Because we

cannot see it directly, groundwater defies our experience of the land surface as a solid, rigid boundary marking the top of the earth

3

In the vast majority of intermontane basins - ........................-

the areas where groundwater exists in greatest quantity

4

. In the vast majority of intermontane basins—the areas where groundwater exists in greatest quantity—groundwater

fills small, often microscopic pores between the grains of sediment

5

Groundwater may occur in

tiny fractures and fissures of rocks hidden below the loose, or unconsolidated, surface sediments

6

Groundwater may occur in tiny fractures and fissures of rocks hidden below the loose, or unconsolidated, surface sediments. To the naked eye

soils and rocks may appear next to impenetrable

7

To the naked eye, soils and rocks may appear next to impenetrable. But most such materials are, in fact, a

microscopic universe full of empty spaces that can be occupied by water

8

. But most such materials are, in fact, a microscopic universe full of empty spaces that can be occupied by water. When such water completely fills the void space of sediment pores or rock fractures, the pores or fractures are said to be

saturated

9

When such water completely fills the void space of sediment pores or rock fractures, the pores or fractures are said to be saturated. In all but truly ........................areas, the ground just beneath the land surface is ..........................: water occupies only part of the pore space

swampy
aerated

10

The boundary between ................................ and .............................. is referred to as the water table.

vadose zone water (unsaturated)
groundwater

11

The zone above the water table is referred to as the

“unsaturated zone” or “vadose zone

12

The term “soil” describes

only the first three to six feet below the land surface that is exposed to weathering plant root growth, etc.

13

In cold to moderate, humid climates, the vadose zone is commonly

identical to the soil layer

14

In cold to moderate, humid climates, the vadose zone is commonly identical to the soil layer—that is, the water table is

less than 6 feet from the land surface

15

In Mediterranean and semi-arid climates, it is not uncommon to have a ............... that is ............................

vadose zone that is several tens of feet thick.

16

In Mediterranean and semi-arid climates, it is not uncommon to have a vadose zone that is several tens of feet thick. In some areas, this zone may even be

be several hundred feet thick.

17

While the vadose zone is not a resource from which we can obtain water, it is an important

storage area, pathway, and potential barrier for pathogens, nutrients, or contaminants traveling within the water.

18

To understand the occurrence of groundwater at a given site, one must understand the

local geology

19

Geologists usually investigate local geology by studying

the type and age of the various sediment and rock layers

20

Geologists usually investigate local geology by studying the type and age of the various sediment and rock layers. That information also provides

important clues about the characteristics of the groundwater system in an area.

21

A geologic formation from which significant amounts of groundwater can be pumped for

domestic, municipal, or agricultural uses is known as an aquifer

22

A geologic formation from which significant amounts of groundwater can be pumped for domestic, municipal, or agricultural uses is known as an aquifer. The term is relative: it means that a geologic unit

yields water relative to surrounding materials

23

A geologic formation from which significant amounts of groundwater can be pumped for domestic, municipal, or agricultural uses is known as an aquifer. The term is relative: it means that a geologic unit yields water relative to surrounding materials, but

does not indicate that a specific amount of groundwater can be pumped.

24

A small intermontane-valley aquifer yields

significantly more water than its surrounding hard rock (bedrock) formations.

25

Aquifers sometimes are ...................... separated by......................... that permit...................................

vertically
geologic formations
little or no water to flow.

26

The formation that acts as water barrier is called

aquitard

27

The formation that acts as water barrier is called aquitard if it is

much less permeable than a nearby aquifer but still permits flow (e.g., sandy clay).

28

aquiclude

If the water barrier is almost impermeable (e.g., clay) and forms a more or less formidable flow barrier between multiple levels of aquifers

29

Aquifers can be of two major types

unconfined or confined

30

In an unconfined aquifer, there is

no overlying aquitard or aquiclude