Chapter 16

Question 1

hydrologic cycle

Answer 1

movement of water through Earth’s four spheres

Question 2

inflitration

Answer 2

precipitation soaks into the ground

Question 3

runoff

Answer 3

precipitation runs over the surface

Question 4

transpiration

Answer 4

water absorbed by plants and later transferred to the atmosphere

Question 5

evapotranspiration

Answer 5

as evaporation and transpiration both move water from the surface to the atmosphere

Question 6

Runoff starts as

Answer 6

sheet flow which develops into tiny channels called rills which forms gullies which form streams

Question 7

streams

Answer 7

any water that flows in a channel, regardless of size

Question 8

river

Answer 8

carries a substantial amount of water and has many tributaries

Question 9

Drainage Basin

Answer 9

stream drains an area of land

Question 10

Divide

Answer 10

the imaginary line separating one basin from another; sometimes visible as high ridge mountain region

Question 11

3 zones of river systems

Answer 11

Sediment production, sediment transportation, sediment deposition

Question 12

Sediment production

Answer 12

zone of a river where more sediment is derived
Located in the headwater region of a river system
Generated by: broken bedrock, bank erosion

Question 13

Sediment transport

Answer 13

transported in trunk streams; amount of sediment being eroded equals amount being deposited

Question 14

Sediment deposition

Answer 14

when a river reaches a large body of water, the energy decreases and river deposits sediments; usually only fine sediments are deposited in oceans

Question 15

laminar flow

Answer 15

water flowing in a nearly straight path

Question 16

turbulent flow

Answer 16

water moving quickly in an erratic fashion

Question 17

Factors affecting flow velocity

Answer 17

the slope, channel shape, roughness, discharge,

Question 18

The slope, or gradient of a stream

Answer 18

steeper gradient has more gravitational energy to drive channel flow

Question 19

Channel shape

Answer 19

most effective channel has a small wetted perimeter (area where the rive is in contact with the channel) compared to its cross-sectional area

Question 20

Channel size and roughness

Answer 20

increase in channel size will increase the cross-sectional area to wetted perimeter ration thus increasing efficiency; rough channels create turbulence and decreased velocity

Question 21

Discharge

Answer 21

volume of water flowing past a certain point in a given unit of time
when discharge increases; the width, depth, flow, and velocity increase

Question 22

longitudinal profile

Answer 22

cross-sectional view of a stream

most have a concave shape

Question 23

head or headwater

Answer 23

source of the stream

Question 24

mouth

Answer 24

the downstream point where the stream empties into a larger body of water
discharge, channel size, and velocity increases towards the mouth

Question 25

Quarrying

Answer 25

involves removing large blocks from the channel bed

Question 26

abrasion

Answer 26

scraping, bumping, and rubbing | erodes and polishes sediment s

Question 27

Potholes

Answer 27

when fast moving, swirling sediment in eddies abrades a hole

Question 28

Corrosion

Answer 28

rocks gradually dissolving in flowing water can occur in limestone bedrock channels

Question 29

Transport of sediment by streams

Answer 29

``` Dissolved load (in solution) Suspended load (in suspension) Bed load (rolling along the bottom) ```

Question 30

Dissolved load

Answer 30

most of the dissolved load is brought to a stream via groundwater NOT affect by stream velocity

Question 31

Suspended load

Answer 31

largest part of a stream is carried in suspension amount carried is controlled by stream velocity and settling velocity (speed at which a particle falls through a liquid) of sediments

Question 32

Bed load

Answer 32

Coarse sands, gravel, and boulders move along the stream bed by saltation (skipping or jumping) Less rapid and more localized than transport via suspended load

Question 33

Capacity

Answer 33

maximum load of solid particles a stream can carry | The greater the discharge the greater the capacity

Question 34

Competence

Answer 34

the maximum particle size a stream can transport | Streams with a faster velocity have a higher competence

Question 35

deposition of sediments by a stream

Answer 35

occurs when a stream's velocity is less than the settling velocity

Question 36

sorting

Answer 36

particles of the same size are deposited at the same time in this process Larger particles are settled out first

Question 37

alluvium

Answer 37

sediments deposited by streams

Question 38

Bedrock Channels

Answer 38

cut into the underlying strata

Question 39

meanders

Answer 39

streams transport suspended sediment in broad sweeping bends

Question 40

Cutbank

Answer 40

outside of a meander | zone of active erosion

Question 41

point bar

Answer 41

inside of a meander | zone of deposition

Question 42

cutoff oxbow lake

Answer 42

a meander that has been cut off from joined bends

Question 43

braided channel

Answer 43

is a network of converging and diverging channels that thread among numerous islands or gravel bars

Question 44

stream valley

Answer 44

channel and surrounding terrain that directs water to the stream alluvial channels have wide valley floors bedrock channels have V-shapped valleys

Question 45

base level

Answer 45

lowest point to which a stream can erode

Question 46

Ultimate base level

Answer 46

sea level

Question 47

Local or temporary base level

Answer 47

includes lakes, resistant layers of rock, and large rivers

Question 48

changing conditions causes readjustment of stream activities

Answer 48

raising base level= deposition | lowering base level= erosion

Question 49

graded stream

Answer 49

only transports sediment

Question 50

Deltas

Answer 50

when sediment-filled streams enter a large body of water

Question 51

water gap

Answer 51

notch where a river cuts through a ridge that lies in its path

Question 52

Antecedent stream

Answer 52

stream existed before the ridge was formed

Question 53

Superposed stream

Answer 53

Stream eroded into a preexisting structure

Question 54

headward erosion

Answer 54

stream that lengthen its coarse by extending the head of the valley upslope ; can result in stream piracy where the diversion of the drainage of one stream into another

Question 55

flood

Answer 55

occurs when the stream exceeds the capacity of its channel; most common and most destructive geological hazard

Question 56

Regional flood

Answer 56

seasonal flood that typically result from spring rains or rapid melting of snow

Question 57

Flash floods

Answer 57

occur with little or no warning in mountainous areas

Question 58

Ice-jam floods

Answer 58

ice forms in rivers creating dams that will break when temperatures rise

Question 59

Dam-Failure floods

Answer 59

Dams fail and release large amounts of water

Question 60

Flood Control

Answer 60

Artificial levees Channelization flood control dams non-structural approach