Flooding - Drainage Basins

Question 1

what is the basic role of streams and rivers within the Earth system?

Answer 1

drain water off the landscape and transport sediments

Question 2

how does flood happen?

Answer 2

when stream overflow its banks owing to the sheer amount of water flowing from the landscape and into the stream

Question 3

why is there a tendency of large number of people and buildings to be at risk of flooding?

Answer 3

1.) humans concentrate their settlements along waterways
2.) relatively frequent nature of flooding

Question 4

these tend to cause increased development in area that previously had been avoided due to frequent flooding

Answer 4

use of engineering controls

Question 4

these tend to cause increased development in area that previously had been avoided due to frequent flooding

Answer 4

use of engineering controls

Question 5

formula for discharge

Answer 5

volume (ft^3) / time (s)

Question 6

how do you get the volume of a discharge?

Answer 6

multiply cross sectional area of the stream to its average velocity

Question 7

how do you get cross sectional area of a stream?

Answer 7

length x average depth

Question 8

how do you get average velocity of a stream?

Answer 8

using an empty plastic bottle, timer, and a measuring tape

Question 9

the velocity of a stream is greater along the _______ because it has ________ friction

Answer 9

center ; lesser

Question 10

described as the volume of water moving through a channel over a given time interval

Answer 10

stream discharge

Question 11

a process where water flows through stream channels

Answer 11

runoff

Question 12

precipitation reaching the land surface moves downslope in thin sheets

Answer 12

overland flow

Question 13

these allows water to return back to the atmosphere

Answer 13

evaporation and plant transpiration

Question 14

discharge of groundwater into the surface environment

Answer 14

groundwater baseflow

Question 15

the volume of water moving through a channel

Answer 15

stream discharge

Question 16

t or f: frequency of flood increases due to climate change

Answer 16

t

Question 17

provide information about a river or a stream by simply plotting the discharge versus time

Answer 17

stream hydrographs

Question 18

stream hydrographs is a function of:

Answer 18

discharge and time

Question 19

the amount of time for water to move across the landscape and into channels

Answer 19

lag time

Question 20

lag time is a function of

Answer 20

distance between where the rain is falling to the particular channel where discharge is being measured

Question 21

this allows streams in man areas to have a continuous input of groundwater at some minimum level

Answer 21

baseflow conditions

Question 22

keeps streams from going dry between rain events, thus is critical in maintaining the health of stream ecosystems

Answer 22

groundwater baseflow into streams

Question 23

___________ allows more water to infiltrate to the water table which causes the water table in _______to be higher than the ________, thereby forcing groundwater to flow into streams, this is referred to as ___________-

Answer 23

high precipitation ; humid regions; stream channels; gaining streams

Question 24

are a result of less deep infiltration in arid areas resulting in water table that is below the level of most stream channels

Answer 24

losing streams

Question 25

useful tool in analyzing how stream discharge changes over time

Answer 25

stream hydrographs

Question 26

a network of stream channels where merging tributaries form progressively larger streams

Answer 26

drainage system

Question 27

smaller of any two merging channels

Answer 27

tributary

Question 28

larger stream that serves as the principal channel within a drainage system

Answer 28

river

Question 29

the upper portion of the drainage system

Answer 29

headwaters

Question 30

found in the lower part of the system where a river empties into an ocean, lake or another river

Answer 30

mouth

Question 31

t or f: headwater streams are generally small and relatively fast moving

Answer 31

t

Question 32

headwater streams occupy ______ ; the mouth have gently flowing river that occupy ________

Answer 32

narrow valleys ; wider valleys

Question 33

individual systems are separated by one another by a

Answer 33

drainage divide

Question 34

a drainage divide is a

Answer 34

topographic high or crest in the landscape ; ridge

Question 35

useful for mapping what hydrogeologist call the drainage basin

Answer 35

drainage divides

Question 36

represents the land area that collects water for an individual stream or river

Answer 36

watershed or drainage basin

Question 37

t or f: rainfall can cause flooding in one basin but have yet no impact on stream discharge in adjoining basin

Answer 37

t

Question 38

t or f: as streams go downhill, they merge and form progressively larger streams and rivers

Answer 38

t

Question 39

the high ground separating different drainage networks

Answer 39

drainage basin

Question 40

top ten largest rivers in the world based on discharge

Answer 40

1. Amazon 2. Congo 3. Ganges 4. Yangtze 5. Orinoco 6. Parana 7. Yenisey 8. Mississippi 9. Lena 10. Mekong

Question 41

what continent has the most number of largest rivers?

Answer 41

Asia

Question 42

an area on a map outlined by a divide is known as

Answer 42

drainage basin

Question 43

t or f: a drainage basin can be large or small

Answer 43

t

Question 44

two major river basin in mindanao:

Answer 44

1.) Mindanao River Basin 2.) Agusan River Basin

Question 45

provinces that the mindanao river basin covers

Answer 45

Bukidnon, Maguindanao, North Cotabato, South Cotabato, Sultan Kudarat

Question 46

regions that the mindanao river basin covers

Answer 46

X , XII, ARMM

Question 47

cities that mindanao river basin covers

Answer 47

Cotabato City, Korondal

Question 48

total land area of mindanao river basin

Answer 48

21,503 km^2

Question 49

second largest river basin in the Philippines

Answer 49

Mindanao River Basin

Question 50

largest river basin in the Philippines

Answer 50

Cagayan River Basin

Question 51

total land area of Cagayan River Basin

Answer 51

27,493.49 km^2

Question 52

a stream flowing away from the mainstream due to sediment influx

Answer 52

distributary

Question 53

any smaller stream that feed larges streams within a drainage basin

Answer 53

tributaries

Question 54

a method of classifying or ordering the hierarchy of natural channels

Answer 54

Strahler Stream Order

Question 55

stream order is regionally controlled by

Answer 55

topography and geology

Question 56

t or f: a high number of strahler stream order means the stream is larger

Answer 56

t

Question 57

reflects the downstream trade off between discharge and slope in setting transport capacity

Answer 57

Stream Longitudinal Profile

Question 58

the ability of a stream to move sediment and incise rocks

Answer 58

sediment transport capacity

Question 59

t or f: steep gradient and changes in slope results in high flow velocity thus, high transport capacity

Answer 59

t

Question 60

variables of a stream longitudinal profile

Answer 60

elevation and river length

Question 61

the level below which a river or stream cannot incise or erode

Answer 61

base level

Question 62

the level where the velocity and eroding power of the water is temporarily lost, it lies in topographic laws that are relatively still elevated

Answer 62

local base level

Question 63

examples of local base levels

Answer 63

marshes, swamps, lake, dam, watefalls

Question 64

this is the ultimate (absolute) base level for most streams

Answer 64

global sea level

Question 65

quantity of average sea level rise in the Philippines

Answer 65

3 to 4 mm/yr

Question 66

quantity of average sea level rise in Davao

Answer 66

2 to 3 mm/yr

Question 67

t or f: absolute sea level is zero meters above sea level

Answer 67

t

Question 68

this is defined as total stream channel length divided by the area of the drainage basin

Answer 68

drainage density

Question 69

a stream longitudinal profile can be generated in GIS through:

Answer 69

DEM and line feature

Question 70

what does a small break value in delineating drainage system in GIS mean?

Answer 70

high channel length, more stream features delineated

Question 71

drainage density is approximately equals the inverse of the

Answer 71

source basin length

Question 72

________ tends to be highly dissected and thus have a high drainage density

Answer 72

steep terrains

Question 73

_________ tends to be less well dissected, with substantial hillslope convexities and low drainage density

Answer 73

gentle terrain

Question 74

examples of steep and gentle terrains

Answer 74

steep : flanks of volcanoes gentle: flood areas/ plains

Question 75

what forms braided and anastomosing streams?

Answer 75

high sediment influx than surface runoff