Drainage Basin, Flood Hydrograph, Water Budget

Question 1

what is a drainage basin

Answer 1

A local open system that draws an area with a river

Question 2

What separates a draingae basin

Answer 2

An imaginary line, usually a ridge of high land

Question 3

How does basin size affect a drainage basin

Answer 3

larger basin means it takes longer for the water to reach the river
Smaller basin means it takes less time for the water to react the river

Question 4

How does basin shape affect a drainage basin

Answer 4

A circular basin means all water is equidistant from the river meaning its overall lag time is shorter
A long drainage as in will mean some water will take much longer to meet the river meaning the lag time is longer

Question 5

How does basin slope and elevation affect a drainage basin

Answer 5

steeply sided basins means gravity assists the water when it is trying to get to the river
Gently sloped valleys tend to produce longer lag times

Question 6

How does Rock type affect a drainage basin

Answer 6

permeable rock allows water to go through them
impermeable rock does not allow water to go through them causing more surface runoff

Question 7

How does soil type affect a drainage basin

Answer 7

Sandy soils have high rates of infiltration
Clay soils have very small pore spaces allowing little water flow through

Question 8

what is water abstraction

Answer 8

it is the extraation of water from rivers and the ground

Question 9

What is base flow

Answer 9

water that reaches the channel largely through slow through flow and from permeable rock to the water table

Question 10

What is channel flow

Answer 10

The movement of water within the river channel
This is also called the rivers discharge

Question 11

What is groundwater flow

Answer 11

The deeper movement of water through underlying permeable rock bellow the water table

Question 12

what is infiltration

Answer 12

the downward movement of water into the soil surface

Question 13

what is percolation

Answer 13

The flow of water from the surface into the bedrock
This water usually stays underground for long periods of time

Question 14

What is surface runoff

Answer 14

The movement of water over the surface of the land
Usually when the ground is saturated or frozen

Question 15

What is relief rainfall

Answer 15

warm air rises up over mountains from the ocean
it cools and forms clouds causing it to rain

Question 16

What is conventional rain

Answer 16

occurs in the warmer months
The sun heats the rain causing the rain to rise and cool rapidly forming big clouds
these clouds produce heavy rain and thunder storms

Question 17

what is frontal rain

Answer 17

When a warm front meets a cold front
The cool air sinks beneath the warm air
The warm air condenses and forms rain

Question 18

How do humans affect the drainage basin

Answer 18

River Management
Deforestation
agriculture
urbanisation

Question 19

How does river management affect the drainage basin

Answer 19

construction of water stores slows the river
abstraction of water slows the river

Question 20

How does deforestation affect the drainage basin

Answer 20

reduces evapotranspiration
increases infiltration and surface runoff

Question 21

How does agriculture affect the drainage basin

Answer 21

compaction of soil increases surface runoff
ploughing increases infiltration by loosening the soil

Question 22

How does urbanisation affect the drainage basin

Answer 22

urban surfaces increase surface runoff
drains deliver water to rivers increasing flooding

Question 23

What is a flood hydrograph

Answer 23

a graph showing the discharge of a river following a particular event

Question 24

What is a flood hydrograph

Answer 24

a graph showing the discharge of a river following a particular event

Question 25

What a flood hydrographs useful for

Answer 25

plan for periods of flooding or drought

Question 26

What a flood hydrographs useful for

Answer 26

plan for periods of flooding or drought

Question 27

what is the water budget

Answer 27

the balance between the inputs and outputs of a drainage basin

Question 28

How is the water budget expressed

Answer 28

P=Q+E (+/- change in storage)

Question 29

What do the letters in the water budget equation stand for

Answer 29

P - precipitation
Q - discharge
E - evapotranspiration

Question 30

what is water surplus

Answer 30

when there is an excess amount of water available in the system

Question 31

What is deficiency

Answer 31

When there is a reduction of water available

Question 32

What is water recharge

Answer 32

After a period of deficiency precipitation will occur and replace the water lost in the soil

Question 33

What is field capacity

Answer 33

The maximum amount of water that soil can hold before it becomes saturated