Water and carbon cycle 4 - Variations in runoff and the water cycle

Question 1

What is river discharge

Answer 1

The volume of water that flows in a river per second

Question 2

What is river discharge measured in

Answer 2

cubic metres per second

Question 3

What is runoff

Answer 3

Water flowing on the surface of the land

Question 4

What happens when there is high levels of run off

Answer 4

Increases the discharge of a river because more water makes it into the rivet, increasing its volume

Question 5

What are hydrographs

Answer 5

Graphs of river. discharge over time

Question 6

What do they show

Answer 6

How the volume of water flowing at a certain point in a river changes over time

Question 7

what do flood / storm hydrographs show

Answer 7

River discharge around the type of a storm event

Question 8

What time frequency do flood / storm hydrographs show

Answer 8

a relatively short time period (normally days or hours)

Question 9

What are the 4 parts of a hydrograph?

Answer 9

1) Peak discharge
2) Lag time
3) Rising limb
4) Falling limb

Question 10

What’s peak discharge

Answer 10

The highest point on the graph, when the river discharge is at its greatest

Question 11

What is lag time

Answer 11

The delay between peak rainfall and peak discharge

Question 12

Why does this delay happen

Answer 12

It takes time for rainwater to flow into the river.

Question 13

What does a shorter lag time mean

Answer 13

Increases peak discharge because more water reaches the river during a shorter period of time

Question 14

What is rising limb?

Answer 14

The part of the graph up to peak discharge. river discharge increases as rainwater flows into the river

Question 15

What is falling limb

Answer 15

Part of the graph after peak discharge

Question 16

Why is discharge decreasing

Answer 16

Less water is flowing into the river

Question 17

What does a shallow falling limb show

Answer 17

Water is flowing in from stores long after it’s stopped raining

Question 18

What kind of hydrograph does a basin with rapid run off and not much storage give

Answer 18

A hydrograph with a short lag time and high peak discharge

Question 19

What is this known as

Answer 19

Flashy hydrograph

Question 20

What does a flashy hydrograph look like

Answer 20

Its steep, roughly symmetrical rising and falling limbs

Question 21

What 4 factors does the amount of runoff and shape of hydrograph depend on

Answer 21

• Size of drainage basin
• Shape of drainage basin
• Ground steepness
• Rock and soil type

Question 22

What happens when it is a larger drainage basin

Answer 22

They catch more precipitation so have a higher peak discharge

Question 23

What happens when its a smaller drainage basin

Answer 23

Have shorter lag times because precipitation has less distance to travel, so reaches the channel more quickly

Question 24

What are circular basins hydrograph like

Answer 24

More likely to have a flashy hydrographs compared to long, narrow basins

Question 25

Why is this

Answer 25

All points on the watershed are roughly the same distance from the point of discharge measurement

Question 26

What happens the ground is downhill

Answer 26

Water flows more quickly in steep-sided basins shortening lag time

Question 27

What does this mean

Answer 27

Lots of water will reach the measuring point at the same time

Question 28

How does this affect the run off

Answer 28

Water has less time to infiltrate the soil so run off is higher

Question 29

What is the hydrograph like in impermeable rocks and soils

Answer 29

As they don't store water or let water infiltrate it increases surface runoff. Peak discharge also increases as more water reaches the river in a shorter period

Question 30

What are these 2 natural processes

Answer 30

- Storms and precipitation - Seasonal changes and vegetation

Question 31

What are hydrographs, runoff and the water cycle affected by

Answer 31

Natural processes

Question 32

What influence do intense storms have

Answer 32

They generate more precipitation and greater peak discharge than light rain showers

Question 33

What happens if the input of water is larger

Answer 33

It causes flows, like runoff and stores

Question 34

What can increase run off

Answer 34

Some flows may not be able to occur rapidly enough for the size of the input

Question 35

What varies with seasons

Answer 35

The size of inputs, flows and stores

Question 36

What happens during the winter

Answer 36

temp drops below 0 causing water to freeze. This reduces the size of flows through drainage basins, while the store of frozen water grows

Question 37

What happens as the temperature increases again

Answer 37

Flows through drainage basins and outputs are much larger as ice melts

Question 38

How do plants show seasonal variation?

Answer 38

Vegetation intercepts precipitation and slows its movement to the river channel

Question 39

When's interception highest

Answer 39

When there's lots of vegetation and deciduous trees have their leaves

Question 40

What happens when there is more vegetation in the drainage basin

Answer 40

The more water is lost through transpiration and evaporation before it reaches the river channel, reducing runoff and peak discharge

Question 41

What affects the size of stores and size and speed of flows

Answer 41

human activities

Question 42

What are these 3 human activities

Answer 42

1) Farming practices 2) Land use change 3) Water abstraction

Question 43

What is a key part of the water cycle

Answer 43

Infiltration

Question 44

What happens when rain can't infiltrate

Answer 44

It runs off

Question 45

What 4 ways does farming practices affect infiltration.

Answer 45

1) Ploughing breaks up the surface so more water can infiltrate, reducing the amount of run off 2) Crops increase infiltration and interception. compared to bare ground, reducing run off. Evapotranspiration also increases, increasing rainfall 3) Livestock, like cattle, trample and compact the soil, decreasing infiltration and increasing run off 4) Irrigation can increase runoff if some of the water can't infiltrate. Groundwater or river levels can fall if water is extracted for irrigation

Question 46

What is irrigation

Answer 46

Artificially watering land

Question 47

How does deforestation affect this?

Answer 47

reduces the amount of water that's intercepted by vegetation, increasing the amount that reaches the surface. In forested areas dead plant material on the forest floor helps to hold the water, allowing it to infiltrate the soil rather than run off. When forest cover is removed the amount of infiltration that can take place decreases

Question 48

What does the construction of new buildings and roads create

Answer 48

An impermeable layer over land, preventing infiltration. This increases runoff, resulting in water passing through the system much more rapidly and making flooding more likely

Question 49

When is more water abstracted

Answer 49

To meet demand in areas with high population density

Question 50

What does water abstraction do

Answer 50

Reduces the amount of water in stores such as lakes, rivers, reservoirs and groundwater

Question 51

What happens during dry Seasons

Answer 51

Even more water is abstracted from stores for consumption and irrigation so stores are depleted further