Spatial And Temporal Change

Question 1

What is the water budget?

Answer 1

Balance between inputs and outputs in a system, affects how much water stored in a system

Question 2

What is water surplus?

Answer 2

When precipitation > evaporation. Occurs in wet seasons, allows for groundwater to recharge

Question 3

What is water deficit?

Answer 3

When evaporation > precipitation. Drier seasons, groundwater stores depleted

Question 4

What is the water balance formula?

Answer 4

Precipitation = Run-off + evapotranspiration +/- change in storage

Question 5

What is the river regime?

Answer 5

The variability in discharge throughout the course of a year in response to precipitation, evapotranspiration, and drainage basin characteristics

Question 6

What influences on the river regime are there?

Answer 6

Precipitation
Evapotranspiration
Drainage basin characteristics and land use
Geology
Tributaries

Question 7

What is utilisation?

Answer 7

Plants using water stores

Question 8

What is the recharging period?

Answer 8

Groundwater stores refilling after a water deficit

Question 9

What is the water balance equation?

Answer 9

Precipitation = evaporation + transpiration + river flow +/- storage

Question 10

What is river discharge measured in?

Answer 10

Cumecs (cubic meters per second)

Question 11

What are characteristics of a flashy hydrograph?

Answer 11

Short lag time (hour of peak discharge - hour of peak rainfall). Steep rising limb. Falling limb falls slower than rising limb because throughflow and groundwater flow reach the river, adding to discharge

Question 12

What are characteristics of a subdued hydrograph?

Answer 12

long lag time, gradual rising limb

Question 13

What physical factors affect hydrographs and discharge?

Answer 13

Shape and size of drainage basin
Slope of angle surrounding land
Intensity of rainfall
Soil/rock type
Vegetation cover
Antecedent conditions

Question 14

What human factors affect hydrographs and discharge?

Answer 14

Deforestation
Agriculture
River flood management
Water abstraction rates

Question 15

How do storm events affect water cycle?

Answer 15

Flash floods
Increased temps cause more evaporation, causing more water in atmosphere, so stronger rainstorms
As vapour condenses, heat energy given off, increasing strength of storm

Question 16

How do seasonal changes affect water cycle?

Answer 16

Wet seasons - precipitation > evaporation so water surplus. Groundwater stores fall causing more surface runoff
Dry seasons - evapotranspiration > precipitation, groundwater stores depleted and humans and plants use water so water deficit

Question 17

Effects of localised deforestation on the water cycle

Answer 17

Evapotranspiration lower
Less interception so increased overland flow and throughflow
River discharge higher, and chance of flood higher

Question 18

Effects of extensive deforestation on water cycle

Answer 18

Most water leaves area in channel flow rather than being recycled through evapotranspiration.
Less water vapour in atmosphere, so less precipitation, so lower river levels

Question 19

What is soil drainage and what effects does it have on water cycle?

Answer 19

• When water table is high, tubes drain water from soil improving aeration and this improves soil structure
• increases throughflow and surface layer can dry out

Question 20

What is water abstraction and how can it affect water cycle?

Answer 20

• Groundwater abstraction removes from ground source. Most water used for irrigation or drinking
• Can lead to rivers drying up, damage to wetland ecosystems, sinking water tables, empty wells

Question 21

Effects of water abstraction in SE England chalk bedrock.

Answer 21

• water table fell allowing saline water to contaminate freshwater aquifers
• During 19th and 20th century, due to industrialisation the water table was lowered 88 meters below sea level
• This causes a threat to buildings as water table rises again so soil become moist and unstable.

Question 22

How does deforestation affect the water cycle?

Answer 22

• Less transpiration due to less trees, which reduces water vapour, so less rainfall and drier climates
• More throughfall as less interception, and more overland flow leading to a flashy hydrograph

Question 23

What are the short term effects of deforestation?

Answer 23

• Reduced transpiration so less water vapour in atmosphere
• Decreased rainfall/hotter drier climates
• Increased overland flow
• Less infilitration into aquifers

Question 24

What are the long term effects of deforestation?

Answer 24

• Disruption of regional rainfall
• Drought and desertification
• Increased carbon emissions
• Altered climate patterns regionally/globally

Question 25

Effects of deforestation in the Mekong Basin?

Answer 25

- Deforested catchments have seen a 15-30% decline in infiltration rates, and an increase in overland flow - Disrupted rainfall, so farmers reliant on consistent precipitation have further water stress

Question 26

Effects of soil drainage on the Aral Sea?

Answer 26

- It was the 4th largest lake in the world - In 1960s, it's 2 main rivers were diverted for irrigation to grow cotton - Now it only covers 10% of what it used to and was replaced by a salty, arid desert

Question 27

Describe the river catchment of the River Tweed

Answer 27

- Horseshoe shaped basin, mainly sedimentary rock (large groundwater sotres) - Upper course has many trees so high interception rates - Many dammed tributaries by beavers

Question 28

Describe the river management of the River Tweed

Answer 28

Do nothing - flooding of wetlands allowed to decrease river discharge downstream Willow Soiling - Willow's Eco-Shutters have stopped the erosion of the bank after 18 month Channelisation - downstream to increase river capacity

Question 29

When and where were floods of the River Tweed

Answer 29

1956 - the Till floodplain completely flooded 2014 - flood embankment breached and roads in Merlindale completely underwater

Question 30

What land uses along the Tweed are there?

Answer 30

- Mostly for farming and crops, especially upper course which is prone to flooding - 80% of land is used for agriculture - Some water is pumped to Edinburgh as there is a sustainable supply, which decreases discharge