Water systems

Question 1

Earths water budget

Answer 1

• 70% of Earths surface is covered by water
• 2.6% is freshwater
• 97% is saltwater

Question 2

supply of fresh water

Answer 2

• 68.7% is water in polar ice caps
• 30.1% is in ground water
• 0.3% is in lakes, rivers and swamps

Question 3

turnover time

Answer 3

the time it takes for a molecule of water to enter and leave part of the system

Question 4

hydrological cycle

Answer 4

• consists of variety of storages and lows of water between the various storages

Question 5

transfers

Answer 5

• advection
• flooding
• surface runoff
• infiltration
• streams flows and currents

Question 6

transformations

Answer 6

• evapotransporation
• condensation
• freezing

Question 7

storages include

Answer 7

• oceans
• soil
• groundwater
• lakes
• rivers and streams
• atmosphere
• glaciers and icecaps

Question 8

human impact on the hydrological cycle

Answer 8

withdrawals - for domestic use, irrigation and industry
discharges - by adding pollutants to water from agriculture, fertiliser and sugar
- diverting rivers - diverted away to avoid flood damage

Question 9

ocean current

Answer 9

movement of water both vertically and horizontally

Question 10

surface currents

Answer 10

• upper 400m of the ocean
• moved by wind
• earths rotation deflects them and increases circular movement

Question 11

deep water currents

Answer 11

• makes up 90% of ocean currents
• warm water holds less salt than cold water so is less dense and rises
• cold water holds more salt so is dense and sinks

Question 12

cold currents

Answer 12

run from poles to the equator

Question 13

warm currents

Answer 13

run from equator to the poles

Question 14

ocean currents affects on local climate

Answer 14

• warm gulf stream moderates climate of north western europe
• cold benguela current moderates the climate of the Namibian desert

Question 15

human use of freshwater

Answer 15

• domestic purposes
• agriculture and irrigation
• industry
• hydroelectric power generation
• transportation

Question 16

sources of freshwater

Answer 16

• rivers
• streams
• resevoirs
• lakes

Question 17

underground aquifiers

Answer 17

• layers of porous rock sandwiched between two layers of impermeable rock
• filled continuously by infiltration of precipitation
• water flow is very slow

Question 18

issues with freshwater use

Answer 18

• climate change may be disrupting rainfall patterns
• underwater aquifiers are being exhausted
• irrigation often results in soil degradation
• industry releases pollutants into water bodies

Question 19

solutions to freshwater issues

Answer 19

• increase freshwater supplies
• reducing domestic use of freshwater
• selecting drought resistant crops reduces need for irrigation
• industries regulated to remove pollutants from wastewater

Question 20

marine ecosystems

Answer 20

• very biodiverse and have high stability and resilience
• 1/2 of all marine productivity is in continental regions above the continental shelf

Question 21

continental shelf

Answer 21

• upwellings bring nutrient rich water up to the continental shelf
• light reaches shallows so producers can photosynthesise

Question 22

fisheries

Answer 22

• 90% in oceans
• 10% in freshwater
• fisheries include shellfish and some vertebrae
• up to 500 million make livelihood off fisheries
• 3 billion gain 20% of their protein intake from fish

Question 23

aquaculture

Answer 23

• people in MEDC’s eating less meat and eating more fish and veg

Question 24

impacts of fish farms

Answer 24

• loss of habitats
• pollution
• spread of diseases
• escaped species include GM fish which outcompete others

Question 25

fish supply becomes exhausted through

Answer 25

• commercial fishing is informed by new GPS navigation
• fishing fleets have become larger
• indiscriminate fishing gear takes all organisms

Question 26

maximum sustainable yield

Answer 26

the highest amount that can be taken without depleting the stock

Question 27

optimum sustainable yield

Answer 27

requires less effort and maximises difference between total revenue and total costs

Question 28

biochemical oxygen demand

Answer 28

measure of the amount of dissolved oxygen required to break down the organic material in a given volume of water

Question 29

indicator species

Answer 29

show something about the environment by presence, absence or scarcity

Question 30

biotic index

Answer 30

measures pollution by assaying the impact on species within the community