Chapter 4

Question 1

Water budget

Answer 1

A quantitative estimate of the amounts of water in storages and flows of the water cycle

Question 2

What drives the water cycle

Answer 2

Energy from solar radiation and the force of gravity

Question 3

Water: renewable and non-renewable

Answer 3

Depending on where it is stored, can easily slide from being renewable to non-renewable if poorly managed

Renewable: atmospheres, rivers
Middle ground: groundwater aquifers
Non-renewable: oceans and icecaps

Question 4

Aquifer

Answer 4

A layer of porous rock, sand or gravel underground that holds water. In aquifers, it takes longer than a human lifetime to replenish the water extracted

Question 5

Water cycle - transfers

Answer 5

Stays in the same state: advection (wind-blown movement), flooding, surface run-off, infiltration and percolation (when water runs into and through soil or rocks), stream flow and current

Question 6

Water cycle - transformations

Answer 6

Evapotranspiration (liquid to water vapour), condensation (water vapour to liquid), freezing (into solid snow and ice)

Question 7

Water cycle - storages

Answer 7

Oceans, soil, groundwater (aquifers), lakes, rivers and streams, atmosphere, glaciers and ice caps

Question 8

Human impact on water cycle

Answer 8

Withdrawals (domestic use, irrigation in agriculture/industry)

Discharges (adding pollutants to water, chemicals, fertilisers, sewage)

Changing speed at which water can flow/where it flows (building roads, channelling rivers, canalizing, dams, barrages and dykes, reservoirs)

Diverting rivers or sections of rivers (to avoid flood damage, to improve storage)

Question 9

Canalizing

Answer 9

Straightening large sections of rivers in concrete channels to facilitate more rapid flow through sensitive areas

Question 10

Flash floods

Answer 10

Occur when rainfall or snowmelt cannot infiltrate the soil and runs off on the surface

Due to land being hard-baked in hot, dry areas, but due to the CITY-based surface (urbanization!!!)

Question 11

Ocean currents

Answer 11

Movements of water both vertically and horizontally. They move in specific directions and are found on the surface and in deep water

Question 12

Ocean currents importance

Answer 12

Global distribution of energy

Without them, we could not understand the global atmospheric energy changes

Question 13

Surface currents

Answer 13

Upper 400m of ocean, are moved by the wind

Earth’s rotation deflects them and increases their circular movement

Question 14

Deep water currents (thermohaline currents)

Answer 14

Make up 90% of ocean currents and cause the oceanic conveyor belt

Question 15

Deep water currents key ideas

Answer 15

Due to differences in water density caused by salt and temperature

Warm water can hold less salt than cold water so is less dense and rises - cold water holds more, sinks

Question 16

Upwellings

Answer 16

When warm water rises, cold has to come up from depth to replace it

Question 17

Downdwellings

Answer 17

When cold water rises, it has to be replaced by warm water

Question 18

Cold ocean currents

Answer 18

Runs from the poles to the equator (e.g. Humboldt Current and Benguela Current)

Question 19

Warm ocean currents

Answer 19

Flow from the equator to the poles (e.g. Gulf Stream and Angola Current)

Question 20

Water and its effect on temperature

Answer 20

Water has a higher specific heat capacity than land
Water masses heat up and cool down more slowly than landmasses
Land CLOSE to seas and oceans has a mild climate with moderate winters and cool summers

Question 21

How ocean currents affect local climate

Answer 21

Gulf Stream moderates the climate of Northwestern Europe, which otherwise would have a sub-arctic climate

(Cold) Benguela Current moderates the climate of the Namibian desert

Humboldt Current impacts the climate in Peru

Question 22

El Niño Southern Oscillation (ENSO)

Answer 22

A phenomenon in the Pacific Ocean - pressure differences across the ocean is reversed (called the Southern Oscillation)

These pressure differences alter both the directions of the wind and the warm surface current

Question 23

El Niño Southern Oscillation (ENSO) effects

Answer 23

Local effects - collapse of anchovy fish stocks, massive death of sea birds and storms and flooding in the coastal plain of Peru

Question 24

Humans use fresh water for…

Answer 24

Domestic purposes (drinking, washing, cleaning), agriculture (irrigation, for animals to drink), industry (manufacturing, mining), hydroelectric power generation, transportation (ships), marking the boundaries between nation states (rivers and lakes)

Question 25

Water scarcity

Answer 25

A measure of how much water there is and how we use it

Question 26

Major rivers

Answer 26

Danube River - runs through 19 countries and is shared by 81 million people Who owns the water? another Tragedy of the Commons -> many disputes over who owns it, especially since it becomes increasingly needed and scarce

Question 27

Sources of freshwater

Answer 27

Surface freshwater (rivers, streams, reservoirs and lakes) and underground aquifers

Question 28

Aquifer

Answer 28

A layer of porous rock (holds water) sandwiched between two layers of impermeable rock (does not let water through)

Question 29

Aquifers key ideas

Answer 29

water flow in aquifers is extremely slow -> aquifers often used unsustainably many are also 'fossil aquifers', meaning that the recharge source is no longer exposed at the surface and they are never refilled -> these can NEVER be used sustainably

Question 30

Problems related to freshwater use

Answer 30

Climate change disrupts rainfall patterns, causing further inequality of supplies Low water levels in rivers and streams (e.g. Colorado River, now is a tiny stream) Slow water flow in the lower courses of rivers results in sedimentation, which makes the already shallow river even shallower Underground aquifers are being exhausted, aquifer cannot be used anymore -> strongly affects agriculture

Question 31

Problems related to freshwater use (part 2)

Answer 31

Pumping rates from aquifers are too fast -> causes exhaustion making the well unusable Freshwater becomes contaminated and unusable Fertilisers and pesticides used in agriculture often pollute water streams and rivers Industries release pollutants into surface water bodies Industries and electricity plants release warm water into rivers

Question 32

Irrigation

Answer 32

Often results in soil degradation, especially in dry areas

Question 33

Salinisation

Answer 33

Water used in irrigation evaporates before it is absorbed by the crops. Dissolved minerals remain in the top layer of soil, making it too saline (salty) for further agriculture

Question 34

Effects of warm water in rivers

Answer 34

Holds less dissolved oxygen than cold water, so aquatic organisms that take oxygen from water (fish) are negatively affected Changes the species composition in the water

Question 35

Solutions to problems related to freshwater use

Answer 35

increase freshwater supplies by reservoirs, redistribution, desalinisation plants, rainwater harvesting systems (large and small scale), artificially recharging aquifers Reduce domestic use of freshwater by using more water-efficient showers, dishwashers, and toilets Wash cars in car washes with a closed water system Grey-water recycling - water from showers, baths etc that can be reused for garden irrigation, flushing, etc Selecting drought resistant crops can reduce the need for irrigation

Question 36

Solutions to problems related to freshwater use (part 2)

Answer 36

Reduce the amount of pesticide and fertiliser used, prevent over-spray directly into a stream Replace chemical fertilisers with organic ones (release of nutrients is slower and more likely to be absorbed) Use highly selective pesticides instead of generic pesticide Industries can remove pollutants from their wastewater with water treatment plants Regulate maximum temperatures of released cooling water (don't release warm water)

Question 37

Grey water

Answer 37

Very lightly used water that can be reused (to irrigate gardens, clean cars, flush WCs, etc)

Question 38

case study: Israel's water shortage

Answer 38

greatest water drought in the past decade, caused by population growth and an improvement in quality of life (greater desire to water lawns and gardens) will launch a conservation campaign, targeting mostly household use - has already reduced by more than 50% the drinking water supplied to farmers, increasing their need for recycled water has two desalinisation plants that supply about 1.3 of water needed

Question 39

case study: China's Three Gorges dam

Answer 39

this hydroelectric dam on the Yangtze river was one of the largest engineering projects in the world (estimated cost US$30 billion) provides 9% of all China's output, savings in CO2 emissions are huge, also stops river from flooding criticisms: environmental degradation, refugees, destroy archaeological sites, threaten wild species, silt up, pollution from building the dam risk of energy security - if it is destroyed, all of this power generation is lost ( too dependant?)

Question 40

Marine ecosystems

Answer 40

Oceans, mangroves, estuaries, lagoons, coral reefs, deep ocean floor - are usually very biodiverse and so have high stability and resilience

Question 41

Continental shelf

Answer 41

The extension of continents under the seas and oceans

Question 42

Importance of continental shelf

Answer 42

Has 50% of oceanic productivity but 15% of its area Upwellings bring nutrient-rich water up to the continental shelf Light reaches the shallow seas (producers can photosynthesise) Countries can claim it as theirs to harvest and exploit

Question 43

UN Convention on the Laws of the Sea (UNCLOS)

Answer 43

1982 - designated continental shelves as belonging to the country from which they extend

Question 44

Phytoplankton

Answer 44

Single-celled organisms that can photosynthesise and are the most important producer in the oceans, producing 99% of primary productivity

Question 45

Zooplankton

Answer 45

Single-celled animals that eat phytoplankton and their waste

Question 46

Marine organisms can be classified as...

Answer 46

Benthic - living on or in the sea bed | Pelagic - living surrounded by water from above the sea bed to the surface

Question 47

Fishery

Answer 47

When fish are harvested in some way. It includes capture of wild fish (also called capture fishing) and aquaculture or fish farming

Question 48

Aquaculture

Answer 48

The farming of aquatic organisms in both coastal and inland areas involving interventions in the rearing process to enhance production

Question 49

Why is fish farming increasing?

Answer 49

Diets changing - more fish instead of meat with saturated fat

Question 50

Ways in which fish farming is sustainable

Answer 50

Fishmeal uses more trimmings and scraps which would have been wasted in the past Livestock and poultry processing wasted is also substituted for fishmeal US Department of Agriculture has proven that 8 species of carnivorous fish can get enough nutrients from alternative sources without eating other fish

Question 51

Fish farms impacts

Answer 51

Loss of habitats Pollution (with feed, antifouling agents, antibiotics and other medicines added to the fish pens) Spread of diseases Escaped species including genetically modified organisms which may survive to interbreed with wild fish Escaped species may also outcompete native species and cause the population to crash

Question 52

Fish stocks are shrinking because

Answer 52

Industrialised nations subsidise their modern fleets by an estimates US$50 billion a year Demand outstrips supply

Question 53

Sustainable yield (SY)

Answer 53

The increase in natural capital (e.g. natural income that can be exploited each year without depleting the original stock or its potential for replenishment) 

Question 54

Sustainable yield of an aquifer

Answer 54

The amount that can be taken each year without permanently decreasing the amount of water stored

Question 55

Maximum sustainable yield

Answer 55

Highest amount that can be taken without permanently depleting the stock

Question 56

Carrying capacity for each species depends on

Answer 56

Its reproductive strategy, its longevity, the indigenous resources of the habitat/ecosystem

Question 57

Sustainable yield formula

Answer 57

(Total biomass at time t + 1 / energy) - (total biomass at time t / energy) or Annual growth and recruitment - annual death and emigration

Question 58

Why harvesting the MSY leads to population decline and loss of resource base

Answer 58

Population dynamics of the target species are normally predicted (modelled) rather than the species numbers being measured (counted) Often impossible to be precise about the size of a population Estimates are made on previous experience Model does not allow for monitoring of the dynamic nature of the harvest in terms of age and sex ratio Disease may strike the population

Question 59

If you extract/harvest at the MSY, you will...

Answer 59

Deplete a population in poor recruitment years

Question 60

Optimal sustainable yield (OSY)

Answer 60

Requires less effort than MSY and maximises the difference between total revenue and total cost Has a much greater safety margin than MSY, still may have an impact on population size if there are other environmental pressures within a system