4 Flashcards
How many percent of all water on Earth is fresh water? List fresh water storages in decreasing order of size. Which are renewable and which are not?
- glaciers and ice caps - non renewable
- aquifers (ground water)
- lakes
- swamps
- rivers - renewable
List storages and flows of hydrological cycle. What is it driven by?
Energy from solar radiation drives the hydrological cycle.
STORAGES: oceans, glaciers, aquifers, lakes, rivers, soil, atmosphere
FLOWS: advection, precipitation, evaporation, condensation, freezing, evapotranspiration, currents, infiltration & percolation, surface run-off
What impact do humans have on the water cycle?
Increase of population and improvement of quality of life results in:
- withdrawals - domestic use, irrigation
- discharges - pollution
- channeling rivers, dams, building roads
- deforestation
Explain how ocean circulation system works (ocean currents).
They occur due to differences in water density from different salinity and temperature. Cold water coming from the poles is more salty as the salt is left behind in the process of frezzing. It is denser than warm water so it sinks to the bottom while being replaced by less salty and dense warm water.
That is how the conveyor belt is driven, which distributes heat around the world and affects climate.
What is water scarcity?
It is inaccessibility of water due to bad planing in infrastructure (economical scarcity) or demand exceeding the resources (physical scarcity).
List issues related to water use.
- climate change -> disrupts rainfall paterns, low water levels on lands, high levels of oceans
- exhaustion of aquifers
- pollution
- irrigation - water evaporates before being absorbed, dissolved minerals from fertilizers make it salty
How to solve water scarcity?
- reservoirs, rainwater harvesting, desalination plants, redistribution, recharging aquifers
- reduce domestic use, reuse grey water
- reduce amount of pesticides, swithc to organic ones
- minimalize evaporation
- ban pouring out hot water
Give and elaborate on two examples of water wars.
WEST BANK:
- Palestine and Israel disagree on who owns the water
- water is under military control
- Palestine needs to pay for most of the water even though it is extracted from their territory
MEKONG DAMS (China vs Myanmar, Vietnam, …):
- people along the river depend on it and the dams built in the upper part of teh river disrupt its flow
- water levels are falling down -> sedimentation increases
- pollution
What is aquaculture?
Farming of aquatic organisms involving interventions to enhance production.
What are the impacts of aquaculture?
- loss of habitats
- chemical pollution (antibiotics, feed)
- escaped species may outcompete native species
- spread of diseases
- death of predators that prey on farmed species
Discuss with reference to a case study controversial harvesting of a named species.
Seal is a major food source of Arctic peoples. Hunting seal is part of a healthy, traditional way of life, as they provide not only food with all needed minerals but also medicine. However they are becoming endangered as a result of hunting.
Describe the ‘tragedy of commons’.
If a resource is seen as belonging to all, we tend to over-exploit it because “if we don’t, someone else will”.
What is maximum sustainable yield (MSY)? Why does it usually lead to population decline?
Highest amount that can be taken without permanently depleting the stock.
- its a model
- it doesn’t take into account sex & age
- diseas may strike a population
What strategies can be used to avoid unsustainable fishing?
- control the number and size of fishing vessels
- protect critical areas
- require science based catch limits
Discuss a case study that demonstrates the impact of aquaculture.
ATLANTIC SALMON:
Wild salmon is over-exploited. Most of the one we can buy is raised on farms in the Pacific. Some conconsider salmon farms to pose a threat to wild salmon, as they escape from farms and may outcompete native species, which are already stuggling. On farms they live in nets, densely packed, as to generate the most profit, which works in favour of diseas spread. Social impacts mainly include abusive labor practice and exploitation of poorer countries.
