Outline how energy drives the hydrological cycle.

Explain, with the use of a system diagram, how human activities affect flows in the global water cycle.

To what extent do the approaches and strategies of different environmental value systems improve access to fresh water?

primary source of energy driving hydrological cycle is solar energy;
solar energy causes changes of state in water eg evaporation/sublimation/melting/transpiration;
condensation of water releases (latent) heat energy causing air to rise/hurricanes;
solar energy causes the temperature differences that create winds/cause movement of water vapour in the atmosphere/advection;
kinetic/wind energy moves clouds (from ocean over land, usually);
solar energy melts ice producing streams/lakes/rising ocean levels;
solar energy causes both transfers (eg advection) and transformations (eg evaporation) in hydrological cycle;
precipitation/run-off/streamflow occurs due to gravitational energy/difference in potential energy between the high and low positions;
transpiration is driven by opening of leaf stomata which is due to chemical energy (cellular respiration in mitochondria).

Award up to [4 max] for identifying following impacts either on the diagram or in words:

melting (1) will increase due to global warming/climate change/increased greenhouse gas emissions;
freezing (2) will decrease due to global warming/climate change/etc;
precipitation (4,6,8) will be polluted due to acid formation/emissions of NO_x & SO_x/ combustion of coal;
precipitation (4,6,8) could change/increase/decrease due to climate change/etc;
percolation/infiltration (8) will decrease due to urbanisation / soil compaction caused by eg overgrazing;
run-off (5) will increase due to urbanization/deforestation;
warmer/polluted streams (5) due to thermal/toxic pollution from industrial effluent;
evaporation (3,7,9) will increase due to global warming/climate change/etc;
evapotranspiration (10) will increase due to global warming/climate change/etc;
evapotranspiration (10) will be reduced due to deforestation;
uptake by plants (11) will be reduced due to deforestation / urbanization / long fallow periods;
groundwater flow/aquifers (12) will change dependent on climatic impacts/precipitation / rate of human extraction;
cloud seeding increases precipitation (4,6,8) (addressing problem of drought/fog around airports).

Award up to a further [3 max] for quality of diagram, giving 1 mark for every 3 correctly labelled flows or storages. No marks for less than 3.

Refer to paper 2 markbands, available under “your tests”  tab > supplemental materials

The following guide for using the markbands suggests certain features that may be offered in responses. The five headings coincide with the criteria given in each of the markbands (although ‘ESS terminology’ has been conflated with ‘Understanding concepts’). This guide simply provides some possible inclusions and should not be seen as requisite or comprehensive. It outlines the kind of elements to look for when deciding on the appropriate markband and the specific mark within that band.

Answers may include:

• understanding concepts and terminology of availability & distribution of water; water security; climate change; water pollution; sustainable management of freshwater resources; reservoirs; desalination; artificial recharge; water conservation; environmental value systems; increasing demand for water; water scarcity; etc:
• breadth in addressing and linking a range of environmental value systems to specific management strategies AND general approaches that improve or hinder widespread access to freshwater in a range of geographical locations differing in freshwater availability/quality and societies of different economic development; etc;
• examples could include a range of strategies and human management activities/approaches linked to specific value systems that impact water accessibility;
• balanced analysis of the extent to which different management strategies / political decisions / legislation and agreements linked to a range of environmental value systems influence, both positively and negatively, the global accessibility of freshwater;
• a conclusion that is consistent with, and supported by, analysis and examples given eg ‘I believe that all environmental value systems have something to offer when considering access to fresh water, however an anthropocentric value system may be most successful as it will implement strategies that include the best of both extremes of technological scale and personal life styles’.