• Primary source of energy driving hydrological cycle is solar energy 1 mark
• Solar energy causes changes of state in water 1 mark
• Condensation of water releases (latent) heat energy causing air to rise/hurricanes 1 mark
• Solar energy causes the temperature differences that create winds/cause movement of water vapour in the atmosphere/advection 1 mark
• Kinetic/wind energy moves clouds (from ocean over land, usually) 1 mark
• Solar energy melts ice producing streams/lakes/rising ocean levels 1 mark
• Solar energy causes both transfers (e.g. advection) and transformations (e.g. evaporation) in hydrological cycle 1 mark
• Precipitation/run-off/streamflow occurs due to gravitational energy/difference in potential energy between the high and low positions 1 mark
• Transpiration is driven by opening of leaf stomata which is due to chemical energy (cellular respiration in mitochondria) 1 mark

4 marks max

Identifying Impacts up to 4 marks

• Melting will increase due to global warming/climate change/increased greenhouse gas emissions
• Freezing will decrease due to global warming/climate change/etc.
• Precipitation will be polluted due to acid formation/emissions of NOx & SOx/combustion of coal
• Precipitation could change/increase/decrease due to climate change/etc.
• Percolation/infiltration will decrease due to urbanization/soil compaction caused by overgrazing
• Run-off will increase due to urbanization/deforestation
• Warmer/polluted streams due to thermal/toxic pollution from industrial effluent
• Evaporation will increase due to global warming/climate change/etc.
• Evapotranspiration will increase due to global warming/climate change/etc.
• Evapotranspiration will be reduced due to deforestation
• Uptake by plants will be reduced due to deforestation/urbanization/long fallow periods
• Groundwater flow/aquifers will change dependent on climatic impacts/precipitation/rate of human extraction
• Cloud seeding increases precipitation (addressing problem of drought/fog around airports)

Quality of Diagram up to 3 marks

Award 1 mark for every 3 correctly labeled flows or storages. No marks for less than 3.

Maximum 2 marks if gradient is left as a fraction

Answers may include:

• 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
• Link a range of environmental value systems to specific management strategies
• Link environmental value systems to general approaches that improve or hinder widespread access to freshwater
• Consider geographical locations differing in freshwater availability/quality
• Consider societies of different economic development
• Provide examples of strategies and human management activities/approaches linked to specific value systems that impact water accessibility

Marks	Level descriptor
0	The response does not reach a standard described by the descriptors below and is not relevant to the question.
1–3	The response contains:• minimal evidence of knowledge and understanding of ESS issues or concepts • fragmented knowledge statements poorly linked to the context of the question • some appropriate use of ESS terminology • no examples where required, or examples with insufficient explanation/relevance • superficial analysis that amounts to no more than a list of facts/ideas • judgments/conclusions that are vague or not supported by evidence/argument.
4–6	The response contains: • some evidence of sound knowledge and understanding of ESS issues and concepts • knowledge statements effectively linked to the context of the question • largely appropriate use of ESS terminology • some use of relevant examples where required, but with limited explanation • clear analysis that shows a degree of balance • some clear judgments/conclusions, supported by limited evidence/arguments.
7–9	The response contains: • substantial evidence of sound knowledge and understanding of ESS issues and concepts • a wide breadth of knowledge statements effectively linked with each other, and to the context of the question • consistently appropriate and precise use of ESS terminology • effective use of pertinent, well-explained examples, where required, showing some originality • thorough, well-balanced, insightful analysis • explicit judgments/conclusions that are well-supported by evidence/arguments and that include some critical reflection.