Geographical Analysis: River Systems and Arid Agriculture
Classified in Geography
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M12/3/GEOGR/HP2/ENG/TZ0/XX
2. (a) Río Grande de Santiago: Geographical Characteristics
[4 marks]
Describe the geographical characteristics of the Río Grande de Santiago downstream from La Presa.
Marking Scheme Guidance
- Award [1 mark] for meandering.
- Award [1 mark] for southwest direction.
- Award [2 marks] for other characteristics such as oxbow lakes or deltas.
- A maximum of [3 marks] will be awarded for a list of landforms with no overview or description.
- Full marks should not be awarded in the absence of map evidence (e.g., names or grid references).
1. (b) Human Activity and Water Flow Through Systems
[2+2+2 marks]
Explain three ways in which human activity can reduce the time taken for water to pass through the system.
Marking Scheme Guidance
Answers depend on the human activity or activities chosen, which may lead to:
- Land use changes (e.g., urbanization, deforestation, agriculture)
- River channel modifications
- Drainage systems
Note: Marks should not be allocated for "increased rainfall."
- Award [1 mark] for correct identification of a relevant human activity.
- Award [1 mark] for a valid explanation of how it reduces the time taken for water to pass through the system.
6. (c) Agriculture in Hot, Arid Areas: Opportunities & Challenges
[10 marks]
Examine the opportunities and challenges for agriculture in hot, arid areas.
Annual rainfall in these areas typically varies between 250 mm and 500 mm, offering some possibility for farming, especially where water conservation methods are employed.
Opportunities for Arid Agriculture
- Nomadism: The traditional method for coping with insufficient rainfall and pasture.
- Irrigation: Possible in areas close to rivers or oases.
- Drought-tolerant Species: Increased use of species adapted to arid conditions.
- Silt-laden River Water: Irrigating with this water can help restore soil in badly eroded areas.
- Land Enclosure: Used to reduce wind erosion.
Challenges for Arid Agriculture
Key challenges include water shortage and high temperatures. All arid and semi-arid areas experience a negative water balance. The water deficit can be compensated for by using irrigation water, including methods like central pivot irrigation and drip irrigation.
Soil Characteristics in Desert Areas
Desert soils are arid (dry) and often infertile due to:
- Low organic content, resulting from low biomass levels.
- Generally very thin composition with few minerals.
- Lack of clay (the amount of which typically increases with rainfall).
Salinization may occur in areas where annual precipitation is less than 250 mm. Saline soils adversely affect the growth of most crop plants by reducing the rate of water uptake by roots and germinating seeds. Desertification occurs when already fragile land in arid and semi-arid areas is overexploited.
Marking Scheme Guidance
Answers accessing Mark Bands E/F should include both the opportunities and challenges of farming in hot, arid areas, and refer to relevant examples or case studies.