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Causes of drought

Is Drought a ‘Natural Hazard?’. Causes of drought. ‘society is not a passive victim of drought’ Dr Anne Van Loon (2016) In your pairs/groups discuss the above statement – what do you think Dr Van Loon meant by it?. L/O: To compare the human and physical causes of drought.

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Causes of drought

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  1. Is Drought a ‘Natural Hazard?’ Causes of drought ‘society is not a passive victim of drought’ Dr Anne Van Loon (2016) In your pairs/groups discuss the above statement – what do you think Dr Van Loon meant by it? L/O: To compare the human and physical causes of drought

  2. The UN definition of drought ‘Drought is defined as an extended period – a season, year, or several years – of deficient rainfall relative to the statistical multi-year average for a region’

  3. Causes of drought

  4. Drought risk from Human Activities • Human responses to water shortages affect water levels in aquifers, rivers and reservoirs. • People have directly affected the development of drought by: • abstracting water from rivers and groundwater • altering the hydrology of rivers due to reservoirs and water transfer schemes. • People have also indirectly affected the development of drought by: • Changing land use (deforestation, overgrazing, urbanisation) • Altering hydrological processes

  5. Deforestation & Drought • The removal of vegetation has additional consequences: • Compaction • Reduced Organic matter (reduced moisture retention) • Removal of litter layer • This reduces infiltration (and therefore percolation) and increases surface runoff, which in turn reduces soil moisture storage and groundwater recharge.

  6. Case Study – The Sahel Region. Task – Create a fact file on the Sahel Region. Include Location and countries of the Sahel. Economic and political stability of those countries. Climate of the region. How is this climate being effected by human and climatic changes? Impacts on environmental, economic, social and political areas. Prediction of the future for the region. Name players involved, locals, NGOs, militia, employment sectors. Specific regions that can be studied. 1983-85 Famine in Ethiopia 2004-05 Darfur Region Great Green Wall Homework – Complete case study. Create similar CS for 2014-17 Californian drought.

  7. Homework Research these measures of drought: • Palmer Drought Severity Index (PDSI) • Crop Moisture Index (CMI) • Palmer Hydrological Drought Index (PHDI) Watch the videos from this link, in preparation for our lesson on Monday: https://www.metoffice.gov.uk/learning/atmosphere/global-circulation-patterns

  8. Create a table with Physical and Human causes of drought. Pick 2 from each column and create flow diagrams of how each cause can lead to desertification. Desertification – Land degradation in arid, semi-arid and dry sub-humid regions from various human and climatic factors.

  9. Exam Practice Study Figure 2. Explain how physical and human factors have contributed to the variation in water scarcity shown.(8)

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