Causes of drought

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  • Causes of Drought
    • Types of Drought
      • meteorological - presents a degree of dryness compared to what is considered normal precipitation for the area, climate and season
      • agricultural - when there is insufficient water for crops - loss of crops
      • hydrological - drainage basins suffers shortfalls such as reduced streamflow or an increase of river flow into the reservoirs
      • socio-economic - demand for water for reasons e.g crop irrigation or when HEP exceeds water availability
    • ENSO - El Nino
      • winds weaken and reverse direction
      • warm water moves to the South American coastline - low air pressure causes large increases in rainfall - more flood
      • Australia - cooler ocean temperatures and high air pressure - little rainfall and risk of drought
    • ENSO - La Nina
      • reverse of El Nino risks
    • short term precipitation deficit
      • change of weather front
    • Human Causes - Brazil
      • 2014-15 - industries, farmers and domestic users using groundwater till rivers run low
        • poor and rural communities are suffering because they only had access to groundwater
      • Gov introduced charge for drilling wells - $35,000 to $100,000
        • residents drilled illegally because they could not afford the charge - not monitored
          • official records of wells drilled in 2014 only represent 1/3 of total
      • water from illegal wells are shallow - may have more agricultural pollutants and bacteria
        • increase in poor sanitation, water borne diseases

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