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Drought: causes, impacts and responses
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A desert is always dry. A drought is when somewhere has much less water than normal for a long time.
Arid areas and drought
Arid environments, such as hot deserts, are dry all the time.
A drought is a long period with much less precipitation than normal.
Meteorological drought: too little rain. Hydrological drought: rivers, lakes and groundwater fall low.
Human causes: irrigation for farming uses up water, dams reduce flow downstream, and deforestation reduces moisture returned to the air.
A drought is a long period with much less precipitation than normal.
Meteorological drought: too little rain. Hydrological drought: rivers, lakes and groundwater fall low.
Human causes: irrigation for farming uses up water, dams reduce flow downstream, and deforestation reduces moisture returned to the air.
Why some places are vulnerable
Areas near 30° north and south lie under sinking, dry air (high pressure) in the global circulation.
If the rain belt near the equator moves less far than usual, places on the edge of deserts, such as the Sahel, get little rain.
El Nino events change ocean temperatures in the Pacific and shift rainfall patterns worldwide, bringing drought to some regions.
If the rain belt near the equator moves less far than usual, places on the edge of deserts, such as the Sahel, get little rain.
El Nino events change ocean temperatures in the Pacific and shift rainfall patterns worldwide, bringing drought to some regions.
Two droughts compared
Developed: California, USA (2012 to 2016). Rivers and reservoirs fell, farmers left fields unplanted and pumped more groundwater, and wildfires increased. In 2015 the state ordered towns and cities to cut water use by 25%, and people were paid to replace lawns.
Developing: Ethiopia (2015 to 2016). Linked to a strong El Nino, the rains failed, crops and livestock died, and more than 10 million people needed food aid. The government's Productive Safety Net Programme, UN agencies and charities provided food, water and cash.
Developing: Ethiopia (2015 to 2016). Linked to a strong El Nino, the rains failed, crops and livestock died, and more than 10 million people needed food aid. The government's Productive Safety Net Programme, UN agencies and charities provided food, water and cash.
Explain why drought is more dangerous in Ethiopia than in California.
- Most Ethiopians depend directly on rain-fed farming for food and income.
- There is less money for reservoirs, piped water and imported food.
- California can buy food and store water, so drought harms the economy more than lives.
Answer: Dependence on rain-fed farming and less money to cope make people far more vulnerable.
Arid areas are always dry; drought is unusually low rainfall over a long time. Causes: meteorological, hydrological and human (irrigation, dams, deforestation). Places near 30° and on desert edges are vulnerable, especially in El Nino years. California cut water use; Ethiopia needed food aid.
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