drought

• drought

  • occurs when areas drier than normal, high temps and low levels of precip, high levels of evapotranspiration
• meterological and hydrological causes

  • short term droughts- precipitation deficits, high pressure air systems
  • el nino cycle can cause drought
• el nino

  • enso cycle is a natural change in patterns of ocean temperatures in the pacific ocean
  • el nino event- pressure increases in the western pacific and decreases in the east, causing trade winds to weaken in strength or change direction
  • west- sinking of air can cause drought as less precip falls
  • occur every 3-4 years
• human activity causes drought

  • overabstraction in australia
  • and deforestation can cause drought eg Amazonia
• how drought affects ecosystems

  • wetlands act as water purifiers which trap pollutants however in drought conditions they dry up causing vegetation die back
  • algae becomes more concentrated as water levels drop- eutrophication