Water Cycle eq2 Flashcards
define drought
extended period of deficient rainfall relative to the statistical average for a region measured iver a very long period of time
What are the causes of drought?
- dams
- deforestation
- ENSO cycles
- changes in precipitation patterns
- irrigation (65%)
4 types of drought
- agricultural drought
- socioeconomic drought
- hydrological drought
- meteorlogical drought
what makes an area more vulnerable?
- if they are directly dependant on the land
- poverty
- lack of preparedness
What are the economic impacts of drought?
- reduced water levles
- decreased agricultural productivity
What are the environmental impacts of drought?
- fire hazard
- soil erosion
What are the social impacts of drought?
food shortages
4 key causes of meterorlogical drought
- natural variations in the atmosphere
- El Nino events
- Changing land use
- Climate change creating regional and local effects
3 atmospheric circulation cells
- polar
- ferrel
- hadley
intertropical covergence zone
Sometimes the subtropical high pressure zones, associated with the descending parts of the convection cell (Hadley cell) block the high humidity, rain bearing air masses associated with the ITC2, so that the pattern is modified
mid-latitudes blocking anticyclones
meterological drought
- low air pressure affected by jett streams
- high pressure areas from tropics move northwards
- stable weather conditions with little precipitation
- block weather systems for up to 2 weeks
- normal precipitation greatly reduced
normal conditions in the pacific
- warm water
- Australia
- low pressure
- risk of flooding
- cold water
- south america
- high pressure
- risk of drought
El Nino conditions in the pacific
- warm water
- south america
- low pressure
- risk of flooding
- cold water
- australia
- high pressure
- risk of drought
El Nina conditions in the pacific
- warm water
- Australia
- low pressure
- risk of flooding
- cold water
- south america
- high pressure
- risk of drought
(enhanced normal conditions)
direct human causes of drought
taking water direclt from a store (abstractation)
indirect human causes of drought
altering hydrological processes (deforestation)