EQ2 Flashcards
What are the three types of drought?
Meteorological, agricultural, hydrological and socio-economic time
What is meteorological drought-
When the long term percipitaion is low. It is area specific.
What affects meterorological drought?
Happens after low rainfall, high temp and higher evotranspiration. High temperatures, high winds, strong sunshine which are all causes of higher evaporation
What is agricultural drought?
Happens after a long meteorological drought. Not enough water for the crops.
What is hydrological drought?
Difference between surface and sub surface water. After a long time you see less water in rivers
What is socio-econmic drought?
Not enough water for the humans to use can be after a agricultural drought or due to overconsumption of water.
Example of meteorological drought?
2013 in California there was 34% lower water supply
Example of hydrological drought?
In California there was less groundwater and higher soil dryness plus 108 million trees died.
Example of socio-economic drought
38 million residents went through a 31 month drought. Power outages
Example of agricultural drought
Lower groundwater and agricultural was dependent on it
Human causes of drought in Australia
42% taken out the river. 90% of the vegetation removed since 1800s. 3,5 million people rely on this
How long was the big dry( Millennium drought)
12 years and 12% less rain
Physical causes of drought
Australia lies on a high pressure belt. (Ferrel cell). 94 of rainfall evapourates. El nino caused more dry conditions. Global warming
How much did suddam hussein drain the iraqi marshes?
Now only 10% of their orginal size
What did it cause?
Lower infiltration. Lower percipitaion. Evapouration increases. Species die. Flooding and soil erosion
Why are the marshes not resilent?
Soil erosion removes nutrients so hard for vegetation to grow. Cannot begin succession.
What do wetlands do?
Flood control. Groundwater store. Water purification. Food. Nutrient recycling
What is Praire land?
Land that used to absorb water but now has been paved over
Case study for Humans increasing flood risk?
Houston
What did Houston do?
Built over Prairie wetlands which used to stop flooding as they absorb the water. Reduced deep absorption
What else did Houston do?
Making a third highway which further reduces the amount of wetlands
Whose at risk?
700,000 people and more then 5 billion in damages
What else do humans do?
Straighten channels which increases speed of water. Impeding Chanel use by building bridges.
