droughts Flashcards
def. arid
an environment that receives less than 250mm of rainfall annually ( extremely dry)
def. drought
a prolonged period of abnormally low rainfall, leading to a shortage of water
name the two natural causes of a drought
Meteorological
Hydrological
meteorological drought?
when the amount of precipitation received in a specific area is less than the average.
hydrological drought?
when reduced precipitation impacts on water supply
restriction in water
name 3 human causes of a drought
deforestation
agriculture
dam building
how can deforestation effect droughts
trees reduce evaporation, store water
leads ground vulnerable to erosion
how can agriculture effect droughts
using large amounts of water to irrigate crops removes water from lakes, rivers and groundwater
irrigation def.
supply water to land or crops to help growth
how does dams effect droughts
large dams can be built across a river (to produce electricity and store water in a reservoir). (This can reduce river water flowing downstream) and cause drought below the dam.