There are four types of drought based on agricultural
- Permanent drought
There is a constant excess of
evapotranspiration over precipitation.
Vegetation is limited to desert dwelling plants
causing agriculture to be impossible.
- Seasonal drought
This type of drought only occurs at the
margins of great deserts where there are arid
conditions for most of the year. Agriculture here
is only successful during the wet seasons.
- Contingent drought
Contingent droughts are experienced in
areas that normally have enough moisture. Problems
arise in these regions from poor framing and irrigation.
- Invisible drought
There are no physical changes to the landscape
from this drought even though evaporation and
transpiration exceed precipitation. Vegetation
lacks the moisture required for optimum growth. The
potential agricultural yield of the land is reduces,
but this problem is easily dealt with by the used of