What causes drought?
Lack of rainfall (or precipitation)
Droughts can occur when there is a lack of ‘expected’ precipitation (rain and snow). Note that we say ‘expected’ because the lack of rain alone does not mean a drought. Some regions can go for months without any rain, and that would be normal for them. Farmers plant in anticipation of rains and so when the rains do not come, and irrigation infrastructure is absent, agricultural drought occur.
Surface water flow
Some regions are also well distributed with surface water (streams and rivers) that have their sources from far away mountains and watersheds. These surface waters may dry out if the flow from their sources upstream is affected. Hydro-electric dams and irrigation systems are some of the economic activities that can reduce the amount of water flowing to other areas downstream.
Forests (trees) play a key role in the water cycle, as they help reduce evaporation, store water and also contribute to atmospheric moisture in the form of transpiration. This means cutting down trees (deforestation) in the name of economics, will expose surface water to more evaporation. It will also reduce the ability of the ground to hold water and make it easier for desertification to occur. It can set off drying conditions, especially for smaller water bodies. Cutting down trees is known to reduce a forest’s watershed potential.
Even though some people do not accept that the average temperature of the earth has risen, it is on record that human actions have contributed to more greenhouse gasses in the atmosphere. As a result, there are warmer temperatures, often resulting in more dryness and bush fires. These conditions also tend to speed up drought conditions.