How does a drought develop?
Drought occurs during prolonged high-pressure conditions within a particular region. This weather pattern causes a clear and cloud-less sky. Only little or no precipitation at all is falling.
The development of a drought depends on meteorological, pedological and vegetation conditions. Air temperature and wind conditions play a major meteorological role.
Soils which can store water for long periods of time are less prone to drought. The presence and the depth of a ground water body influence the occurrence of drought as well. A dense vegetation cover prevents the soil to dry up.
Droughts normally occur in arid and semi arid regions and in high mountain areas.
What damage can arise?
Sustained drought causes plants to display signs of dehydration: they stop growing, drop leaves and fruit, become discoloured and eventually wither. This can result in the failure of pasture and harvest yields. In self-sufficient regions, this means that shortages in food supplies can arise in addition to water shortages. In the worst case, famine can result. For example, over 1.5 million people died of starvation in India as a result of drought in the 1960s.
Effects on soil
Drought can cause soil erosion due to the effects of wind and flooding. Moreover, the drying out of soil causes cracks which reduce the volume of the soil. Soil defects can give rise to subsidence which, in turn, causes damage to buildings. In regions with frequent or extensive dry periods, the soil and vegetation can suffer severe damage from which they will not be able to recover. In such cases, the process of desertification starts.
Forest fires are another consequence of drought as dry and withered vegetation burns easily.