What are different types and effects of drought?

Drought is a deficiency in rainfall/precipitation over an extended period of time, usually a season or more. Drought is a caused at times due to direct or indirect human involvement. Basically, it is the shortage of water availability due to insufficient precipitation, over-usage of water from the sources, high rate of evaporation etc.Drought differs from other hazards as it has a slow onset, evolves over months to years, affects a large spatial extent, and cause little structural damage. Its onset, end and severity are often difficult to determine. The impact of droughts can span over economic, environmental and social sectors.

Drought differs from other hazards as it has a slow onset and evolves over months to years, affects a large spatial extent, and cause little structural damage. Its onset, end and severity are often difficult to determine. The impact of droughts can span over economic, environmental and social sectors.

Various Types of Droughts

The National Commission on Agriculture in India classified three types of drought viz. meteorological, agricultural and hydrological. Meteorological drought occurs when there is a significant decrease from normal precipitation over an area (i.e. more than 10 %). Hydrological drought is due to prolonged meteorological drought resulting in depletion of surface and sub-surface water resources. In the case of agricultural drought, the soil moisture and rainfall are inadequate to support healthy crop growth. Drought is also classified on the basis of the time of onset as early season, midseason and late season.

The Indian Meteorological Department (IMD) recognizes

• A drought week; when rainfall in a week is less than half of its normal amount,
• An agricultural drought; when four drought weeks occur consecutively during mid-June to September
• A seasonal drought; when seasonal rainfall is deficient by more than the standard deviations from the normal
• A drought year; when annual rainfall is deficient by 20 % of normal or more and
• Severe drought year; when annual rainfall is deficient by 25-40% of normal or more.

Effect of Drought

The effects of droughts can be classified into three main categories:

Environmental Effect

During drought, the combined effect of the shortage of water in canals, ponds, reservoirs as well as the increased sunlight causes a number of environmental conditions such as depletion of soil moisture, intense wild fires, vegetation stress and animal die-off.

Economic Effect

Drought negatively impacts the agricultural sector with a decline in crop production. The micro level impact of the droughts is felt at the level of village and household. The secondary impact of the drought is on the aspects of regional inequality, employment, trade deficits, debt and inflation. It can also result in food insecurity, water related health risks and loss of livelihood in various sectors of the economy including the agriculture.

Social Effect

Prolonged droughts lead to changes in the social structure of the affected region. People start migrating to places with better opportunities and thus over a period of time the people in the drought affected region spend less and are focused on surviving. Thus activities such as schooling, sports, healthcare takes a backseat.