The term drought can be defined by several ways:
• Condition where crops that are unable to mature because to a lack of water provided by rain.
• The situation where amount of water required by agricultural plants for transpiration and evaporation in a specified region exceeds the amount of accessible moisture in the soil.
• A condition in which there has been no precipitation for more than 15 days in a rainy season. Dry spells are defined as periods of time when there are no wet days.
“Condition in which the amount of water needed for transpiration and direct evaporation exceeds the amount available in soil.”
According to general concept, droughts can be classified into 3 categories:
a) permanent drought
b) seasonal drought
c) intermittent drought
Based on the nature of impact and spatial extent
– Meteorological Drought: Meteorological drought occurs when annual rainfall falls significantly below a threshold of 75% of the climatologically expected normal rainfall across a large area.
Every state receives a particular amount of regular rainfall in each region. This serves as the foundation for determining the region’s or area’s cropping pattern.
Meteorological drought is commonly described by the degree of dryness (in comparison to a “normal” or “average” quantity) and the length of the dry period.
Because the atmospheric conditions that cause a lack of precipitation vary greatly from place to region, meteorological drought must be defined on a region-by region basis.
– Hydrological drought: This is a circumstance in which hydrological resources such as streams, rivers, reservoirs, lakes, and wells dry up due to significant surface water depletion. The groundwater table is also depleted, affecting industry, power generation, and other significant revenue-generating sectors. When a meteorological drought lasts for a long time, a hydrological drought develops.
– Agricultural Drought: This is a scenario that occurs as a result of insufficient rainfall, followed by a soil moisture shortage. As a result, the soil moisture is insufficient to fulfil the growing demands of the crops.
Because the soil moisture accessible to a crop is insufficient, it inhibits growth and, as a result, yield. Early-season drought, mid-season drought, and late-season drought are the three types of droughts.