Droughts: Concepts, Assessment and Management in Rainfed Regions

Abstract

Drought agriculture occupies about 68% of India’s cultivated area and supports nearly 40% and 60% of the human and livestock populations, respectively. It produces 44% of food requirements, thus, has and will continue to play a critical role in India’s food security. However, aberrant behaviour of monsoon rainfall results in frequent droughts that impact resource poor farmers more severely than in the irrigated ecologies. Eroded and degraded soils with low water holding capacity and multiple nutrient deficiencies, declining groundwater table, etc. contribute to low crop yields that lead to further land degradation. It has been estimated that even if the country’s full irrigation potential is realized, agricultural production in about 75 million ha will continue to be solely dependent on rainfall. About 15 million ha of dryland lies in the arid region which receives <500mm rainfall; another 15 million ha is in 500-750 mm rainfall Zone, 42 million has is in 750-1150 mm rainfall zone, with the remaining 25 million ha receiving >1150mm rainfall per annum. Droughts occur once in 3 to 5 years either due to a deficit in seasonal rainfall during the main cropping season or from inadequate soil moisture availability during prolonged dry spells between successive rainfall events. Drought is a normal, recurrent climatic feature that occurs in virtually every climatic zone around the world, causing billions of dollars in loss annually for the farming community. Bryant (1991) ranked natural hazard events based on various characteristics, such as severity, duration, spatial extent, loss of life, economic loss, social effect and long-term impact. He found that drought ranks first among all natural hazards. Unlike flood and hurricanes that develop quickly and last for a short time, drought is a creeping phenomenon that accumulates over a period of time across a vast area and the effect lingers for years even after the end of the drought. In spite of the economic and the social impact caused by drought, it is the least understood of all natural hazards due to the complex nature and varying effects of droughts on different economic and social sectors (Wilhite, 2000).