Drought and Groundwater Hydrologic Response

The definition of drought varies across countries and also within different areas of a country. Half of India, at any point of time, generally suffers from some kind of drought conditions. A meteorological drought3 is defined as 'a sustained, regionally extensive, deficiency in precipitation condition' (Ramachandran, 2000). The impacts of meteorological drought on water resources, agriculture as well as social and economic activities give rise to what have been called hydrological4 and, most important for our purposes, agricultural5 droughts.

Agricultural drought occurs widely in India. About 68% of net sown area in India is highly vulnerable to agricultural drought. Most of this area is located in the 60% of the country that is arid and semiarid (Tenth Five Year Plan, 20022007). When drought occurs, there is a loss of biomass along with essential soil-building microorganisms due to the denuded soils being subjected to prolonged periods of dryness. As pressure on resources grows, there is often no time for the land to recover before it is put to use again.

Effects of prolonged agricultural drought, particularly in western India, are manifest in the form of drastic declines in groundwater levels. Out of the 7928 assessment units, 673 units fall under the overexploited category and 425 units under the 'dark' category. Gujarat falls in the highly overexploited category.6

As also highlighted by Shah (Chapter 2, this volume), data from the Minor Irrigation Census (Government of India, 1996) have shown that continuous decline of groundwater levels has resulted in a large number of wells and bore wells going dry in many parts of India. In western India, where depletion is the highest, more than 50% of the wells and bore wells are out of commission.

The most recent major drought spell in India was from 1999 to 2002/03, with conditions in 2000 being most severe. In 2000, as can be seen from Table 12.1, almost 55,000 villages or 12% of India's total were affected. The state of our case study region, Gujarat, too suffered from drought during the same period, again with 2000 being the most severe. In fact, the situation was so severe that not only water for agriculture but also drinking water for cattle and human consumption was in extremely short supply.

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