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Any lack of water to satisfy the normal needs of agriculture, livestock, industry or human population may be termed as a drought. While generally associated with semi-arid or desert climates, droughts can also occur in areas that normally enjoy adequate rainfall and moisture levels. Scientifically speaking, there is no unique definition of drought. Drought carries a different meaning in keeping with the perspectives of a scientific discipline. Accordingly, three types of drought are usually defined:

Fig. 1. Photo showing drought affected area.

Types of Drought

Meteorological Drought:
Meteorological drought is defined by the deficiency of precipitation from expected or normal levels over an extended period of time. Meteorological drought usually precedes the other kinds of drought. According to the India Meteorological Department (IMD), meteorological drought is defined as occurring when the seasonal rainfall received over an area is less than 75% of its long-term average value. It is further classified as moderate drought if the rainfall deficit is 26-50% and severe drought when the deficit exceeds 50% of normal.

Hydrological Drought:
When there is a marked depletion of surface water resources such as very low stream flow, drying of lakes, reservoirs and rivers. It may also result in recession of spring flows and glaciers due to insufficient regeneration of seasonal snow cover.

Agricultural Drought:
Usually triggered by meteorological and hydrological droughts, agricultural drought arises when soil moisture and rainfall are inadequate during the crop growing season to support healthy crop growth to maturity, which situation causes extreme crop stress and wilting. The conditions of agricultural drought can arise, even in times of average precipitation, owing to soil conditions or agricultural techniques. In India, it is defined as a period of four consecutive weeks (of severe meteorological drought) with a rainfall deficiency of more than 50 per cent of the Long-Term Average (LTA) or with a weekly rainfall of 5 cm or less during the period from mid-May to mid-October (the kharif season) when 80 per cent of the country's total crop is planted, or six such consecutive weeks during the rest of the year.

Impacts of Drought

The impacts of drought are generally categorized as economic, environmental, and social:

Economic Losses:
Economic impacts refer to production losses in agriculture and related sectors, including forestry and fisheries, because of the reliance of these sectors on surface and subsurface water supplies. It causes a loss of income and purchasing power, particularly among the rural population of the country. All the industries which are dependent upon primary sector for their raw materials would suffer losses due to reduced supply or increased prices. Drought thus has a multiplier effect throughout the economy, which has a dampening impact on employment, flow of credit, and tax collections. If the drought is country-wide, macroeconomic indicators at the national level are adversely impacted.

Environmental Losses:
Lower water levels in reservoirs, lakes, and ponds as well as reduced flows from springs and streams would reduce the availability of feed and drinking water, and adversely affect fish and wildlife habitat. It may also cause loss of forest cover, migration of wildlife and their greater mortality due to increased contact with agricultural producers, as animals seek food from farms and producers are less tolerant of the intrusion. A prolonged drought may also bring increased stress for the endangered species and loss of biodiversity.

Reduced stream flow and loss of wetlands may bring changes in the levels of salinity. Increased groundwater depletion, land subsidence, and reduced recharge may damage aquifers and adversely affect the quality of water (e.g., salt concentration, increased water temperature, pH, dissolved oxygen, turbidity). The degradation of landscape quality, including increased soil erosion, may lead to a more permanent loss of biological productivity of the landscape.

Social Losses:
Droughts cause an enormous amount of social losses and deprivations, which arise from lack of income, conflicts among the water users, and out-migration of the population from the drought-affected areas. People seek to cope with drought in several ways which affect their sense of well-being: they withdraw their children from schools, postpone daughters' marriages, and sell their assets such as land or cattle. In addition to economic hardships, it causes a loss of social status and dignity, which people find it hard to accept. Inadequate food intake may lead to malnutrition, and in some extreme cases, cause starvation. Access and use of scarce water resources generate situation of conflict, which could be socially very disruptive. Inequities in the distribution of drought impacts and relief may exacerbate these social tensions further.

Strategies for drought management

The National Rainfed Area Authority under the Ministry of Agriculture in India has come up with a detailed management strategy plan for fighting drought in India. The plan is divided into two major sub groups: short term and middle/long term strategy planning. The gist o f the plan is enumerated below:

Short term strategies:

  1. Judicious use of surface and groundwater for drinking and irrigation.
  2. Ensuring availability of quality fodder to animals.
  3. Livestock management including establishment of fodder/feed depots.
  4. Selection of crops, cropping sequences and agronomic practices for drought affected areas.
  5. Promotion of subsidiary income and employment generating activities.
  6. Deployment of Information technologies for collection, storage and dissemination on real time basis.
  7. Adoption of modified irrigation practices.
  8. Rescheduling of irrigation roasters.
  9. Proper and optimum utilization of ground water for irrigation.
  10. Use of poor quality water for irrigation, with a strict adherence to standardized water quality guidelines.
  11. In-situ rain water conservation.
  12. Installation of tanks and farm ponds for ground water recharge.
  13. Application of contingent cropping.
  14. Application of suitable fertilizers and micro nutrients, intercropping, mixed cropping etc for optimized use of water for irrigation.
  15. Meticulous planning for Rabi and summer crops in case of failure of Kharif crops.

Middle/long term strategies:

  1. Judicious networking of rivers and other water bodies of high rainfall areas so that the transferred water can be used for ground water recharging or filling up dried lakes, water bodies etc.
  2. Ground water recharge in dry areas with introduced water, in-situ and ex-situ water harvesting.
  3. Less exploitation of ground water by resorting to low water demanding crops and adoption of precision micro-irrigation techniques.
  4. Formulation of strict guidelines for judicious use of water for domestic and industrial urpose in all drought prone areas.
  5. Recycling of used/waste waters after proper treatment and reclamation for agriculture, human and animal consumption.
  6. Enhancement of perennial vegetation in arid and semi arid regions.
  7. Development of fodder varieties of cultivated crops having tolerance for varying degrees of drought.
  8. Resorting to programme for improved livestocking, breeding and management.
  9. Upgradation and fine tuning of crops, cropping and farming systems.
  10. Exploiting under exploited and underutilized plant resources.
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