Warning and early forecasting of droughts

Drought is a normal recurrent feature of climate and occurs in all climatic regions and is usually characterized in terms of its spatial extension, intensity and duration. Conditions of drought appear when the rainfall is deficient in relation to the statistical multi-year average for a region, over an extended period of a season or year or even more. It is slow on-set and hence difficult to determine the beginning and end. It requires continuous monitoring of climate and water supply indicators. Impacts are difficult to quantify, are cumulative and effects magnify when events continue from one season to another. Impacts of droughts may be direct or indirect.
Direct impacts include:
-Reduced agricultural production
-Increased fire hazard
-Depleted water levels
-Damage to wildlife and fish habitats
-Higher livestock & wildlife mortality
Indirect impacts include:
-Social impacts
-Economic impacts and
-Environmental impacts

Drought monitoring can be carried out using:

• Monitoring and early warning system
• Key drought indicators
• Developing a composite index and
• Drought monitoring checklist

Early warning system:

• Receive forecasts, early warning and advisories from scientific institutions
• Monitor key indices amd
• Develop composite index of various drought indicators

1. IMD is the designated agency for providing drought early warning and forecasting. IMD monitors agricultural drought every two weeks on a real-time basis during main crop seasons (Kharif and Rabi) of India. An Aridity Anomaly Index based on the lines of Thronthwaite's concept is used to monitor the incidence, spread, intensification and recession of drought. The Drought Research Unit at IMD Pune, provides crop yield forecasts using pre-harvest crop yield forecasting models and issues forecasts for Kharif and Rabi crops based on agro-meteorological models.
2. The National Centre for Medium Range Weather Forecasting (NCMRWF) in collaboration with IMD, Indian Council for Agricultural Research (ICAR), State Agricultural Universities (SAU) provides agro-climatic zones to the farming community based on location specific medium range weather forecasts. The Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad and the All India Coordinated Research Projects on Agrimeteorology and Dryland Agriculture (AICRPAM & AICRPDA) each have 25 centers across SAUs across the country and take part in drought studies pertaining to assessment, mitigation, risk transfer and development of Decision Support Software (DSS) for drought prone states. 
3. The ministry of earth sciences in collaboration with ICAR has set-up 89 centers for short and medium range monitoring and forecasting of weather.
4. The National Agricultural Drought Assessment and Monitoring System (NADAMS) developed by department of space for the department of agriculture primarily monitors the vegetation through National Oceanic and Atmospheric Agency's (NOAA) Advanced Very High Resolution Radiometer (AVHRR) data. Drought assessment is based on a comparative evaluation of satellite observed green vegetation cover of a district in any time period with that of any similar period in previous years. This comparative evaluation helps in fixing current season in the scale of historical agricultural situations.