Page 3 - MahaMADAT

Standardized Precipitation Index (SPI) and occurrence of Dry Spells are also

recommended. SPI is used as an indicator of deviation of rainfall from the normal and
can serve as a more robust statistical indicator under certain conditions as compared to

simple rainfall deviations. Dry spell, in contrast, is an indicator of anomalies in the
distribution of rainfall.

Following rainfall derivatives should be considered while calculating the mandatory

indices.
• Average / Normal Rainfall

• Actual Rainfall
• Rainfall Deviation

• Dry Spell

•
2. Impact Indicators:

Impact factors includes indices which are to be evaluated in conjunction with the
rainfall related data to assess the impact of rainfall deficiency. They are as follows:

1. Remote Sensing based Vegetation Indices

2. Crop Situation / Area Sown Indices

3. Soil Moisture based Indices
4. Hydrological Indices

5. Other Factors
6. Ground Truth Verification

Drought Declaration Schedule:

1. Drought declaration in the early season: Drought declaration during August month

may be carried out, if the seasonal conditions signify drought like situation. Deficit

rainfall in June and July with prolonged dry spells leading to significant reduction in crop
sown area can trigger the declaration of early drought.

2. Indicators for early season drought declaration: Rainfall deficiency based on
rainfall deviation and the dry spell as shown in Table 4.1 continue to be mandatory for

declaration. Among the impact indicators, reduction in crop sown area or failed sowing,

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MRSAC,Nagpur ©®