Monthly and Seasonal Dryness and Wetness Assessments Based on Rainy Days and Its Magnitude

Drought is a natural phenomenon which occurs often unpredictably. It affects larger communities mainly who depends more on rainwater for their crop cultivation. It is a natural that it occurs at different magnitude over a year. The number of rainy days in each month usually have large variations among them as it depends on the seasons. Indian meteorological department (IMD) has provided a categorization of rainfall based on amount of daily rainfall amount. The number of rainy days in each categorization will have an impact in addressing varying intensity of dryness and wetness. As the number of rainy days in each categorization is important over the year apart from annual rainfall amount, the index based on this could help to understand the climate of the region in better way. In the present study, a new index for drought or wet year assessment is presented based on IMD’s rainfall categorization. The proposed index is applied to Thanjavur city rainfall data and drought categorization is carried out as per the new index. The results of the study indicate that the proposed index is found to be effective in assessing drought conditions by simple calculation.