13-Statistical method of estimate drought occurrence.

Abstract

Rayalaseema region of Andhra Pradesh is chronically drought prone. The climate is generally dry with very low annual rainfall. R, laseama region comprises four districts viz., Ananthapur, ittoor, Cuddapah and Kurnool. Chittoor district is located - southern part of Andhra Pradesh. Rainfall data collected from nearly 16 raingauge stations covering the entire 15000 sq.km area of Chit'toor district is statistically analysed to determine the frequency of occurrence of the drought pattern and the results are presented in this paper.

The annual rainfall values are tabulated and it is shown that the data conform to Log Pearson Type-III distribution. Based on this, the mean, standard deviation and the skew coefficients are computed and the amount of rainfall having different return periods are obtained. Using the definition proposed by the India Meteorological Department for moderate drought and severe drought, the probability of occurrence of a few typical combinations of droughts of different intensities are obtained.

It is believed that the method of approach proposed would be of value in predicting the occurrence of drought in general and the results obtained in this study would of use in planning the drought management in Chittoor district of Andhra Pradesh.