Computation of the spatio-temporal extent of rainfall and long-term meteorological drought assessment using standardized precipitation index over Kolar and Chikkaballapura districts, Karnataka during 1951-2019

Abstract

Drought is an insidious meteorological and hydrological natural phenomenon causing many adverse impacts on the environment, agriculture, and socio-economic condition, especially over a semi-arid region like Kolar and Chikkaballapura district in the state of Karnataka. When the precipitation level is inadequate to meet the demands of human activities, it leads to drought extension over a season or longer period. The present article is investigating the application of the standard precipitation index (SPI) to detect drought incidents and is widely used to understand rainfall variability. Therefore, this study attempts to analyze drought at pre-monsoon, southwest monsoon, northeast monsoon, and annual time period using SPI for Kolar and Chikkaballapur districts of Karnataka state. The outcome of this analysis demonstrates that drought occurrences are frequent in particular years and seasons with negative values of SPI along with dry, wet, and normal events. To apply any management plan with the increasing nuisance, deep knowledge is essential about meteorological, agricultural, and hydrological drought. The rainfall data for the period 1951–2019 at the eleven grid points were acquired from the India Meteorological Department with (0.25⁰ × 0.25⁰) high spatial resolution. The result revealed that a moderate dry event was observed in the pre-monsoon period at Kolar in 1993 with −0.67. Extreme drought condition was recorded during the southwest monsoon season in 1980 at Kolar with −2.22 and for the northeast monsoon, −1.67 was observed at Malur station in 1988. The seasonal crops of the southwest monsoon (June–September) are heavily dependent on this rainfall and it contributes to 58% of the annual precipitation. If there is a drop in the rainfall received during the southwest monsoon, the effect on the growing stage of agricultural crops leads to reduced crop yield.