Analysis of Meteorological Drought Using Standardized Precipitation Index (SPI) in the Dry Areas of Southern Karnataka, India

Abstract

Karnataka is the second largest state after Rajasthan in India in terms of area under rainfed agriculture and experiences the impact of rainfall aberrations. The state consists of five dry zones that contribute a substantial part of state’s agricultural production. Of the five dry zones, three fall in southern Karnataka, which are the major contributors to production of finger millet, pigeon pea, ground nut, etc. Because rainfall is the major source of moisture, the spatio-temporal distribution is to determining the fate of crop production in the domain. Long-term (1992-2021) datasets on rainfall were used to assess droughts in the taluks of three dry zones of Karnataka (EDZ, SDZ & CDZ) using the Standardized Precipitation Index (SPI) at a 12-month time scale and the outcomes were classified based on the SPI. Further, frequency, duration, severity and intensity analysis were carried out to characterize the drought in each taluk. The results revealed that a smaller number of extreme annual droughts were observed than near normal annual droughts (17-22 years). The frequency of dry years (SPI< -0.99) varied between 2-7 years, with maximum dry years observable at Shrinivasapura, Bangalore South and Gouribidanur taluk in Eastern dry zone, Kadur and Molakalmur taluks in the Central dry zone and Krishna Raja Pete, Turuvekere and Kunigal taluk in Southern dry zone of Karnataka. Major extreme drought events were observed during 2012, 2015 and 2016 because of the severe negative deviation of rainfall from normal during those years, and were more severe in the Maddur (-3.52), Harihara (-2.57) and Shidlaghatta (-3.394) taluk in the Southern, Central and Eastern dry zone, respectively. Furthermore, among the drought classes, the frequency of moderate drought events was higher than that of severe and extreme drought events, indicating the planning of crop management practices to overcome the impact of extreme drought event which are less frequent but devastating.