Drought analysis using Standardized Precipitation Index (SPI) in Kerala

The Standardized Precipitation Index (SPI) is a relatively new drought index based on the probability of precipitation for a time scale. The Standardized Precipitation Index (SPI) values were calculated for five agro climatic zones of Kerala viz. Northern Zone, High Range Zone, Central Zone, Problem Area Zone and Southern Zone, during southwest monsoon season by using 30 years monthly rainfall data by using the programme SPI_SL_6. The 4-month time scale for the 9th month (September), which is the combined SPI for the months of September, August, July and June, was used to study the SPI for southwest monsoon. SPI values were negative (dry condition) for 19 years, positive (wet condition) for 15 years and near normal for 1 year at Northern Zone and there were 7 drought events (SPI <= -1.00). SPI values were negative (dry condition) for 15 years and positive (wet condition) for 20 years at High Range Zone and there were 9 drought events (SPI <= -1.00) and 1 of them was meteorological drought event. At Problem Area Zone SPI values were negative (dry condition) for 16 years and positive (wet condition) for 19 years and there were 5 drought events (SPI <= -1.00) and 3 of them were meteorological drought events. SPI values were negative (dry condition) for 19 years, positive (wet condition) for 16 years at Central Zone (Vellanikkara station) and there were 5 drought events (SPI <= -1.00) and one of them was meteorological drought event. SPI values were negative (dry condition) for 16 years, positive (wet condition) for 19 years at Central Zone (Pattambi station); 4 drought events (SPI <= -1.00) and all of them were meteorological drought events except 1. At the Southern Zone SPI values were negative (dry condition) for 16 years, positive (wet condition) for 19 years; 7 drought events (SPI <= -1.00) and three of them were meteorological drought events. The more number of dry conditions were experienced at northern zone and central zone during southwest monsoon/ kharif season. Proper crop planning has to be done at those areas and crops like millets, pulses, vegetables etc. with short growing period, can be recommended with proper moisture conservation practices.