A detailed assessment of meteorological drought characteristics using simplified rainfall index over Narmada River Basin, India

Drought is amongst the most precarious phenomena that cause serious repercussions, especially over the agriculture-dominated regions. A detailed assessment of droughts is necessary to develop robust frameworks for combating its ill effects. This study presents an analysis of meteorological drought characteristics (frequency, severity and persistence) using precipitation data of twenty-four districts for 1954–2013 over the Narmada River Basin, which is located in the core of the Indian Monsoon region and has great agricultural importance. Further, the entire duration is divided into two epochs, i.e. 1954–83 and 1984–2013, for comparative analysis. A simplified rainfall index (RI_S) is proposed, which is based on the concept of percentage deviation from normal monsoon rainfall along with the uniform transition from moderate to severe and severe to extreme droughts. The basin is found to be prone to droughts and the drought frequency varied from once in three to 8 years over different districts. The droughts are more frequent and severe in the western portions of the basin as compared to the eastern portions. The majority of the districts have undergone droughts persisting for 3 years at least once. The epoch-wise analysis reveals a significantly higher frequency, severity and persistence of droughts in the recent epoch. The results of trend analysis using the Modified Mann–Kendall test indicate an increasing trend of droughts over twenty-one districts and significantly increasing over eleven districts. The information reported in this study will be helpful for proper planning and management of water resources over the basin and hence, reduce the pernicious effects of droughts.