Comparative Study of Meteorological Drought Indices in Amravati District

Water is increasingly becoming scarce resource in many parts of the world. Precipitation deficiency due to natural climatic variability in space and time is the primary cause of drought. Drought is a complex phenomenon that is difficult to accurately describe. The most common tool used to monitor drought is a drought index. Drought characterization is one of the important aspects in crop planning and resource development in rainfed farming areas. In this study, monthly rainfall at nine tehasils in Amravati district of Maharashtra was analyzed to estimate and compare decile drought index, effective drought index (EDI) and standardized precipitation index (SPI) for identifying drought years using 22 years rainfall data (1991–2012). Decile drought index identified maximum number of years in moderate drought category and widespread drought during 11 years. Effective drought index identified maximum number of years in normal condition and only one year 1995 as widespread drought year. SPI identified maximum number of years in mild wet condition and widespread drought was observed in four years in Amravati district. The three indices were compared using seven assessment criterion adopted by Ntale and Gan (2003). The SPI was found to be superior over that of decile index and EDI because it describes all the major droughts occurred in Amravati district, it has higher positive values of Spearman rank correlation coefficient between year wise crop yield data and climatic severity, it shows more consistency with historical drought events, it is easily adapted to the local climate, it can be computed at almost any time scale, it has no theoretical upper or lower bounds and it fulfills the criteria of data requirement and availability for its assessment. SPI can be considered as the most suitable index for drought assessment in Amravati district.