Application of SPI, EDI and PNPI using MSWEP precipitation data over Marathwada, India

Drought is a natural hazard with severe socio-economic consequences. For agro-based country like India, this may further deteriorate the circumstances, thereby urging for precise quantification. This paper is about the application of meteorological drought indices namely Standardized Precipitation Index (SPI), Effective Drought Index (EDI) and Percent Normal Precipitation Index (PNPI) over Marathwada division, Maharashtra, India. The 3-hourly (0.25° × 0.25°) gridded rainfall data is collected from Multi-Source Weighted-Ensemble Precipitation (MSWEP) product for 1979-2014 and is converted to monthly temporal scale. All the three indices give similar results in meteorological drought characterization i.e., most parts of the Marathwada division are affected by frequent moderate or severe droughts while some parts have witnessed extreme drought conditions. However, EDI reveals a majority of the study area affected by extreme droughts, although with low frequency. This study will be helpful to policy makers for effective decision making regarding drought management.

1. Introduction

Drought is a ubiquitous natural disaster that ensues scarcity of water resources, decrease in groundwater storage and reduction in yield of plants. The sustained extreme droughts even intent critically social and monetary problems that have a huge impact on human life. Droughts affect wide range of sectors and thus, it is very difficult to define it in such a way that it will hold good for all the sectors. Hence, droughts are broadly classified into four categories. These are meteorological droughts, hydrological droughts, agricultural droughts and socio-economic droughts. Meteorological droughts are conventionally defined by magnitude of rainfall anomaly. When rainfall occurs lesser than 75 percent of mean value over a particular area [1], it is regarded as meteorological drought in United States whereas India Meteorological Department (IMD) prescribes its initiation for rainfall lesser than 10 percent to long term mean value [2]. The meteorological drought is typically distinguished by meteorological variables viz., precipitation and evapotranspiration [3] and considered as the root cause for all other types of droughts [4].