DROUGHT ANALYSIS USING SPI: A CASE STUDY OF MARATHWADA REGION

Abstract

Marathwada, one of the important regions in central India is infamous for its recurring drought situation. Marathwada is a part of Maharashtra state which plays a major role in country’s economy. It covers 8 districts of Maharashtra state in India with a geographical area of about 65,000 Km2. Climate in the region is dry and moderately extreme in nature. Annual rainfall ranges from 675 to 950 mm. Repeatedly affected by the scanty rainfall, this region is included in Drought Prone Areas (DPA) of India. Keeping this in view, the present study focuses on the time series analysis of historical monthly rainfall in Marathwada so as to analyse historical drought events and to predict the future drought events. To analyse the drought events, various drought indices are developed by various researchers. As the present study is based on rainfall series analysis of Marathwada, different rainfall based drought indices are evaluated namely Rainfall Departure (RD), Standardized Precipitation Index (SPI), Rainfall Decile based Drought Index (RDDI), Z-Score and China Z-Score (CZI) so as to identify characteristics of the drought events. The characteristics evaluated by these all drought indices are the also compared in this study. In order to be prepared for droughts, it highly important to get an alert about upcoming drought well in advance. Drought forecasting is the most important thing in this regard. In this study, an attempt is made to predict the drought situations by tracing the trends in rainfall in Marathwada. For this purpose, NCEP Reanalysis data is downscaled by Multiple Linear Regression (MLR) technique which is calibrated and validated against historical rainfall data. Future projection of the rainfall data is done by HadCM3_A2 (Hadley Centre Coupled Model, version 3) scenario. Future drought situations are then predicted and their characteristics are identified on the basis of SPI as SPI is considered as the most relevant drought index for regional climate. Evaluation of drought characteristics of the future drought events will help the water resources planners and managers to take corrective measures so as to manage the water resources on sustainable basis.