Evaluation of the Drought Trend Alongside of Change Point: A Study of the Purulia District in West Bengal, India

Abstract

Since the drought is a significant issue in India, therefore, the scientists should pay close attention in order to manage it. Purulia District experienced the drought on numerous occasions in the past ten years, but the accurate and definite conclusions have not arrived yet. Hence, the Standardized Precipitation Index (SPI) for the 34 years (1979–2014) was utilised in this research together with the change point to evaluate the annual and seasonal drought in the Purulia District. Theil Sen's slope and the Mann-Kendal (MK) test were both employed to determine the trend and its’ magnitude. A trend-free pre-whitening technique was used to remove the influence of lag-1 correlation data from the series. The 1988-89 was marked as the best probable single change (shift) point in the time series of SPI. By calculating the percentage deviation from the SPI's mean trend, the magnitude of the change was calculated. The percentage change of Sen's slope and MK test was high (+ve) at the eastern parts of Purulia, whereas it was observed as the smallest at the southern parts of the region. Thus, it could be concluded that the drought had begun to spread to the study region's eastern sections after the change point. As Purulia is dependent on agricultural crop production, this research would significantly contribute to agricultural planning following the local level management of crop water and rain-water harvesting. Therefore, this research is extremely important for the drought risk management on a regional scale.