Drought assessment and trend analysis using SPI and SPEI during southwest monsoon season over Bundelkhand region of Uttar Pradesh, India

Abstract

Drought is a climatic anomaly that can occur in all regions with vastly different climate. A persistent lack of precipitation over an extended period scaling usually a season or more results water stress that significantly impacts economic, agricultural, environmental and social aspects. For an effective monitoring of drought condition, drought indices play major role which are region specific and have limitation of applicability in different climatic condition. Hence, the present study aims to analyse the climatology and drought by two drought indices viz. Standard Precipitation Index (SPI) and standardized precipitation evapotranspiration index (SPEI)) for Bundelkhand region, the most drought prone area of Central India by using 48 years (1969-2016) rainfall and temperature data. The trend analysis was performed at a significance level of 5% by using non parametric Mann-Kendall (MK) test and Sen’s slope estimator with the help of XLSTAT 2021 software. The SPI and SPEI were calculated with the SPEI R package in R-Studio software. The study revealed that i) the southwest monsoon (June to September) contributed 88.8-91.8% of total annual rainfall with coefficient of variation (CV) of 29.9-39.5%. ii) A non- significant decreasing trend in rainfall was noticed for almost all the districts during July, August and September. However, a significant (0.05 level) and decreasing trend was observed in July (4.03 mm rainfall/year) and August rainfall (4.03 mm rainfall/year) for Hamirpur. iii) The frequency of moderate drought events increased followed by severe and extreme drought events. The decreasing trends of SPI-3 and SPEI-3 were also observed which indicates more dry spells during southwest monsoon season. iv) A good correlation (r= value of 0.88 to 0.91) was observed between SPI-3 and SPEI-3 during southwest monsoon season which indicates the importance of theses indices for assessment of drought in the study region.