Spatiotemporal Assessment of Drought Dynamics and Periodicity in Southern Districts of West Bengal, India

Abstract

Drought is a recurring issue in the southern districts of West Bengal, impacting agriculture, water resources, and livelihoods. Climate variability exacerbates these challenges, necessitating a comprehensive assessment of drought severity and trends over time. The main aim of this study is to assess the spatiotemporal dynamics of drought from 2003 to 2021 by evaluating drought severity, analyzing trends in drought severity categories, and identifying periodic cycles that influence drought conditions. Advanced drought indices such as the Standardized Precipitation-Evapotranspiration Index (SPEI), Temperature Condition Index (TCI), Vegetation Condition Index (VCI), and Vegetation Health Index (VHI) were employed. The study utilized remote sensing data and innovative trend analysis (ITA) to assess the severity, trends, and periodicity of drought. Wavelet power spectrum (WPS) analysis was also applied to examine drought periodicity across multiple time scales. Quantitative results show that severe and extreme drought conditions have significantly intensified over the past two decades. Extreme drought affected up to 7,258 km² in 2009, while severe drought reached a peak of 12,217 km² in 2021. Moderate drought remained the most prevalent category, affecting over 17,146 km² in 2009. Areas classified under no drought conditions steadily declined, from 16,327 km² in 2017 to 10,581 km² in 2021. ITA results indicate an increasing trend in extreme and severe drought areas, with more regions transitioning from mild to severe categories. Periodicity analysis revealed significant multi-year cycles (8-16 years) for extreme and severe droughts, aligning with known climate anomalies. These findings emphasize the escalating severity and frequency of drought in the region, underscoring the urgent need for adaptive management strategies, continuous monitoring, and timely interventions to sustain agricultural productivity and ecosystem health amidst intensifying climate change impacts.