Spatial Drought Vulnerability Mapping for Regional Climate Resilience: A study over India’s Northeast including Bangladesh

Northeast India (NEI) plays a key role in national development and environmental security due to its ecological diversity, socioeconomic significance, and strategic importance. In addition to being highly susceptible to climatic extremes, it's crucial for the region to build resilience against such challenges. The NEI, a region traditionally known for its heavy rainfall during the monsoon months (June–September), has witnessed a significant shift in its climatic patterns. The monsoon season, once characterized by consistent rainfall, has now transformed into a flood-drought cycle occurring within the same year. Intense bursts of rainfall lead to widespread flooding, followed by prolonged dry spells that verge on drought conditions. While NEI's vulnerability to flooding has been extensively studied, its susceptibility to drought remains underexplored, despite its growing relevance in the region. Therefore, this study presents a spatial drought vulnerability mapping framework designed to enhance this resilience in NEI, including Bangladesh (NEIB)—a geographically and climatologically intertwined region encompassing diverse landscapes from mountains to coastal plains. The study assesses drought vulnerability for the historical period (1981–2014) and projects future vulnerability (2015–2100) under four Shared Socio-Economic Pathways (SSPs), considering different climatic and socio-economic factors. A total of 16 factors like precipitation, temperature, drainage density, land-cover, surface soil-moisture, population density, etc. are used in this integrated framework. These factors fall under four main categories – hydrology, meteorology, socioeconomics, and agriculture, which employ two Multi-Criteria Decision-Making methods: an Analytical Hierarchy Process and a Weighted Aggregate Sum Product Assessment. Out of all the factors, precipitation emerged as the most influential one, followed by potential evapotranspiration and temperature. The spatial drought vulnerability mapping categorizes the NEIB region into five levels of vulnerability: very low, low, moderate, high, and very high. Interestingly, none of the regions in the NEIB fall into the very low or very high vulnerability categories. Regions such as Tripura, Mizoram, West Bengal, and Bangladesh are categorized as highly vulnerable, while Sikkim, Arunachal Pradesh, and Meghalaya demonstrate greater resilience. Future projections indicate a significant shift in vulnerability patterns. Towards the end of the century (2071–2100), under the SSP585 scenario, the area classified as having moderate vulnerability is expected to decrease from ~85% in the historical period (1981–2014) to approximately ~70%, while the proportion of the region categorized as highly vulnerable is anticipated to rise from ~9% to ~25%. Both the methods demonstrated high accuracy and reliability, achieving Area Under the Curve values above 80% based on Receiver Operating Characteristic curves. A sensitivity analysis via the Stillwell Ranking Method indicated comparable performances by criteria suggesting the robustness of the framework that can be applied to other parts of the world. The findings from such a framework will be helpful to promote the need for actions to mitigate future increases in drought severity in susceptible areas, while the resilience of less-impacted regions might be utilized to derive adaptive measures. As challenges from climate continue to evolve, this study provides valuable information for policymakers and stakeholders seeking to increase regional resilience and achieve sustainable development.