Soil moisture-based winter–spring drought variability over West Karbi Anglong region, Assam, Northeast India using tree-rings of Pinus kesiya
Lamginsang Thomte, Abani Kumar Bhagabati, Santosh K. Shah
Abstract
Drought is increasingly becoming more frequent and intense over Northeast India (NEI). To understand the drought variability over the region, we developed a 151-year (1868–2018 CE) long tree-ring width chronology of Pinus kesiya from Assam, NEI. The correlation analyses of tree-ring width chronology with temperature, rainfall, normalized difference vegetation index (NDVI) and soil moisture were conducted. The tree-ring chronology showed significant positive correlation with previous October through current year March rainfall and negative correlation with mean temperature of March–June. Similarly, we observed positive correlation with NDVI and soil moisture for April–May and January–April, respectively. Soil-moisture being the most significant variable for winter-spring (January to April), was reconstructed since 1868. This reconstruction accounted for 23.3% of the variance of the observed soil moisture in the calibration period of 1982–2018 CE. The years of soil moisture deficit (drought) and wet soil moisture conditions were identified based on the percentile distribution. The major droughts and famines that occurred in India during the late 19th and early 20th century were observed in the reconstruction. This study adds additional input towards agricultural planning and management in NEI.