Trends and Variability of Rainfall in Tripura State of India in 1986–2019 and Key Drivers

Changes in rainfall patterns can have a profound impact on water availability, and therefore, examining the variability of rainfall is critical in addressing water resources and regional climate change. Tripura state of northeast India is known to have received a high amount of rainfall in the past few decades, but currently the region suffers from water shortage as soon as the rainy season retreats. Here, we use the surface, satellite and reanalysis data of Tripura in 1986–2019 to examine the seasonal and annual trends in rainfall. The satellite and reanalysis data agree very well with the surface rainfall measurements for Tripura and reproduce the seasonal and inter-annual variability. We find a decreasing trend in the seasonal and annual averaged rainfall at most stations for the period 1986–2019. The monsoon rainfall is declining at a rate of 0.025–0.216 mm/year, with the highest rate of −0.216 mm/year at the Sabroom station during the period. The correlation analysis of rainfall with land use and land cover (LULC) suggests the impact of LULC on rainfall; indicating the anthropogenic influence in rainfall changes there. Our analysis also shows a substantial increase in the Arabian Sea and Bay of Bengal sea surface temperature (SST) after 2000, and the changes in SST with respect to the El Niño, La Niña and Indian Ocean Dipole events contribute significantly to the rainfall variability in the region; suggesting plausible causes of recent changes in regional climate in the northeast.