Analysis of spatial and temporal rainfall characteristics of the North East region of India

This study explores the rainfall characteristics of the North East region of India using daily-recorded data between 1950 and 2013. The data analysis is mainly focused on the plain and plateau regions of the study area. Fractal analysis and continuous wavelet transform were utilized to explore the chaotic nature and multi-time scale features of the rainfall time series. Trends in the time series were detected by using the Mann–Kendall test and Sen’s slope estimator. Rainfall over the study regions is quite variable; from south to north and west to east, a high–low–high gradient in the spatial distribution in seasonal and annual rainfall was observed. The frequency of heavy (64.5 ≤ R ≤ 124.4 mm), very heavy (124.5 ≤ R ≤ 244.5 mm), and extremely heavy (R ˃ 244.5 mm) rainfalls and consecutive rainfall ˃ 30 days were observed higher in Meghalaya plateau, whereas the highest frequency of light rainfall was observed in the Tripura plain region. Significant rainfall trends (increasing/decreasing) on monthly and seasonal scales were detected in both study regions. Also, a progressive reduction in the frequency of different amounts of rainfall was detected in the Barak plain region and on the Brahmaputra plain region’s north-eastern side. The Hurst exponent extracted from the rainfall series revealed persistent behavior for most of the time series. Wavelet transform confirmed a periodicity of 4 years and 6 years in both plain and plateau regions with a 5% significance level. The result that comes out from this study shall be useful for irrigation and agricultural activity and may help the decision makers formulate comprehensive disaster management strategies.