Drought assessment using standardised precipitation evaporation index and its association with southern oscillation index in the Northwestern Bangladesh

The trend of drought in the northwestern region of Bangladesh was analysed in this study. To analyse the trend of the multiscalar drought index standardised precipitation evaporation index (SPEI), Mann-Kendall's test and Sen's slope estimator have been used. Assessment of variability of SPEI was conducted by means of the continuous wavelet power spectrum. Significant variability of 6 month scale SPEI was found at 16 to 32 months and 32 to 64 month period from almost 1987 to 2008. To grasp the influence of the southern oscillation index (SOI) on a 6 month scale SPEI, statistical tool wavelet coherence (WTC) has been used. Significant wavelet coherency was observed between SOI and 6 month SPEI at higher periodicity and short time span.…