Relative influence of ENSO, IOD, and AMO over spatiotemporal variability of hydroclimatic extremes in Narmada basin, India

The Narmada basin is one of the major river basins of Central India. The basin frequently experiences droughts and floods due to its geography and uneven topography. Therefore, it is important to understand the spatiotemporal variability of hydroclimatic extremes over the basin. Large-scale climate oscillations (LSCOs) have been observed significantly affecting the patterns of hydroclimatic extremes at the basin and continental scale. In this study, we have analysed the relative influence of LSCOs (EL Nino-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Atlantic multidecadal oscillation (AMO)) over hydroclimatic extremes of the Narmada basin. Precipitation, temperature, and streamflow extremes were analysed in stationary and nonstationary frameworks of generalized extreme value distribution. The precipitation extremes, PRCPTOT and R95p were observed significantly influenced by ENSO, IOD, and AMO individually whereas extreme Rx5day was relatively more influenced by ENSO and AMO individually and collectively. Temperature extremes, TXx was significantly more influenced by ENSO alone (26.47% of the region), while TNx was observed to be substantially more influenced by ENSO and AMO. The upper Narmada basin was found vulnerable to flooding and whereas the basin was projected to experience more frequent and intense heatwave-associated disasters in long term.