资源环境科技发展态势分析平台

Current study presents an integrated approach to assess the hydroclimatic teleconnections of large-scale coupled oceanic-atmospheric circulations on basin-scale extreme rainfall and streamflow indices for climatologically sensitive Tapi basin, India. The trend analysis of rainfall extremes revealed spatial heterogeneity across the basin. The coastal and mountainous regions of Lower and Upper Tapi basins respectively experienced wet conditions, while the plains of Middle and Upper Tapi (Puma sub-catchment) basins exhibited drier conditions during the analysis. The decreasing trend in high streamflow indices (except for Burhanpur sub-catchment) and significant increasing trend in low flow days (except for Lower Tapi basin) are observed, indicating the dominance of drier and moisture deficient conditions across Tapi basin. The hydroclimatic teleconnections of largescale oceanic-atmospheric circulations of tropical Pacific and equatorial Indian Ocean regions, i.e., El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) respectively, with hydrometeorological extremes in Tapi basin for the concurrent period are investigated. As Indian summer monsoon rainfall (ISMR) and Tapi basin monsoon rainfall (TBMR) shows explained variance of around 42%, the influences of ENSO and IOD circulations on TBMR may be asymmetric with ISMR. The anomalous warming of the Indian Ocean, i.e., positive IOD (pIOD), and co-occurrence of pIOD and weak El Nino conditions, are associated with higher flood risk across the basin vis-a-vis other ENSO and IOD conditions. On other hand, the effects of ENSO and IOD are not apparent on low flow days, as the anthropogenic changes in the basin including streamflow regulations have considerably influenced the low flow regimes. The time interlocking between ENSO-IOD conditions and streamflow extremes in Tapi basin is further envisaged by performing a lead-lag correlation analysis.