Spatio-temporal evolution of wet–dry event features and their transition across the Upper Jhelum Basin (UJB) in South Asia

摘要

The increasing rate of occurrence of extreme events (droughts and floods)and their rapid transition magnify the associated socio-economic impactswith respect to those caused by the individual event. Understanding ofspatio-temporal evolution of wet–dry events collectively, theircharacteristics, and the transition (wet to dry and dry to wet) is thereforesignificant to identify and locate most vulnerable hotspots, providing thebasis for the adaptation and mitigation measures. The Upper Jhelum Basin(UJB) in South Asia was selected as a case study, where the relevance ofwet–dry events and their transition has not been assessed yet, despiteclear evidence of climate change in the region. The standardizedprecipitation evapotranspiration index (SPEI) at the monthly timescale wasapplied to detect and characterize wet and dry events for the period1981–2014. The results of temporal variations in SPEI showed a strong changein basin climatic features associated with El Ni?o–Southern Oscillation(ENSO) at the end of 1997, with the prevalence of wet and dry events beforeand after 1997 respectively. The results of spatial analysis show a highersusceptibility of the monsoon-dominated region towards wet events, with moreintense events occurring in the eastern part, whereas a higher severity andduration are featured in the southwestern part of the basin. In contrast, thewesterlies-dominated region was found to be the hotspot of dry events withhigher duration, severity, and intensity. Moreover, the surrounding regionof the Himalaya divide line and the monsoon-dominated part of the basin werefound to be the hotspots of rapid wet–dry transition events.