Changes in the probability of temporally compound wet and dry events in a warmer world: case study in the Upper Jhelum Basin-South Asia

Abstract

Temporal compound events (TCEs), such as the consecutive occurrence of two complementary extremes of the hydrological spectrum (floods and droughts), exhibit a volatile hydrological cycle that exacerbate the challenges associated with water resources management. This study makes use of bias-corrected climate models output from three modeling experiments (CMIP6, CORDEX, and CORDEX-CORE), to examine moderate to extreme wet and dry events and their temporal compounding over the Upper Jhelum Basin (UJB), under low, medium, and high emission scenarios for two future periods (2040?2059 and 2080?2099). Standardized Precipitation Evapotranspiration Index (SPEI) is used to quantify the meteorological wet and dry events that are the main driver of the hydrologic floods and droughts. The two types of TCEs considered in the current study are wet-to-dry (W-to-D) events and dry-to-wet (D-to-W) events in the adjacent month. Results indicate that (1) under warming conditions, wet and dry events are expected to become more frequent and severe whereas duration of the events exhibits distinct change signals depending on the specific location. (2) The basin is more prone to D-to-W TCEs dominated in the southwest of the region, which was not found to be hotspot historically neither for dry nor for wet extreme events. (3) CORDEX and CORDEX-CORE ensembles show varying climate change signals with no specific spatial pattern whereas the CMIP6 ensemble shows stronger change signals and divides the region into two distinct parts, i.e., northeast and southwest.