Compound Hydroclimatic Extremes Under Anthropogenic Influence: Transition Patterns and Population Exposure Risks

Abstract Compound hydroclimatic extremes (CoHEx), characterized by transitions between prolonged dry and wet spells, intensify droughts and floods, thereby increasing risks to hydrological systems and regional water security. While previous studies have examined their frequency and spatial extent, the mechanisms governing their transitions under climatic and anthropogenic influences and how these generate compound behaviors remain poorly understood. This study investigates the seasonality and coupled drivers of CoHEx and their transitions in a large, climate‐sensitive, reservoir‐regulated basin in India using an integrated framework that combines circular statistical methods, causal diagnostics, and reservoir modeling. The approach reveals lagged and directional linkages between meteorological and hydrological anomalies, highlighting how reservoir regulation can either amplify or buffer hydroclimatic extremes. Atmospheric signals offer early indications of inflow variability, while streamflow governs short‐term reservoir outflow decisions, demonstrating the coupled nature of climate, hydrology, and human interventions in shaping compound extremes. A strong basin‐wide coupling ( r = 0.74) between meteorological and hydrological responses highlights the combined influence of catchment buffering and operational regulation. Land‐use transitions between 1991 and 2020, from forests and croplands to urban areas and shrublands, have contributed to increased streamflow. Although less frequent, CoHEx events exposed significantly larger populations than isolated wet or dry extremes, with impacts rising 1.5‐fold between 2000 and 2020. By capturing interactions among climate variability, land‐use change, and water infrastructure, this study offers a transferable approach to diagnose compound extremes and highlights the need for integrated early warning systems, adaptive reservoir operations, and sustainable land–water management to enhance resilience.