Dynamics and impacts of monsoon-induced geological hazards: A 2022 flood study along the Swat River in Pakistan

Abstract

This study examines the impacts of the unprecedented 2022 monsoon season in Pakistan's Swat River basin, where rainfall exceeded historical averages by 7 %-8 %. This extreme weather led to catastrophic debris flows and floods, worsening challenges for low-income communities. The resulting financial instability affected millions, causing significant damage to homes, crops, and transportation. The study employs a multidisciplinary approach, combining field investigations, remote sensing data interpretation, and numerical simulations to identify the factors contributing to debris flow incidents. Analysis of land cover changes reveals a decrease in grasslands and an increase in barren land, indicating the adverse effects of deforestation on the region. Topography and gully morphology are crucial in initiating debris flows, with steep gradients and shallow-slope failures predominant. Numerical simulations show that debris flows reached high velocities of 18 m s-1 and depths of 40 m within 45 min. Two debris flows resulted in the formation of dams along the Swat River, intensifying subsequent floods. The study emphasizes the interplay of extreme rainfall and deforestation during the rainy season, rendering the region susceptible to debris flows and hindering restoration efforts. Recommendations include climate change mitigation, reforestation initiatives, and discouraging construction activities in flood-prone and debris-flow-prone regions. The study advocates for enhanced early warning systems and rigorous land use planning to protect the environment and local communities, highlighting the imperative of proactive measures in the face of escalating climate challenges. Additionally, the study investigates the spatial distribution of various events and their consequences, including potential hydrometeorological triggers, and how such events initiate processes that change mountain landscapes. It also assesses the extent to which the 2022 monsoon can be classified as abnormal. The combination of empirical evidence and practical insights presented in this study highlights research gaps and proposes routes toward a deeper understanding of monsoon-triggered geological hazards and their consequences.