Extreme precipitation events in the Indian Himalayas frequently lead to devastating floods and landslides, posing significant risks to communities and infrastructure. This talk explores the multiscale atmospheric mechanisms driving these events, highlighting the interaction between large-scale circulation patterns and regional dynamical processes. Emphasis will be placed on tropical–extratropical interactions, moisture transport dynamics, and recent high-resolution modelling efforts aimed at improving prediction and early-warning systems in complex mountainous terrain.

Matti-Esko Järvenpää is the head of GCC operations in Finland. He is also the Director of structures division at WSP Global Inc. He has over 20 years of experience in engineering and management positions.

Urban flooding has become one of the most critical challenges in modern city management due to rapid urbanization, increased impervious surfaces, and inadequate drainage infrastructure. It not only disrupts mobility and damages property but also poses risks to health, safety, and economic productivity.It is driven by high-intensity, short-duration rainfall events, reduced time of concentration (ToC), and the proliferation of impervious surfaces that limit natural infiltration. Effective assessment requires integrated hydrologic and hydraulic (H&H) modeling that represents rainfall-runoff generation, surface flow routing, drainage network hydraulics, floodplain interactions, and the influence of urban topography and land use. These models simulate how stormwater moves through urban catchments, identify bottlenecks in the drainage system, and help in designing resilient infrastructure. Commonly used software for urban flood modeling includes SWMM, PCSWMM, HEC-HMS, HEC-RAS (2D), MIKE URBAN, and InfoWorks ICM, each capable of simulating rainfall-runoff processes and dynamic flood propagation. PCSWMM, in particular, offers a robust and user-friendly GIS-integrated platform that excels in simulating complex urban drainage and flood scenarios with spatial precision. PCSWMM offers a comprehensive and flexible environment for simulating urban hydrology and hydraulics, making it one of the most advanced tools for stormwater and flood management. It is fully GIS-enabled, allowing seamless integration of spatial data such as DEMs, land use, and drainage networks for accurate catchment representation and analysis. The software supports both pipe and open channel flow modeling, enabling realistic simulation of dual drainage systems where surface and subsurface flows interact during heavy rainfall events. With its integrated 1D–2D modeling capability, PCSWMM accurately represents complex flow dynamics, including surface inundation, flow exchange between networks, and floodplain behavior, providing detailed insights for flood risk assessment, infrastructure design, and urban resilience planning.