Mini-symposium 1: Experimental and numerical modelling of dense fluid flows interacting with the surrounding environment

Organizers: Prof. Sandra Soares Frazao and Dr. Andrea del Gaudio, UC Louvain, Belgium

This session will explore the dynamics of dense fluid flows — such as mudflows, granular avalanches, and transitional regimes — where the interplay between material properties and environmental conditions governs the flow behaviour. Key challenges include characterizing rheological responses (e.g., yield stress, shear-thinning), evaluating the applicability of depth-averaged or multi-phase models, and addressing the complexities of dense mixtures (e.g., segregation, pore pressure effects). Within this context, the scope of the session includes:

• Rheological modelling of dense suspensions and granular flows
• Validity of depth-averaged approaches (e.g., single/two-phase, two-layer formulations)
• Transition mechanisms between flow regimes (e.g., mud-to-granular)
• Environmental interactions (e.g., erosion, deposition, boundary effects)

We welcome contributions than span laboratory experiments, field observations, or numerical simulations, with a focus on bridging gaps between theoretical frameworks and real-world phenomena.

Special Session 1: Turbulence in open channels

Organizer: Prof. Michio Sanjou, University of Kyoto, Japan

Special Session 2: Use of unmanned aerial systems (UAS) in field observation campaigns for environmental hydraulics

Organizer: Prof. Scott Socolofsky, Texas A&M University, USA

Increasingly, unmanned aerial systems (UAS) are being used to conduct or supplement field campaigns in environmental hydraulics.  Observations include still image and video capture using on-board color, infrared, and multi-spectral cameras and observations from various payloads carried by the UAS, including in situ water sampling and LiDAR, among others.  Many important quantitative measures of natural fluid systems can be derived from these observations, notably including topography using structure-from-motion and surface velocity fields, using Doppler analysis of video-captured waves.  This session will host a wide array of hydraulic studies and method development featuring UAS as an observational platform. 

Special Session 3: Sediment transport in vegetated waterways

Organizer: Prof. Priscilla Williams, The University of Iowa, USA

Special Session 4: River confluences: theoretical approaches, field investigations, physical and numerical modelling

Organizer: Prof. Carlo Gualtieri, University of Napoli, Federico II, Italy

Special Session 5: Restoring river connectivity: forecasting tools and monitoring strategies

Organizers: Prof. Rui ML Ferreira; Dr. Isabel Boavida; Dr. Ana Quaresma; Dr. Teresa Alvarez CERIS, Instituto Superior Técnico, Universidade de Lisboa, Portugal

Restoring river connectivity is a global priority. All three spatial dimensions of river connectivity and sustainability (the time dimension) are now being addressed in a systematic way, with normative and planning initiatives substituting the ad-hoc opportunistic framework of the past. The EU's Nature Restoration Law - which targets 25000 km of free-flowing rivers by 2030 - illustrates this paradigm shift.

To be effective, connectivity restoration efforts, particularly those focused on longitudinal connectivity, must be based on a thorough characterization of the pre-intervention system. This includes the characterization of the barriers, a clear definition of the objectives, applying tools to predict post-intervention morphological, hydraulic, bio-chemical, ecological and societal responses, and implementing monitoring strategies to ensure that the river is converging to the envisaged objectives.

This session addresses challenges in a) developing and applying the tools to model the baseline situation and to forecast the morphological, hydraulic, bio-chemical, ecological dynamics of the river post-intervention and b) designing monitoring strategies and developing methods and instruments to measure and track the post-intervention river system, including its hydro-morphological, bio-chemical and ecological strata.

We welcome field, experimental and numerical approaches that may contribute to better characterizing river systems and strengthen our ability to forecast their evolution.

Special Session 6: Hydraulics of urban flooding: multi-scale modeling, prediction, and mitigation of pluvial, fluvial, and compound flood hazards in cities

Organizers: Prof. Humberto Vergara and Dr.  Mohamed Abdelkader, University of Iowa, USA

Urban flooding has emerged as one of the most pressing challenges in environmental hydraulics, driven by intensifying precipitation extremes, expanding impervious surfaces, aging stormwater and drainage infrastructure, and the compounding interactions of pluvial, fluvial, and coastal hazards in densely populated areas. The underlying hydraulic processes such as shallow surface runoff over heterogeneous urban topographies, surcharging and pressurization of sewer networks, dual-drainage exchange between surface and subsurface flow paths, transitions between subcritical and supercritical regimes around buildings, streets, and underpasses, and momentum exchange with vehicles, debris, and urban vegetation, remain difficult to resolve and predict at the spatial and temporal scales relevant to operational decision-making. This session invites contributions that advance the characterization of urban flooding hydraulics through experimental, theoretical, and computational approaches, including high-resolution 2D and 3D hydrodynamic modeling, coupled 1D–2D dual-drainage simulations, laboratory and field investigations of street- and block-scale hydraulics, data-driven and AI-augmented hydraulic models, real-time forecasting and rapid inundation mapping for urban flash floods, and the hydraulic design and performance assessment of nature-based solutions and green–grey infrastructure for flood mitigation. We particularly welcome work that bridges fundamental hydraulic understanding with operational tools and frameworks aimed at enhancing the resilience of cities to extreme rainfall and compound flood events.

Special Session 7: Mixing and transport processes

Organizers:  Prof. Adam Yang, Dalhousie University, Canada, and Prof. Qi Zhou, University of Calgary, Canada

Mixing and transport processes are fundamental to understanding the movement and fate of tracers such as heat, salt, momentum, and biogeochemical substances in natural and engineered fluid systems. This special session brings together researchers from engineering, oceanography, and applied mathematics to discuss recent advances in the theory, observation, and modeling of transport phenomena. Contributions are invited on topics including turbulent mixing, stratified flows, particle dynamics, and transport processes relevant to climate and environmental challenges. The session aims to foster interdisciplinary exchange between communities developing a fundamental understanding of natural aquatic systems and practical engineering solutions for complex environmental flows.