A relatively new source of gem-quality turquoise is hosted within slates in Zhushan County of China’s Hubei Province.

Flash flooding has become more prominent under climate change, threatening people's life and property. Post‐event investigations of recent events emphasize the role of floating debris, such as vehicles, in exacerbating damage. Few modeling methods and tools have been developed to simulate the full‐process dynamics of floating debris driven by large‐scale flood waves in real world. In this work, a fully coupled model is developed for simulating the full‐process interactive movements of vehicles driven by flash flood hydrodynamics, from entrainment, transport to deposition. The proposed coupled modeling system consists of a finite volume shock‐capturing hydrodynamic model solving the 2D shallow water equations and a 3D discrete element method (DEM) model. The proposed two‐way coupling approach estimates the hydrostatic and hydrodynamic forces acting on solid objects using the water depth and velocity predicted by the hydrodynamic model; the resulting counter forces on the fluid flow are then considered by adding extra source terms in the hydrodynamic model. A multi‐sphere method is further embedded in the DEM model to better represent vehicle shapes. New calculation modules are further implemented to represent the vehicle entrainment, contact and stopping motions. The coupled model is applied to reproduce a flash flood event hit Boscastle in the UK in 2004. Over 100 vehicles were moved and carried downstream by the highly transient flood flow. The model well predicts the hydrodynamics, interactive transport process and the final locations of vehicles. The proposed coupled model provides a new tool for simulating large‐scale flash flooding processes, including debris dynamics.

Urban flooding has become one of the most common natural hazards threatening people’s lives and assets globally due to climate change and rapid urbanization. Hydraulic structures, e.g., sluicegates and pumping stations, can directly influence flooding processes and should be represented in flood modeling and risk assessment. This study aims to present a robust numerical model by incorporating a hydraulic structure simulation module to accurately predict the highly transient flood hydrodynamics interrupted by the operation of hydraulic structures to support object-level risk assessment. Source-term and flux-term coupling approaches are applied and implemented to represent different types of hydraulic structures in the model. For hydraulic structures such as a sluicegate, the flux-term coupling approach may lead to more accurate results, as indicated by the calculated values of NSE and RMSE for different test cases. The model is further applied to predict different design flood scenarios with rainfall inputs created using Intensity-Duration-Frequency relationships, Chicago Design Storm, and surveyed data. The simulation results are combined with established vehicle instability formulas and depth-damage curves to assess the flood impact on individual objects in an urbanized case study area in Zhejiang Province, China.

Flooding increasingly threatens lives and property under climate change and rapid urbanization. Mobile pumping stations offer a practical and cost-effective solution for flood protection in low-lying, densely populated coastal areas. However, previous studies typically used simplified methods to represent pump stations, and few have integrated pump operations into high-resolution simulations of multi-source urban flooding. This study develops a High-Performance Integrated Hydrodynamic Modeling System–Pumping System Model–Flood Impact Assessment Model (i.e., HiPIMS-PSM-FIM) framework to evaluate object-level exposure and quantify the benefits of pumping. In this framework, the PSM is two-way coupled with HiPIMS using a Source Coupling Method to simulate spatiotemporal flood dynamics. The results are then integrated with exposure data through FIM to identify risks and support mitigation strategies. The framework is applied to a multi-source flood in Yuhuan City, Zhejiang Province, China, at 3 m resolution, and shows strong agreement with field surveys. Vulnerability analysis shows Children > Sedans > Adults > SUVs, with educational facilities facing highest risks. Sensitivity results to pumping rates demonstrate that mobile pumping can reduce the affected population by 82% and decrease impacts on key facilities and roads, demonstrating the framework’s robustness and practical value for enhancing urban flood resilience.

Many post-event field investigations of water-related hazards suggest that debris-enriched flow is much more destructive than water flow alone. However, the role of floating objects is rarely considered in the modelling or risk assessment approaches in practice. Existing modelling approaches are mostly focused on a single or limited pieces of debris. The interactions between the flow and multiple floating objects are not well explored and understood, and few modelling tools have been developed with the capability to simulate and predict these complex interactive processes.This work aims to present a two-way coupling numerical model for simulating the full-process dynamics of floating debris driven by flood waves, based on a finite volume shock-capturing hydrodynamic model solving the 2D shallow water equations and a 3D discrete element method (DEM) model. A multi-sphere method (MSM) is introduced to the DEM model to better capture the shape and size of floating objects. The coupled model estimates the hydrostatic and dynamic forces acting on debris directly using the high-resolution water depth and velocity predicted by the hydrodynamic model, efficiently and automatically capturing the interactive dynamics between transient water flow and floating debris. The model is able to simulate the full-process dynamics of floating debris, including vertical displacement, initiation, horizontal transport, depositing, interaction with and impact on structures.After being validated against experiment tests, the model is applied to reproduce a flash flood event in the coastal village of Boscastle, UK, in 2004. During the event, over 100 vehicles were carried by extreme water flow, which blocked and damaged a couple of downstream bridges, changed the pathway and extent of flooding, and finally moved with the flood water to the river mouth. The coupled model well predicts the flood dynamics, transport processes of floating vehicles, and their final locations. Further numerical experiments are caried out to discover and understand the process of floating debris blocking a bridge and the transport process and spatial distribution of different number of floating vehicles during the flood event. This model potentially provides a new and robust tool to more realistically assess flash flood risk and inform planning and design or urban buildings and infrastructure.