Arcadis was commissioned to support this client’s long-term resilience investment strategy by using catchment-level hydraulic modeling and holistic risk assessment. The work assessed flood risks arising from extreme weather events.
The complexity and regional scale of the project required new techniques for developing a modeling strategy that enabled the concurrent assessment of rainfall, storm surges, and sea wave overtopping.
One of the key challenges of the project was the unique urban landscape of Hong Kong, where extensive footbridges, elevated roads and steep slopes create spatial forms that cannot be readily captured from topographic plans or satellite imagery. Moreover, the city is incredibly dynamic with multiple construction works happening concurrently. This means that various deep excavations were captured in the Digital Terrain Models, creating voids that that would lead to unrealistic flooding predictions if not addressed.
To overcome these challenges the modelling team needed to get creative and adopt digital data from various sources validated by field visits where required. With InfoWorks ICM’s mesh zones, mesh-level zones and seamless integration with most GIS formats, the team was able to replicate complex urban features such as road kerbs and building thresholds at the city scale to ensure confidence in the predictions.
“InfoWorks ICM can easily and effectively integrate all elements of drainage systems and topography, including 2D boundary conditions to incorporate wave overtopping flows.” – Simon Ainley, Principal Modeler.
The modeling team at Arcadis used InfoWorks ICM to develop a high-level screening model of the whole of the Hong Kong region. This was followed by the evaluation of risk at each of the 300+ Mass Transit Railway (MTR) premises – like stations and depots - using network results lines, points and polygons. A number of key stations were subsequently modeled in more detail, including the more precise definition of urban features including kerbs, walls, and buildings.
The team also used InfoWorks ICM’s thematic mapping styles to visually represent the impacts of climate change, specifically the extent of flooding and flooding of station entrances across a large area of Hong Kong.
Ultimately, the model calculated the risk of flooding (2020 and 2081/21 design horizon), while accounting for climate change. It also identified the flood volumes and depths at station access points to aid in the preparation of a progressive risk adaptation and protection plan. This will enable the client to targeted long-term investment to ensure security of service in the face of current and future flood risks.
InfoWorks ICM provided a very efficient top-down assessment of risk for multiple spatial and detail scales, enabling a practical understanding of comparative risk and mechanisms. It also incorporated coastal and rainfall influences within a single modeling environment. In the end, Arcadis used InfoWorks ICM to assist Hong Kong MTR in developing a robust and achievable long-term investment strategy – accommodating for the growing and climate change pressures on the city.