Integrated 1D-2D Hydraulic Modeling for Urban Drainage Systems

Solution Overview

Mathematical modelling of wastewater and stormwater systems was undertaken with SWMM (1D) and Basement (2D), mostly in the downtown area (drainage catchments J&L).[2][3][4] This approach was developed as part of Lisboa's participation as one of three EU validation cities in the RESCCUE project, alongside Barcelona and Bristol, testing innovative tools for urban resilience assessment.[1] The RESCCUE project aimed to deliver a framework enabling city resilience assessment, planning and management by integrating water-centred modelling of strategic urban services performance into a comprehensive resilience platform.[1]

Technical Components

The computational meshes were based on interpolations from up-to-date topography and planimetry data layers.[2] High-resolution computational meshes were applied with more than 500,000 nodes, corresponding to a spatial resolution of four meters.[2] The model was then integrated with the sewer and stormwater networks to dynamically simulate urban stormwater flow and drainage to understand the potential flooding in the region due to storm surges.[2] GIS analysis was used for all the other services and city areas.[3] The modelling focused on the downtown area where old Pombaline sewers from the 18th and 19th centuries are called 'saiméis' and are made of stone, with examples of these infrastructures observed in catchments J and L.[4]

Implementation Details

Mathematical modelling of wastewater and stormwater systems was undertaken with SWMM (1D) and Basement (2D), mostly in the downtown area (drainage catchments J&L).[5][6][7] The implementation occurred within the RESCCUE project framework, which assessed urban resilience from a multisectorial approach for current and future climate change scenarios including multiple hazards.[1] The effects of multiple hazards and interdependencies in the city were also studied, namely flooding/mobility, flooding/energy and flooding/waste.[3] For different scenarios, considering both the current situation and the future with climate change, flooding exposure and vulnerability of each urban service were characterised, and the respective hazard maps were produced.[3]

Benefits and Impacts

What-if scenarios generated by the flood resilience models based on the Digital Twin models are estimated to avoid 20 floods in the next 100 years and save more than EUR 100,000,000 in damaged infrastructure and loss of livelihoods.[2] The hazard maps produced through this modelling approach may be visualised through the project's online toolkit.[3] The high-resolution computational approach with more than 500,000 nodes enables detailed understanding of potential flooding patterns at a four-meter spatial resolution.[2]

Climate Adaptation Relevance

This modelling system addresses flooding risks from storm surges by dynamically simulating urban stormwater flow and drainage patterns.[2] The approach evaluates both current conditions and future climate change scenarios, enabling characterisation of flooding exposure and vulnerability across urban services.[3] The integration of multiple hazard assessments, including flooding interactions with mobility, energy, and waste systems, provides comprehensive understanding of climate-related interdependencies.[3]