Multiscale modelling of a (semi-)urbanised catchment with the help of the Multi-Hydro model

The fully distributed and scalable model Multi-Hydro (MH) enables a high resolution hydro-dynamic modelling of surface flow, infiltration, sewer flow and their interactions, including the retroaction of sewer overflows on surface. Its modular structure simplifies the introduction of new numerical engines, e.g., to simulate air quality or microclimate, to test implementation methodologies and/or develop user-friendly tools for urban management and design, going well beyond the flood control purposes.

Several extensions of MH were recently developed and greatly widened its functionalities. To give an example, they could be used for modelling and visualisation of climatic stress in the built environment and the resulting outdoor comfort, with an identification of cool corridors and climate safe paths.

By considering the high-resolution distributed rainfall, but also the layout of impervious and green areas on a range of representative streetscapes of a (semi-)urbanised catchment, this presentation addresses the questions on efficiency of additional ecosystem performances related to water availability (as cooling effect). Several scenarios were considered regarding possible adaption strategies, with a particular emphasis on  a multiscale analysis of :

• the confrontation between models and experimental data;
• the model induced structural choices and resulting limitations, in particular on the relevant space-time scales, as well their capacity to represent the extreme heterogeneity of the fields;
• the modelling of environmental variability across scales rather than at a given scale.