Improvements of the hydrological processes of the Town Energy Balance Model (TEB-Veg, SURFEX v7.3) for urban modelling and impact assessment

Abstract

Abstract. Climate change and demographic pressure are common issues to be considered when conducting urban planning.Local authorities and stakeholders have therefore opted for more nature-based adaptation strategies, which are especially 10 suitable to influence both hydrological and energy processes. Assessing the multiple benefits of such strategies on the urban microclimate thus requires effective numerical tools. This paper presents recent developments of the water budget in the TEB-Veg model (SURFEX v7.3), which allows for a better representation of the hydrological processes of urban subsoil.This new hydrological module has been called TEB-Hydro. The developments studied concern the introduction of subsoil underneath built surfaces, and the processes of: horizontally rebalancing intra-mesh soil moisture, draining soil water via the 15 sewer network, and limiting deep drainage in the aim of achieving a more realistic base flow pattern in the sewer system. A sensitivity analysis is then performed in order to identify the hydrological parameters required for model calibration. The new TEB-Hydro model is evaluated on two small residential catchments in Nantes (France) by comparing simulated sewer discharges to observation findings. In both cases, the model tends to overestimate total sewer discharge and performs better under wet climate conditions, with a KGE statistical criterion greater than 0.80 vs. roughly 0.60 under drier weather 20conditions. Yet these findings remain encouraging since the same set of model parameters are identified for both catchments, irrespective of meteorological and local physical conditions. This approach opens opportunities to apply the model at the city scale with respect to projections of climate and demographic changes.

Between progress and obstacles in urban climate interdisciplinary studies and knowledge transfer to society

“…Efforts have been made recently to simulate the complexity of the urban environment more realistically. Urban vegetation interacting with built‐up elements, water exchanges between atmosphere, surface and soil, as well as building energetics, are new developments that have been recently implemented in urban canopy models. Such configurations now make it possible to explicitly model interactions between all these processes, to more accurately simulate specific adaptation strategies or urban design scenarios, and to enhance diagnoses.…”

Integrated urban services: Experience from four cities on different continents

“…Using a complete vegetation and soil model to represent green roofs, De Munck et al (2018) showed that green roofs would not have a significant effect on air temperature at street level, contrary to ground vegetation and trees. Impacts on hydrology are now included in the model (Stavropulos-Laffaille et al, 2018) and will allow study of the combined UHI-hydrology impacts on Paris and its suburbs. The model developments also permitted testing of implementing alternative urban energy systems; Masson et al (2014b) showed that solar panels could be widely implemented without adverse effect on the UHI (where a slight cooling, of approximately 0.2°C, was simulated).…”