Abstract. Climate change and demographic pressures are affecting
both the urban water balance and microclimate, thus amplifying urban
flooding and the urban heat island phenomena. These issues need to be
addressed when engaging in urban planning activities. Local authorities and
stakeholders have therefore opted for more nature-based adaptation
strategies, which are especially suitable in influencing hydrological and
energy processes. Assessing the multiple benefits of such strategies on the
urban microclimate requires high-performance numerical tools. This paper
presents recent developments dedicated to the water budget in the Town Energy
Balance for vegetated surfaces (TEB-Veg) model (surface externalisée;
SURFEX v7.3), thus providing a more complete representation of the
hydrological processes taking place in the urban subsoil. This new
hydrological module is called TEB-Hydro. Its inherent features include the
introduction of subsoil beneath built surfaces, the horizontal rebalancing
of intra-mesh soil moisture, soil water drainage via the sewer network and
the limitation of deep drainage. A sensitivity analysis is then performed in
order to identify the hydrological parameters required for model
calibration. This new TEB-Hydro model is evaluated on two small residential
catchments in Nantes (France), over two distinct periods, by comparing
simulated sewer discharge with observed findings. In both cases, the model
tends to overestimate total sewer discharge and performs better under wet
weather conditions, with a Kling–Gupta efficiency (KGE) statistical criterion greater than 0.80 vs.
approximately 0.60 under drier conditions. These results are encouraging
since the same set of model parameters is identified for both catchments,
irrespective of meteorological and local physical conditions. This approach
offers opportunities to apply the TEB-Hydro model at the city scale
alongside projections of climate and demographic changes.
Improvements to the hydrological processes of the Town Energy Balance model (TEB-Veg, SURFEX v7.3) for urban modelling and impact assessment