A conceptual procedure for urban interception and evapotranspiration computation in the SIMGRO model code

The process of urbanization produces radical changes in the nature of the surface and atmospheric properties of a region. It involves the transformation of the radiative, thermal, moisture and aerodynamic characteristics and thereby dislocates the natural solar and hydrologic balances. A model for use in conjunction with the available runoff in order to determine continuously hourly evapotranspiration would be useful to assess water quantity, water quality, and urban climate. The SIMGRO hydrological model has such capacity but could be upgraded for a more accurate description of urbanevapotranspiration. Although The Penman-Monteith equation has a more precise physical meaning, the Makkink formula is preferable for its simplified representation of evaporation that only needs inputs of global radiation and temperature, which are routinely observed. To follow the SIMGRO procedure but with the inclusion of anthropogenic heat flux and consideration of evaporation from prom paved and built-up areas is recommended. Further study is required to compare and validate with the actually measured urban surfaces evapotranspiration. Assessment of the intensity of anthropogenic heat flux, the effect aerodynamic and surface resistance on a number of representative surfaces will help to establish the performance of the model