Impact of the evolution of the urban built-up area on surface runoff in the city of Tandil, Buenos Aires, Argentina: a simulation scenario with HEC-RAS

Abstract

The following article is part of an ongoing investigation that studies and deepens the processes involved in the hydrodynamic modeling of an urban basin. This concept starts from considering the construction of a hydrological model that mainly takes into account the drainage surface and a hydraulic model defined by the characteristics and parameters of the infrastructure that the basin presents.
In the last ten years, hydrological models have been used to assess, understand and analyze runoff dynamics in basin systems, making it possible to predict short and medium-term scenarios from the simulation of events of different intensities and socio-spatial implications.
The objective of this work is to build a mathematical model of flood modeling for the urban basin of the city of Tandil using the HEC-RAS tool. The parameters that define the construction of the numerical model depend on the topography or Digital Land Model, the drainage network, the urban expansion models that established the current territorial configuration of the urban space, the roughness coefficients differentiating the zoning within the city and the rainfall flow determined by its intensity and speed. In this case, the only “input” variable that wasn’t used was the geometric drainage network. From the implemented tool, it was possible to carry out simulations for the years 1996 and 2011. Their analysis allowed us to know the effect of the changes in land cover on the surface runoff, essential to evaluate and recommend management policies and planning of some factors. For example, the treatment, maintenance and extension of the storm drainage network, restrictions on densification in the building, generation of new green spaces that act as infiltration buffers, among other semi-structural measures to current urban planning.