Hydrological impacts of urban expansion in a Brazilian metropolis - Case study of the Vargem das Flores reservoir catchment

This paper aims to evaluate the hydrologic impacts of urban expansion in a peri-urban catchment that drains into a reservoir of the drinking water supply system of Belo Horizonte Metropolitan Region in Brazil. Despite the metropolitan interest and efforts in protecting the catchment, a recent change in zoning ordinances allowed urban expansion in the area. To evaluate the potential hydrological impacts of this land use regulation change, scenarios of urban expansion were conceived and simulated in the model Dinamica EGO. The Storm Water Management Model (SWMM) was employed to assess potential hydrological impacts of land use change projections. Observed precipitation and water level data of the reservoir were used to calibrate and validate the hydrological model. Results confirm the impacts on several catchment hydrological processes following the progressive urban expansion in the area, particularly on volumes of infiltration, groundwater flow and runoff, increasing peak flows and flooding downstream the reservoir.