Estudo geoambiental de uma voçoroca em Campo Mourão - PR

Abstract

The urbanization process tends to waterproof soils affecting the hydrologic dynamic directly. These changes on water’s natural paths can result in many problems such as urban erosion. Erosion is the natural soil wearing which can be aggravated by anthropic factors. When this phenomenon occurs in urban areas is generally related to urban drainage that, most of the time, does not follow the city expansion thus becoming inefficient. Urban gullies have become an concerning environmental issue in Brazilian municipalities for they limit urban expansion; moreover, they cause both environmental and social problems. For that reason, the present work objective was to perform a geoenvironmental diagnosis of a gully located in Campo Mourão, PR. In order to realize the study, cartographic material and satellite images were used on the first stage aiming to physically characterize the gully. On the second stage, information about the erosive process was gathered and the surrounding dwellers were interviewed. The following stages were related to causes and consequences of the erosive process and, finally, to suggestions for holding the erosion and improving the degraded area. With the interviews, it was possible to know the history of the erosive process, initiated in the 1970 decade and intensified until the 1980 decade. In the late 1989, a landfilling was performed with construction waste in order to hold the erosion. The causes of the erosion were found to be the urban drainage, the suppression of the permanent preservation area, the landfilling and the creation of a housing development in the surrounding area. All these processes aggravated the erosion process extending its consequences to the nearby area, which has impaired structures and polluted stream inside the gully. Using the information about causes and consequences, some actions for environmental improvement were proposed: division of the pipes that leads water into the affluent stream of KM 119 river so it will receive a lower water volume; the creation of a containment basin using a structure that controls the inflow and outflow of water, which allows a better infiltration and lowers the flow rate; reestablishment of the permanent preservation area along with the suggestion of important species in the recuperation process of the area; and the suspension of the housing development, which is illegal, according to Brazilian legislation.