MAPPING OF SMALL RESERVOIRS AND THE ANALYSIS OF ASSOCIATED ENVIRONMENTAL IMPACTS IN THE GUARIROBA WATERSHED, CAMPO GRANDE - MS

Abstract

Throughout history, reservoirs have played a fundamental role in economic development. Dams transform landscapes, however, and create risks of irreversible impacts. Research on the environmental, social, and economic impacts is concentrated on large reservoirs, even though small reservoirs prevail in the landscape. In the Guariroba watershed a large reservoir has been created to supply the city of Campo Grande. Small reservoirs in the watershed have not yet been mapped or their environmental impacts analyzed. This work aimed to map the small reservoirs in the Guariroba watershed, and to analyze the associated environmental impacts, to generate information that can help with the planning and management of anthropic activities. The mapping was performed in a GIS using high spatial resolution satellite images available in World Imagery of ArcMap and historical images from Google Earth. For validation mapping, spectral indices of the dry (2019) and rainy (2020) season, were generated with images from the Sentinel-2A satellite. Sixty-six small reservoirs created by the construction of earth dams in natural watercourses have been mapped, located predominantly in the drainage headwaters, and 119 reservoirs in wetlands, mainly the riverine. Some of the mapped reservoirs did not have stored water, both in the dry and rainy periods. In the drainage headwaters, most of the springs were degraded, with exposed soil, mud sliding and the absence of surrounding forest vegetation. Many reservoirs, used for animal drinking and fish farming, in riverside wetlands are also in the process of environmental degradation.