Diagnóstico físico-conservacionista multitemporal da bacia hidrográfica do Arroio Chasqueiro, Arroio Grande (RS)

Abstract

Watersheds play a crucial role in regulating the water cycle, maintaining biodiversity, and providing essential ecosystem services such as drinking water supply, agricultural irrigation, and power generation. However, the increasing pressure of human activities, such as intensive agriculture and the suppression of native vegetation, has led to significant changes in these study units, resulting in processes of environmental degradation. With a bias of diagnosis and environmental monitoring, this research had as its main objective, to elaborate the Physical-Conservationist Diagnosis (DFC) of the Chasqueiro Creek Hydrographic Basin, in its medium-high course, given the silting problems exist in the Chasqueiro dam. To this end, using geoprocessing techniques, the following parameters were determined: original vegetation cover, current vegetation cover, soil erosion potential, rainfall erosivity, average slope of the land, drainage density and water balance. In order to determine the influence weights of the 7 parameters of the DFC, the multicriteria Analytic Hierarchy Process (AHP) method was used, where the dynamics of land use and occupation are the most important. The results of the research show that the typology of land use had significant changes between the period of 1947 and 2020, starting from a land use focused on extensive cattle raising, followed by silviculture and agriculture with annual crops, mainly soybeans. Finally, 5 classes of conservation/environmental degradation were proposed, based on the slicing of the DFC of the year 2020, where the best results relate to the areas with the recovery of the riparian forest to the worst indices found in the places with agriculture of annual crops in conventional planting and areas with extraction of materials for the construction of the Chasqueiro dam. Finally, it is concluded that the DFC methodology combined with the multicriteria analysis made it possible to identify the degree of conservation/degradation of the study area, pointing out the parameters that most contribute to the current environmental scenario.