Surface runoff and accelerated erosion in a peri-urban wellhead area in southeastern Brazil

Abstract

Degradation of hydrological conditions can adversely impact water resource quality and quantity. This degradation can generate social and economic losses, including losses for users outside the basin area. Therefore, studies focusing on surface runoff and accelerated erosion processes are needed to enable interventions that address degradation-induced challenges.In the present study, the surface runoff and accelerated erosion potential of the Feijão River basin were presented in charts at a 1:50,000 scale. The Feijão River basin has an area of 243.16 km 2 and is used as the main water source for the city of São Carlos, Brazil. Geoenvironmental attributes, such as substrate, climate, relief, soil, water bodies and land cover and use, were integrated and assessed in a GIS environment, using a multicriteria analysis and weighted sum tool. The results show that a large part of the area (86.12% of the basin) exhibits a low surface runoff potential and a moderate accelerated erosion potential. Accelerated erosive processes are triggered by changes in soil cover and have a direct relationship with the removal of existing vegetation and implementation of anthropogenic activities. In this case, as well as for most of the areas in southeastern Brazil, extensive grazing followed by sugar cane cultivation was the main driving force of erosion, acting as trigger for accelerated erosive processes at the water source area.

Zoneamentos Da Vulnerabilidade Ambiental E Expectativa De Perda De Solo: É Possível Usar a Usle Na Determinação De Vulnerabilidade Ambiental?

“…seres humanos constantemente transformam o ar, solo e água ao seu redor em locais intensamente explorados por atividades econômicas (Aretano et al, 2013;Grecchi al., 2014). A desordenada expansão urbana e agropecuária e a consequente intensificação de processos erosivos do solo, por outro lado, estão associadas com a degradação tanto da quantidade quanto da qualidade de recursos hídricos em bacias hidrográficas (Costa et al, 2018;2019).…”

“…Figura 1 -Localização do município, mancha urbana e captação superficial do manancial de São Carlos na BHRF, drenagens e municípios do entorno (adaptado de Costa et al, 2018).…”

Consideration of land use in the evaluation of erosive processes in gully erosion

“…The land use factor of the area was determined through the analysis of aerial images, also with the help of GIS. The classes of land use and the measurement of the factor adopted by the author were based on the methodology of Costa et al (2018) who conducted a survey of specialists for the study area (São Carlos City -SP). Table 1 shows the classes considered by the authors and adopted by Pascoto (2020).…”

“…This can be explained due to the presence of rubble, domestic waste, and organic matter at the headcut of the gully where the sample was taken for the test. Source: adapted from Pascoto 2020According to Pascoto (2020), the land use was determined considering the methodology of Costa et al (2018), adopting the value 3 (pasture, power transmission lines, and small rural properties) for both features. The author adopted the same category of land use for both situations, based only on aerial photos which visually indicated the same predominant proportion of pasture, in relation to urbanization, within the contribution area of each feature.…”

“…In studies on erosion processes and occurrence, the measurement of land use also occurs in different ways depending on the goal of the study. Costa et al (2018) determined importance for the parameter, through consultation with specialists who took into account the occurrence of erosive processes in the categories determined in the study area in order to map the runoff and accelerated erosion in an urban area.…”