Anthropogenic forcing of gully sidewall erosion: balancing natural susceptibility and land use management in areas with Cuestas relief under tropical climate dynamics in southeastern Brazil

Gully erosion is a complex and multicausal process influenced by climatic conditions, soil properties, and land use/land cover (LULCC). In Southeastern Brazil, especially in the State of São Paulo, the Cuesta relief under a tropical climate contains numerous gullies within cattle pastures. The interactions among these factors remain poorly understood. This study aimed to explain gully sidewall erosion by (i) identifying the role of the tropical climate and soil properties (grain size, soil penetration resistance, and infiltration rates) on erosion processes, (ii) assessing the role of cattle grazing, and (iii) evaluating the effectiveness of ongoing restoration measures. We applied three complementary approaches: monitoring gully sidewalls over a three-year period, comparing contrasting LULCC types, and analyzing soil physical properties during wet and dry periods. Statistical techniques were used to examine the relationships among soil physical properties and erosion patterns. The results show that the headcut sectors are particularly vulnerable, functioning as preferential entry points for surface flows during wet periods. Cattle grazing intensifies sidewall erosion, whereas afforestation reduces it, although not fully preventing degradation. Cattle trampling and fine grain size can increase soil penetration resistance and reduce infiltration rates, rendering specific sectors prone to erosion. Despiste spatial limitations, these findings highlight the importance of targeted soil management and restoration strategies to limit gully expansion and conserve soil resources. They also emphasize that continuous monitoring of soil and vegetation properties is essential to support adaptive management and enhance landscape resilience.