Abstract:【Objective】Clarifying the historical trajectory of soil erosion in karst regions and investigating the mechanisms of soil and water loss are of great significance for evaluating the ecological restoration potential of regional reforestation and advancing soil and water conservation efforts. While substantial research achievements have been made in soil erosion studies over the past five decades, the evolutionary mechanisms of soil erosion in Chongqing""s karst areas over the past century remain unclear. 【Method】This study focused on a mature Tiankeng in Banxi Town, Youyang County, Chongqing Municipality, located in a typical karst region of Southwest China. The research employed the radioactive nuclide dating methods of ¹³⁷Cs and ²¹⁰Pb to establish a chronological sequence of the sediment profile within the Tiankeng. By integrating sedimentary environmental indicators with historical records of human activities, the soil erosion history over the past century in the Xiaojiazhai karst sub-catchment (where the Tiankeng resides) was reconstructed. In parallel, the findings were compared with research results from the Zhongliang Mountain karst depression and Changjiawa depression in Chongqing to investigate the impacts of human activities on soil erosion processes in the karst areas of Chongqing Municipality at a centennial scale. 【Result】The results indicated that the soil erosion history in the study area could be divided into three phases: 1897–1955, 1955–1965, and 1965–2023. Over the past century, the sedimentation rate and average erosion modulus in the sub-catchment exhibited significant variations. During 1955–1965, the sedimentation rate and erosion modulus reached 2.30 cm·a⁻¹ and 1109 t·km⁻²·a⁻¹, respectively, which were markedly higher than those of the other two phases. Comparative analysis with soil erosion histories from the Changjiawa Depression in Wushan County and the Zhongliang Mountain Depression in Chongqing revealed that sedimentation rates and erosion moduli in karst sub-catchments of Chongqing over the past century followed a consistent pattern of initial increase followed by decline, with peak erosion modulus values occurring in the late 1950s. To further assess the influence of precipitation on erosion modulus, a correlation analysis between precipitation data and erosion modulus in Youyang County was conducted. The results demonstrated no significant correlation (R² = 0.0059) between precipitation and erosion modulus over the past century, suggesting that precipitation variation likely did not dominate the pronounced changes in soil erosion within the Tiankeng area during this period. Also, the high erosion modulus phase (1955–1965) coincided with extreme drought events and large-scale deforestation in the late 1950s, coinciding with a drastic reduction in forest coverage during this period. Additionally, abrupt increases in δ¹³Corg values and magnetic susceptibility within the sediment profile provided further evidence of the combined impacts of extreme drought and intensive human activities on environmental degradation. These findings suggest that extreme drought and deforestation during this period were critical drivers of intensified soil erosion in Chongqing""s karst regions. 【Conclusion】The study highlights that regional environmental changes caused by intense human activities far exceeded those resulting from natural conditions and thus, provides novel insights into century-scale soil erosion processes in Chongqing’s karst catchments. The findings enhance understanding of regional desertification mechanisms and inform targeted strategies for soil-water conservation.