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<p>The 2008 Wenchuan earthquake triggered a vast number of co-seismic landslides, dramatically enhancing sediment supply and initiating prolonged debris flow activity. Focusing on 73 catchments (759&#xa0;km²) in the epicentral region, this study integrates multi-temporal optical remote sensing, debris flow events, rainfall records, and topographic metrics to track long-term debris flow activity, quantify sediment transport processes, and landslide–channel coupling, and examine the evolution of driving mechanisms across subregions. Landslides connected to channels, unconnected landslides, and active channel deposits were manually classified from eight pre- and post-earthquake image sets. Combined with spatial and statistical analyses, the results revealed pronounced spatial and temporal shifts: pre-earthquake activity was concentrated in the north with large-catchment events, whereas post-earthquake activity featured frequent small-scale events peaking in 2010 and reaching maximum magnitude in 2013, followed by quiescence and partial resurgence since 2019. Sediment depletion occurred fastest in the southern subregion, approaching recovery within six years, while central and northern subregions retained midstream deposits, sustaining activity for decades. Spearman’s rank correlation analysis of a 17-year post-seismic dataset (1,241 samples) identified a staged evolution of debris flow driving mechanisms: an early “rainfall-triggered + landslide-supplied” regime (2008–2013) dominant in the south, transitioning to a “channel storage + geomorphic pathway” model (post-2019) with stricter initiation thresholds in the north. Recovery is projected around 2030 in the north and 2048 in the sediment-rich central subregion. These findings elucidate long-term geomorphic responses to major seismic disturbances and underscore the need for adaptive, subregion-specific debris flow mitigation strategies.</p>

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Spatiotemporal trajectories and heterogeneity of post-seismic debris flow activity after the wenchuan earthquake: deciphering decadal-scale evolution and driving mechanisms

  • 期刊论文

  • 发表日期：

    2026年7月17日

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  • Yu Yang,
  • Kaiheng Hu,
  • Chuan Tang,
  • Jiao Wang,
  • Wanjia Guo,
  • Yinghua Cai,
  • Chenxiao Tang,
  • Ming Chen,
  • Ning Li

摘要

The 2008 Wenchuan earthquake triggered a vast number of co-seismic landslides, dramatically enhancing sediment supply and initiating prolonged debris flow activity. Focusing on 73 catchments (759 km²) in the epicentral region, this study integrates multi-temporal optical remote sensing, debris flow events, rainfall records, and topographic metrics to track long-term debris flow activity, quantify sediment transport processes, and landslide–channel coupling, and examine the evolution of driving mechanisms across subregions. Landslides connected to channels, unconnected landslides, and active channel deposits were manually classified from eight pre- and post-earthquake image sets. Combined with spatial and statistical analyses, the results revealed pronounced spatial and temporal shifts: pre-earthquake activity was concentrated in the north with large-catchment events, whereas post-earthquake activity featured frequent small-scale events peaking in 2010 and reaching maximum magnitude in 2013, followed by quiescence and partial resurgence since 2019. Sediment depletion occurred fastest in the southern subregion, approaching recovery within six years, while central and northern subregions retained midstream deposits, sustaining activity for decades. Spearman’s rank correlation analysis of a 17-year post-seismic dataset (1,241 samples) identified a staged evolution of debris flow driving mechanisms: an early “rainfall-triggered + landslide-supplied” regime (2008–2013) dominant in the south, transitioning to a “channel storage + geomorphic pathway” model (post-2019) with stricter initiation thresholds in the north. Recovery is projected around 2030 in the north and 2048 in the sediment-rich central subregion. These findings elucidate long-term geomorphic responses to major seismic disturbances and underscore the need for adaptive, subregion-specific debris flow mitigation strategies.