青藏高原空间组织的山坡弱化局部化作用定位了热融滑塌的分布

中文摘要 AI 辅助

青藏高原长期的地温升高正在持续且广泛地重塑寒区地貌，并产生了大量局部化和聚集分布的倒退式热融滑塌（RTSs）。然而，在广泛的地温升高背景下，为何RTSs高度局部化和聚集分布这一问题仍未得到完全理解。为了理解和解释RTSs的局部化与聚集现象，我们提出了山坡弱化场（HWF）概念，该场表征了由多种环境条件共同形成的相对山坡弱化状态的空间分布，这些条件包括热状况、水分和土壤性质、地形设置、多年冻土和地下冰条件以及地表覆盖。我们考察了青藏高原七个研究区域内HWF与RTS空间选择性之间的对应关系。在七个区域中的六个观察到了正相关的HWF-RTS对应关系，其中五个区域表现出持续强相关。在这五个区域中，RTSs优先发生在弱化程度更强的山坡上，在弱化程度最强的10%山坡单元内，其发生率为区域背景发生率的3.35至5.09倍。此外，高弱化山坡并非空间孤立，而是在景观中相互关联并连接。包含RTS的山坡单元及其周围山坡的弱化水平高于未记录RTS的山坡单元及其周围区域，且弱化差异随距离增加而减小。这些结果表明，RTSs优先发生在弱化程度更强的山坡上，并在高弱化状态空间连续且连接的区域聚集。我们的发现表明，山坡弱化状态的空间差异有助于解释为何广泛的地温升高所引发的地貌响应在多年冻土景观中高度异质。

英文摘要

Long-term permafrost warming on the Tibetan Plateau is continuously and broadly reshaping cold-region landscapes, and has produced numerous localized and clustered retrogressive thaw slumps (RTSs). However, the question why RTSs are highly localized and clustered under the widespread permafrost warming remains incompletely understood. To understand and explain the RTS localization and clustering, we propose the Hillslope Weakening Field (HWF), which represents the spatial distribution of relative hillslope weakening states jointly formed by multiple environmental conditions, including thermal conditions, moisture and soil properties, topographic setting, permafrost and ground-ice conditions, and land-surface cover. We examined the correspondence between the HWF and RTS spatial selectivity across seven study regions on the Tibetan Plateau. Positive HWF-RTS correspondence was observed in six of the seven regions, with consistently strong relationships in five. In these five regions, RTSs preferentially occurred on more strongly weakened hillslopes, with occurrence rates 3.35-5.09 times the regional background rate within the 10% most strongly weakened slope units. Moreover, high-weakening hillslopes were not spatially isolated but correlated and connected across the landscape. RTS-bearing slope units and their surrounding hillslopes showed higher weakening levels than RTS-unrecorded slope units and their surroundings, and the weakening contrast declined with distance. These results suggest that RTSs preferentially occur on more strongly weakened hillslopes and cluster where high-weakening states are spatially continuous and connected. Our findings show how spatial differences in hillslope weakening states can help explain why geomorphic responses to widespread permafrost warming are highly heterogeneous across permafrost landscapes.

发表机构

• School of Engineering and Technology, China University of Geosciences (Beijing)（中国地质大学（北京）工程技术学院）
• School of Geological Engineering and Geomatics, Chang’an University（长安大学地质工程与测绘学院）

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