Landslide-driven drainage divide migration
Landslide-driven drainage divide migration
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DOI：
10.1130/g39916.1
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发表时间：
2018-05-01
期刊：
影响因子：
5.8
通讯作者：
Li, Gen
中科院分区：
文献类型：
--
作者：
Dahlquist, Maxwell P.;West, A. Joshua;Li, Gen
流域分水岭的迁移重组了流域，重新分配了侵蚀能量，并促进了构造、侵蚀和气候之间的反馈。然而，人们对鸿沟迁移的条件和发生这种迁移的时间尺度知之甚少。通过将渠道与陡峭地貌中的山坡连接起来，滑坡预计将在分水岭迁移和景观演变中发挥核心作用。在这项研究中，我们研究了由三次事件(两次地震和一次热带气旋)引发的山体滑坡，试图洞察对分水岭迁移的控制。在引发的大约100,000次滑坡中，我们绘制了365次导致分水岭迁移的地图，导致受滑坡影响的盆地之间的总交换量从类似的2千米到82,000千米(2)。通过应用几种基于河道形态的分水岭稳定性指标，我们使用我们的分水岭迁移数据库来测试滑坡在河道和分水岭之间耦合中的作用。我们发现，在单个滑坡发生事件的时间尺度上，流域之间的面积增减模式与从渠道度量推断的向稳定状态发展的景观是一致的。我们还提出了一个量度来量化分水岭迁移、面积交换和事件对地形稳定状态的贡献。将我们的分析局限于主要流域分水岭，并利用台湾地区的重现间隔和地形演化率的估算，我们计算出，大型台风引发的滑坡至少占台湾南部迈向稳定状态的12%-15%。
Drainage divide migration reorganizes river basins, redistributing erosive energy and contributing to feedbacks between tectonics, erosion, and climate. However, the conditions governing divide migration and the time scales on which it occurs are poorly understood. By connecting channels to hillslopes in steep landscapes, landslides are expected to play a central role in divide migration and landscape evolution. In this study, we examine landslides triggered by three events (two earthquakes and a tropical cyclone), seeking insight into controls on divide migration. Of the similar to 100,000 landslides triggered, we mapped 365 that caused a divide to migrate, resulting in a total exchange of similar to 2 km(2) between basins from similar to 82,000 km(2) affected by landsliding. By applying several proposed metrics for divide stability based on river channel morphology, we use our database of divide migrations to test for the role of landslides in coupling between channels and divides. We find that, at the time scale of a single landslide-generating event, patterns of area gain and loss between basins are consistent with landscapes progressing toward steady state, as inferred from channel metrics. We also propose a metric to quantify divide migration, area exchange, and the contribution of an event toward topographic steady state. Restricting our analysis to the main drainage divide, and using estimates of recurrence interval and the rate of topographic evolution in Taiwan, we calculate that landslides triggered by large typhoons account for a minimum of 12%-15% of southern Taiwan's progress toward steady state.