Storm-triggered landslides in the Peruvian Andes and implications for topography, carbon cycles, and biodiversity
Storm-triggered landslides in the Peruvian Andes and implications for topography, carbon cycles, and biodiversity
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DOI：
10.5194/esurf-4-47-2016
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发表时间：
2016-01-01
影响因子：
3.4
通讯作者：
Malhi, Y.
中科院分区：
文献类型：
--
作者：
Clark, K. E.;West, A. J.;Malhi, Y.
在这项研究中，我们评估了一次罕见的大规模滑坡引发事件的地貌作用，并考虑了其对山地森林生态系统的影响以及安第斯河流域有机碳的侵蚀。众所周知，大暴雨等近端触发因素会导致大量山体滑坡，但在更频繁、规模较小的事件中，这种低频、高强度事件的相对影响尚不清楚。我们使用 Landsat、QuickBird 和 WorldView 卫星图像绘制了 1988 年至 2012 年秘鲁科斯尼帕塔山谷滑坡发生情况的地图，从而制定了 25 年持续时间、年度分辨率的滑坡清单。整个流域的山体滑坡发生率很高，按面积计算，年平均发生率为 0.076%(-1)。因此，平均每约 1320 年就会发生一次山体滑坡彻底翻转山坡，尽管我们的数据表明山体滑坡的发生在空间和时间上存在差异，因此翻转时间可能不均匀。研究期间，滑坡总共从土壤 (80 %) 和植被 (20 %) 中剥夺了 26 +/- 4 tC km(-2) yr(-1) 的有机碳。 2010 年 3 月的一场暴雨占了 25 年研究期间观测到的所有滑坡面积的 27%，并占与滑坡相关的有机碳通量的 26%。年度滑坡面积的近似线性震级-频率关系表明，大风暴对同一时期发生的低频滑坡事件的总和贡献了等效的滑坡破坏面积。然而，与 2010 年风暴相关的山体滑坡的空间分布是不同的。根据降水统计和景观形态，我们假设科斯尼帕塔流域低海拔地区风暴引发的滑坡侵蚀集中可能是长期模式的特征。这些模式可能对亚马逊河流域河流系统的沉积物和有机物质的来源和组成产生影响，并且通过关注定期的生态干扰，对该地区森林生态系统的物种组成产生影响。
In this study, we assess the geomorphic role of a rare, large-magnitude landslide-triggering event and consider its effect on mountain forest ecosystems and the erosion of organic carbon in an Andean river catchment. Proximal triggers such as large rain storms are known to cause large numbers of landslides, but the relative effects of such low-frequency, high-magnitude events are not well known in the context of more regular, smaller events. We develop a 25-year duration, annual-resolution landslide inventory by mapping landslide occurrence in the Kosnipata Valley, Peru, from 1988 to 2012 using Landsat, QuickBird, and WorldView satellite images. Catchment-wide landslide rates were high, averaging 0.076% yr(-1) by area. As a result, landslides on average completely turn over hillslopes every similar to 1320 years, although our data suggest that landslide occurrence varies spatially and temporally, such that turnover times are likely to be non-uniform. In total, landslides stripped 26 +/- 4 tC km(-2) yr(-1) of organic carbon from soil (80 %) and vegetation (20 %) during the study period. A single rain storm in March 2010 accounted for 27% of all landslide area observed during the 25-year study and accounted for 26% of the landslide-associated organic carbon flux. An approximately linear magnitude-frequency relationship for annual landslide areas suggests that large storms contribute an equivalent landslide failure area to the sum of lower-frequency landslide events occurring over the same period. However, the spatial distribution of landslides associated with the 2010 storm is distinct. On the basis of precipitation statistics and landscape morphology, we hypothesise that focusing of storm-triggered landslide erosion at lower elevations in the Kosnipata catchment may be characteristic of longer-term patterns. These patterns may have implications for the source and composition of sediments and organic material supplied to river systems of the Amazon Basin, and, through focusing of regular ecological disturbance, for the species composition of forested ecosystems in the region.