Lithologic and glacially conditioned controls on regional debris-flow sediment dynamics
Lithologic and glacially conditioned controls on regional debris-flow sediment dynamics
复制标题
岩性和冰川条件对区域泥石流沉积动力学的控制
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
P. Macconi
中科院分区：
文献类型：
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作者：
F. Brardinoni;M. Church;A. Simoni;P. Macconi
泥石流是山区流域内沉积物从坡底向皮埃蒙特沉积扇转移的有效过程。为了进一步了解泥石流沉积动力学在区域尺度上，我们分析了历史（1998-2009年）数据库的泥石流从77个盆地的上阿迪杰省，东北部意大利。通过结合事件体积沉积，高分辨率数字地形，第四纪沉积物测绘的信息，我们能够链接泥石流沉积通量的形态，岩性的变化，和沉积物的可用性。我们发现，流域范围内的比产沙量（SSY）的尺度作为一个反幂函数的流域面积。这一功能受到第四纪沉积物的岩石类型和丰度影响下游沉积物补充速率的方式的强烈控制。当与每个泥石流事件相关的沉积物通量被包含在整个区域的离散空间增量中时，在区域SSY空间中的复杂沉积特征是明显的。也就是说，SSY增加下游高达1平方公里的面积，并开始下降超过这一规模，无论沉积物的可用性。我们建议，这种面积SSY关系的特点是泥石流为主的设置。
Debris flow is an efficient process of sediment transfer from slope base to piedmont depositional fans in mountain drainage basins. To advance understanding of debris-flow sediment dynamics at the regional scale, we analyze a historical (1998–2009) database of debris flows from 77 basins of Alto Adige Province, northeastern Italy. By combining information on event volumetric deposition, high-resolution digital topography, and Quaternary sediment mapping we are able to link debris-flow sediment flux to morphometry, lithologic variability, and sediment availability. We show that basin-wide specific sediment yield (SSY) scales as an inverse power function of basin area. This function is strongly controlled by the way rock type and abundance of Quaternary deposits affect the rate of downstream sediment recruitment. When sediment flux associated with each debris-flow event is subsumed across discrete spatial increments of the entire region, a complex sedimentary signature in the area-SSY space is apparent. That is, SSY increases downstream up to areas as large as 1 km2, and starts to decline beyond this scale, regardless of sediment availability. We propose that this area-SSY relation is characteristic of debris flow–dominated settings.