Stochastic forcing of sediment supply to channel networks from landsliding and debris flow
Stochastic forcing of sediment supply to channel networks from landsliding and debris flow
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DOI：
10.1029/97wr02388
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发表时间：
1997-12-01
影响因子：
5.4
通讯作者：
Dunne, T
中科院分区：
文献类型：
--
作者：
Benda, L;Dunne, T
泥沙流入河网是由暴雨和其他扰动随机驱动的，暴雨和其他扰动在时间和空间上是离散的，发生在地形、堆积性质和从先前扰动中恢复的状态具有自己的空间变异性的地貌上。由此产生的泥沙供应随机场与河网的拓扑结构和输送过程相互作用，以产生表征流域沉积制度的通量和储存的空间和时间模式。这种体制因盆地面积的不同而有系统的变化。我们描述了随机沉积物供应是如何由气候、地形、土工和生物控制产生的，这些控制在不同地区之间有所不同。通过对泥沙由大量浪费提供的景观的应用，说明了一般原理，强迫变量是确定性的堆积层增厚，随机的毁根野火序列，以及在地形和崩塌强度具有空间差异的滑坡源区人口中触发破坏的随机暴雨序列。滑坡在河道中停止或转变为冲刷泥石流，这取决于低阶河道网络的性质。泥沙在这些河道中积累了几个世纪，然后被泥石流转移到下游。对于气候、地形和岩土控制的任何组合，泥沙供应、输送和储存的时间序列随盆地规模而变化。在另一篇论文[本达和邓恩，本期]中，我们使用大量浪费的时间、体积和位置的模拟来研究随机强迫的泥沙供应与通过渠道网络的存储和通量的系统变化之间的相互作用。
Sediment influx to channel networks is stochastically driven by rainstorms and other perturbations, which are discrete in time and space and which occur on a landscape with its own spatial variability in topography, colluvium properties, and state of recovery from previous disturbances. The resulting stochastic field of sediment supply interacts with the topology of the channel network and with transport processes to generate spatial and temporal patterns of flux and storage that characterize the sedimentation regime of a drainage basin. The regime varies systematically with basin area. We describe how the stochastic sediment supply is generated by climatic, topographic, geotechnical, and biotic controls that vary between regions. The general principle is illustrated through application to a landscape where sediment is supplied by mass wasting, and the forcing variables are deterministic thickening of colluvium, random sequences of root-destroying wildfires, and random sequences of rainstorms that trigger failure in a population of landslide source areas with spatial variance in topography and colluvium strength. Landslides stop in channels or convert to scouring debris flows, depending on the nature of the low-order channel network. Sediment accumulates within these channels for centuries before being transferred downstream by debris flows. Time series of sediment supply, transport, and storage vary with basin scale for any combination of climatic, topographic, and geotechnical controls. In a companion paper [Benda and Dunne, this issue] we use simulations of timing, volumes, and locations of mass wasting to study the interaction between a stochastically forced sediment supply and systematic changes of storage and flux through channel networks.