Spontaneous channelization in permeable ground: theory, experiment, and observation
Spontaneous channelization in permeable ground: theory, experiment, and observation
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透水地面的自发渠道化：理论、实验和观察
DOI：
10.1017/s0022112004007931
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发表时间：
2003
影响因子：
3.7
通讯作者：
D. Rothman
中科院分区：
文献类型：
--
作者：
N. Schorghofer;B. Jensen;A. Kudrolli;D. Rothman
被自然排水通道有节奏地分割的景观存在于各种地质和气候环境中。这种景观的特点是通道之间的横向间距的长度尺度。我们观察到一个小规模的版本，这个过程中的形式海滩细沟和重现渠化在桌面渗流实验。在海滩以及在实验中，通道是由表面流自发切割的，但是一旦开始，它们由于地下水的出现而生长。现场观测和实验表明，这一过程可以用水流通过具有自由形状地下水位的均匀多孔介质来描述。根据这一理论，地下水位的微小变形会放大流入河道的流量，并导致进一步增长，我们称之为“温特沃斯不稳定性”。地下水的盗采可能发生在远大于河道宽度的距离上。信道间隔随时间变粗，直到信道达到其最大长度。
Landscapes that are rhythmically dissected by natural drainage channels exist in various geologic and climatic settings. Such landscapes are characterized by a length-scale for the lateral spacing between channels. We observe a small-scale version of this process in the form of beach rills and reproduce channelization in a table-top seepage experiment. On the beach as well as in the experiments, channels are spontaneously incised by surface flow, but once initiated, they grow due to water emerging from underground. Field observation and experiment suggest the process can be described in terms of flow through a homogeneous porous medium with a freely shaped water table. According to this theory, small deformations of the underground water table amplify the flux into the channel and lead to further growth, a phenomenon we call ‘Wentworth instability’. Piracy of groundwater can occur over distances much larger than the channel width. Channel spacing coarsens with time, until channels reach their maximum length.