Stability of Sheet Flow of Water Beneath Temperate Glaciers and Implications for Glacier Surging
Stability of Sheet Flow of Water Beneath Temperate Glaciers and Implications for Glacier Surging
复制标题
温带冰川下水层流的稳定性及其对冰川涌动的影响
DOI：
--
复制
发表时间：
1982
影响因子：
3.4
通讯作者：
Joseph S. Walder
中科院分区：
文献类型：
--
作者：
Joseph S. Walder
摘要本文提出了一个温带冰川下薄层水流稳定性的数学模型。增强的粘性热耗散在厚的部分的片材趋于使片流不稳定，不稳定性增加的片材厚度和压力梯度的增加。然而，当冰川滑过河床上的突起物时，早期的河道可能会被破坏。准稳定面流可能适用于厚度达几毫米的面流，特别是在冰川表面坡度相对平缓、滑动速度从中等到高速的情况下。这样的水席可能会在一定程度上减少冰川床的有效粗糙度，但可能不足以允许浪涌启动。此外，冰床中存在大量充满水的洞穴，这将减少冰床的厚度，并降低水对冰床的“润滑”程度。
Abstract A mathematical model is presented for the stability of sheet flow of water beneath a temperate glacier. Enhanced viscous heat dissipation in thick parts of the sheet tends to make sheet flow unstable, the instability increasing as sheet thickness and pressure gradient increase. However, incipient channels may be destroyed as the glacier slides over protuberances on its bed. Quasi-stable sheet flow may be possible for sheets up to several millimeters in thickness, especially beneath glaciers that have relatively gentle surface slopes and slide at moderate to high speeds. Such water sheets may somewhat reduce the effective roughness of glacier beds, but probably not enough to allow surge initiation. Furthermore, the presence of numerous water-filled cavities at the glacier bed will tend to reduce the sheet thickness and lessen the degree of “lubrication” of the glacier bed by the water sheet.