| Abstract: | A one-dimensional, unsteady-state, open-channel model was used to analytically reproduce three lahar events. Factors contributing to the success of the modeling were: (1) the lahars were confined to a channel, (2) channel roughness was defined by field information, and (3) the volume of the flow remained relatively unchanged for the duration of the peak. Manning ‘s ‘n ‘ values used in computing conveyance in the model were subject to the changing rheology of the debris flow and were calculated from field cross-section information (velocities used in these calculations were derived from super-elevation or run-up formulas). For the events modeled in this exercise, Manning ‘s ‘n ‘ calculations ranged from 0.020 to 0.099. In all lahar simulations, the rheology of the flow changed in a downstream direction during the course of the event. Chen ‘s ‘U ‘, the mudflow consistency index, changed approximately an order of magnitude for each event. The ‘ u ‘ values ranged from 5-2,260 kg/m for three events modeled. The empirical approach adopted in this paper is useful as a tool to help predict debris-flow behavior, but does not lead to understanding the physical processes of debris flows. (Author ‘s abstract) |
| Genre: | USGS Numbered Series |
| ProdID: | 28201 |
| Citation Author: | Laenen, Antonius; Hansen, R. P. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | iv, 20 p. :ill., map ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 88-4004 |
| Citation Search Results Text: | Simulation of three lahars in the Mount St Helens area, Washington using a one-dimensional, unsteady-state streamflow model; 1988; WRI; 88-4004; Laenen, Antonius; Hansen, R. P. |
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| Citation Year: | 1988 |
| Type: | citation/reference |
| Text: | Simulation of three lahars in the Mount St Helens area, Washington using a one-dimensional, unsteady-state streamflow model; 1988; WRI; 88-4004; Laenen, Antonius; Hansen, R. P. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1988/4004/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1988/4004/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
