共同研究報告書
| 研究区分 | 一般研究 |
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研究課題 |
3次元氷河流動モデルを使った氷河湖決壊に関する研究 |
| 新規・継続の別 | 新規 |
| 研究代表者／所属 | 北大低温研 |
| 研究代表者／職名 | 講師 |
| 研究代表者／氏名 | 杉山慎 |
| 研究分担者／氏名／所属／職名 | |||
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1 |
Patrick Riesen | スイス連邦工科大学 | 大学院生 |
| 研究目的 | This project aims to use a three-dimensional glacier flow model to simulate the impact of a glacier outburst flood on glacier dynamics. It is a collaborative work with Patrick Riesen， a graduate student of Swiss Federal Institute of Technology. He is going to work on this project for six month in Institute of Low Temperature Science to complete his diploma thesis under the supervision by Shin Sugiyama. The goal of the project is to reproduce the glacier flow changes observed in Gornergletscher， Switzerland during the outburst events of an ice marginal lake in 2004 and 2006. |
| 研究内容・成果 | A three-dimensional numerical finite-element model for the tongue and confluence area of Gornergletscher has been constructed. The model solves the field equations for a Stokes flow problem and uses Glen's flow law as a constitutive equation. In addition， The model includes basal sliding and a routine for lake water pressure simulation. A number of numerical experiments have been conducted to investigate the ice flow changes observed in the vicinity of a glacier-dammed lake Gornersee. Although the numerical model showed some systematic errors， it was able to produce reasonable results. The investigation of ice dynamics during two lake outburst events was successful and revealed interesting features of the ice dynamics of Gornergletscher. The conclusions of this work are: 1. The influence of the lake water pressure on the ice dynamics in the lake vicinity was clearly identified for the first time by this project. This effect is major and is crucial to incorporate into the numerical model. It must be considered in the analysis of the interaction between Gornersee and the dynamics of Gornergletscher. This may also applicable for ice-dammed lakes in general. 2. The outburst in 2006 affected the subglacial conditions locally. The drainage path of the lake water in 2006 must be constricted to a narrow path off the central flow line rather than an outspread into the subglacial environment. 3. The outburst in 2004 affected subglacial conditions in a broader area than in 2006. The surface flow speed has changed most of the lower reaches from the lake， suggesting that the lake water spread into the bed rather than drained into a localized channel. The first conclusion provides a new insight into the interaction of glacier-dammed lake water and glacier dynamics， whereas the latter two clearly show that a glacier-dammed lake may drain by different mechanisms from year to year. |
| 成果となる論文・学会発表等 | P. Riesen， Investigation of glacier flow during two ice-dammed lake outburst events on Gornergletscher， Valais， Switzerland， by using a three-dimensional numerical model |