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冰川冻土 ›› 1989, Vol. 11 ›› Issue (2): 148-160.

• 研究论文 • 上一篇    下一篇

西藏波密冬茹弄巴的冰雪融水泥石流

吕儒仁, 李德基   

  1. 中国科学院成都地理研究所
  • 收稿日期:1987-01-13 修回日期:1987-11-02 出版日期:1989-05-25 发布日期:2012-04-26

Ice-Snow-Melt Water Debris Flows in the Dongru Longba (Gully) Bomi County, Xizang (Tibet)

Lu Ruren, Li Deji   

  1. Chengdu Institute of Geography, Chinese Academy of Sciences
  • Received:1987-01-13 Revised:1987-11-02 Online:1989-05-25 Published:2012-04-26

摘要: 以积雪融水为主的冰川泥石流通常在夏初爆发,主沟中下游的崩塌、滑坡堵沟是固体物质的重要来源之一。本文记述了一场典型的冰雪融水泥石流过程及危害。讨论了冬茹弄巴冰雪融水泥石流趋势是在减弱,川藏公路通过该沟方案可采取防御中等规模泥石流修建半永久性桥的对策。从分析波密地区水热组合变化得到了预报中长期冰川泥石流发生的一个气候判据。

关键词: 冬茹弄巴(沟), 冰雪融水泥石流, 水热组合变化

Abstract: The Dongru Longba, with a drainage area of 23.74 km2, and 80 km from Bomi County, Tibet, is located along the Chengdu-Lasa Highway. There are 2.06 km2 of modern glacier and snow basin. Debris flows induced by ice-snow melt water occurred repeatedly in the 1960s-1970s. The Yupu Zangbu River section of Palong Zangbu River was blocked up and changed to a lake, which destroyed the roadbed of the Chengdu-Lasa Highway.Topography in the Dongru Longba is rugged, mountain slope is precipitous, gully bed gradient is greater. The maximum amplitude from peak to valley in basin is 2500 m, average gradient of mountain slojje is above 33°, average gradient of the gullybed is 214.0%. The loose meterials storage in the basin is about 179.6 million m3. The annual average temperature in the basin is about 7℃, the annual precipitation is about 750 mm. Because of the influence of ice-snow melt water, the daily amplitude of discharge in summer is up to 3.A ice-snow-melt water debris flow occurred in the Dongru Longba on June 12, 1975, velocity below the outlet is 8.1 m/s, discharge is 562.1 m3/s, total quantity of the debris flow deposit is 12.2 thousand nv, 290 m of the Chengdu-Lasa Highway was dashed and buried, 1.5 km of the highway roadbed was destroyed by dam burst flood, it had been restored after a half month.After having analyzed debris flows in different scales in history, authors recongnize that the debris flow development tendency in the Dongru Longba is weakening, so it is suitable that bridge opining scheme of the Chengdu-Lasa Highway through the gully can deal with middel scale debris flows.The middle and long range forecast of ice-snow-melt water debris flow in the southeast Tibet, is a extremely complex problem, it has been proved from analyzing that in a period of ice-snow-melt water debris flows, relative wet-warm, wet-cold and dry-warm years are decreasingly favourable to apperance of this phenomenon, but indry-cold years, it nardly occurs. The detail explanation is that if precipition in earlier pe riod (a year or years ago, winter and spring etc.) is plentiful, the atmospheric temperature in later stage rises suddenly (0.6-1.2℃ from year to year) or temperature in spring and summer leaps up, it will first cause ice-snow-melt water debris flow taking snowmelt water as main water source, after this, lead to appearance of glacier debris flows taking ice-snow-melt water as major water source; suppose long or short rain process appears, it will quickly accelerate evolution of this nature process. This is only weather criterion for middle and long range forcast of ice-snow-melt water debris flows by authors. It will be tested in the coming practice.

Key words: Dongru Longba (Gully), ice-snow-melt water debris flow, water-heat constitution change