四川九寨沟县关庙沟泥石流及其防治对策

关庙沟为嘉陵江上游支流白水江右岸的一条支沟,位于四川九寨沟县城区,曾多次发生过严重的泥石流灾害,直接威胁县城和九寨沟旅游环线公路的安全。该沟泥石流具有容重大(2.20t/m~3)、搬运固体物质粒径粗、固体物质以沟岸滑坡和沟床堆积物补给为主等特征。本文分析了该沟泥石流的形成、流体性质、类型等基本特征,预测灾害的发展趋势,提出泥石流减灾防灾对策。

Debris Flow Disaster and Its Control in Guanmiao Gully in Sichuan Province

Guanmiao Gully, located in Jiuzhanggou Town, is one of the first tributaries of the Baishuijiang River of Jialingjiang River system. Guanmiao Gully is a representative debris flow gully in the mountain of Sichuan Province. It has a drainage area of 14. 3 km2, and a total length of 8. 20 km. Geological, geomorphological, and climatic features are presented in this paper. The drainage develops in the eastern edge of the Minshan mountain area, and in the northern edge of Longmenshan mountain area, where the precipitation is very concentrated from May to September accounting for 75% of the year, the maximum daily precipitation is 51. 3 mm. Therefore, the composition of landform, geology and rainstorm provides favourable conditions for debris flow on July 28, 1984, which was disastrous excited in this Gully. In this disaster, 26 persons died, 40km highway was damaged, 35925m2 houses were destroyed, farmlands were covered with stone, mud and silt. The debris flow with the charactersistics, such as rush occurrence, short duration, high density, strong impact, was triggered by a storm in Guanmiao ravine, It affected the city, towns, villages and road in front of the hill, and destroyed landscape on the hill. Potential hazards are still existing in the gullies. The major characteristics of debris flow are as follows: (1) The fluid belongs to viscous, the unit weight is 2. 22 t/m3; (2) Solid state material composing fluid are thick; (3) The majority of solid material stems from landslide and gully-bed deposits; (4) Low frequency, the period of a large-scale debris flow occureence is about 50-70 years. Debris flow has two development tendencies in this gully, if unreasonable activities of human cease, and a comprehensive control measure work, debris flow will become weak. Four engineering plans for disaster relief have been put forward. The optimal plan has been recommended based on the comparison. The comprehensive planning for controlling the debris flow consists of 2 check dams, a 485 m-long drainage grooves, 10 submerged dims and planting, The action is of great significance for improving environment and protecting personal. By adopting the control, land use planning, urban and rural development, and environmental conservation, integrating debris flow control will have positive impact on economic and social development as well as local environment preservation.