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.