摘要
1989年7月26日,贡嘎山东坡南关沟发生了一场典型的冰雪雨水泥石流。它下行30多公里后堵塞大渡河,造成直接经济损失245万元。这场泥石流历时约3小时,持续流动时间2小时。到达大渡河时的流速9.4米/秒,最大流量6768.0立方米/秒,总径流量1716.4万立方米,总输沙量627.0万立方米,残留沉积物总方量310.4万立方米(其中泥石流堵塞大渡河的扇形地方量30.0万立方米),弯道爬高15.5—16.5米。输往堵河扇形地下游方的固体物质方量是扇形地方量的19.9倍,泥石流尾流作用强烈。
At 15-18h.on 26 July, 1989,an ice-snow-melt water and rain debris flow occurred in the Nanguan Gully on the left bank in the Yanzi Valley of the east slope in Mt. Gongga. After flowing down more than 30km,it blocked up the Dadu River and resulted in that the highway of Luding-Shimian was washed out the length of 820m and cutting off the road is more than 9 months. A large highway bridge across the Yanzi Valley from Moxi to the Hailuogou Glacier-Forest Park was destroyed. Direct loss in economy is 2. 45Myuan.The Nanguan Gully with an area of 19. 8 km2 ( 9. 9 km2 is above forest line ) located at 101°54'37'-101°59'11'E, 29°41'23'- 29°44'39'N. In the gully,there are a forset of 2. 1km2, alpine-shrub-grassy marshland about 3. 0km2, mountainous region of precipitous bedrock of 13. 9km2,a glacial area in Dec. 1966 was 0. 8km2 and remained in main channel above forest line. The length of main gully is 9.26km, maximum relative height is 3988m, average longitudinal gradient of main gully bed is 215. 7‰(12°10' ) ,but above the forest line is 443. 3‰ (23°54'). All the gully is granitite,main gully has been developing along the west-north fault, thickness of its till is large.On the basis of site investigation, analysis and caculation, the debris flow went through 3h more or less from beginning motion.to end,but practical time of continuing motion is only 2h more or less. In a distance of over 25km from No. 6 section to No. 1,average velocity is 9. 8m/s, discharge of flood peak changes from 2340-6768m3/s,the maximum weight of a unit volume of debris flow is 2. 0-2. 4t/m3,the runoff total of transporting into the Dadu River is 17. 16Mm3, a total of transporting mud,sand and stone into the Dadu River is 6. 27Mm3. The debris flow appears spasmodically and with viscosity,a nature of its straight advancing is strong,the height of creeping up on the bend way is 15. 5-16. 5m. A total of remaining deposits is 3. 10Mm3. The debris flow body in the process filled all the gully bed on its flow way, occurred sediments of overflowing,decelerating and back flowing.Solid materials of debris flow of blocking up the Dadu River are about 0. 30Mm3,but one of transporting into the Dadu River are 6. 27Mm3. The latter is more 5. 97Mm3 than the former,i, e. the most part of solid materials in the process all transported into the lower reaches below blocking the river fan of the Dadu River. It is called the tail-flow action of debris flow,its sediment is called the tail-flow one. For this reason ,a complete process of debris flow should include 4 links of erosion,transportation,accumulation and tail-flow action.
出处
《山地研究》
CSCD
1992年第2期89-94,T002,共7页
关键词
贡嘎山
南关沟
冰雪
雨水
泥石流
Mt. Gongga, Nanguan Gully, ice- snow- melt water and rain debris flow, tail-flow action
