Statistical Analysis Of The Rule Of Formation And Distribution Of Subterranean Karst Streams, Sichuan Basin And The Surrounding Mountains

There are more than2800Subterranean Streams(SS) in south China, Guizhou,Guangxi, Yunnan, Sichuan, Hunan, Which is a unique form of karst water, is animportant water resource in karst area, and development and utilization ofunderground water resources is one way to alleviate Southwest drought. SS is also thethreaten of underground engineering construction, so researching the rule offormation and distribution of SS, investigating the water quality and water quantity,for the development and utilization of the SS, improvement of the karst area waterdifficulty, and governance engineering problems caused by SS, it is of importanttheoretical and practical significance.This article, which is based on Sichuan basin and the surroundings321:200000hydrological geological maps and reports, and combining with SS involved in theactual karst engineering project, counts the rule of formation and distribution of SS inSichuan basin and the surrounding mountains and the status of the development andutilization, and probes into the controlling factors of formation and distribution of SS.According to the landform, stratum lithology, geological structure and the differenceof hydrogeological condition, Sichuan basin and the surrounding mountains in thestudy area can be divided into five hydrogeological zone,ⅠLongmenshan fault foldmountain, Ⅱ Micangshan-Dabasahn fold mountain, Ⅲ Wushan-Daloushan foldmountain, Ⅳ Emeishan-Washan block mountain, Ⅴ parallelism valley of eastSichuan basin. Through the analysis, this article gets the following conclusion:(1)There are approximately563subterranean streams with a total length of more than2785.69km, total flow of more than173.57m~3/s. There are32SS in ⅠLongmenshan fault fold mountain,131SS in ⅡMicangshan-Dabasahn fold mountain,301SS in ⅢWushan-Daloushan fold mountain,10SS in ⅣEmeishan-Washan blockmountain,89SS in Ⅴparallelism valley of east Sichuan basin, which belongs to theSS high density area. The numbers of SS in Sichuan basin and the surroundingmountains of which the length is less than5km account for about43.34%of the totalSS numbers, and most of the length of SS is short and medium length. The number ofSS in Sichuan basin and the surrounding mountains of which the discharge is less than200L/s account for60.75%of the total, and most of the discharge of SS is mediumand small discharge.(2)There are143SS in Sichuan basin and the surrounding mountains used, andthe numbers of the used SS account for about25.22%of the total SS numbers, and thedischarge of the used SS is about38.99m~3/s, which accounts for about22.46%of thetotal water resources of SS.(3)The numbers of SS in Sichuan basin and the surrounding mountainsdeveloped in Permian System and Triassic System are the most, which account for29.84%and49.02%of the total SS numbers, followed by Cambrian and Ordoviciansystem, which account for11.72%and7.99%of the total. It can be seen that underthe same geological condition, layer thickness, pure quality, good continuity, widedistribution of limestone is more than the dolostone developed SS, and thick layer ofpure carbonate rock group is more than carbonate clip clastic intermediated-acidicdeveloped SS.(4)The formation, distribution and direction of SS in Sichuan basin and thesurrounding mountains is consistent with the regional lineament structure.Longmenshan area, the bearing of trend of SS is NNE direction. Micangshan area, thebearing of trend of SS is EW direction. Dabashan area, the bearing of trend of SS isEW, NW-SE. Wushan-Daloushan area, the the bearing of trend of SS is NE-SW. TheSS mainly locates in the core part of a series of anticlines in Eastern Sichuan fold belt,the bearing of trend of SS is NE, NNE direction. SS is mainly controlled by anticline,and there are283SS developed in anticline, which account for about50.27%of thetotal SS numbers, followed by the syncline, accounting for31.12%of the total, and atlast the fault, only10.83%of the total. According to the relationship between SS andconstruction, the SS can be divided into three types: vertical type, horizontal type andfault type. There are378vertical type, which account for67.14%of the total SS numbers. There are87horizontal type, which account for15.45%of the total. Thereare65fault type, which account for11.55%of the total.(5)Depth of SS is controlled by the local main river(the base level of erosion),and SS are mainly distributed in the horizontal river valley. There are19SSdeveloped in the Yangtze River. The numbers of SS developed in Wujiang River arethe most, which are145and account for25.75%of the total SS numbers, followed theJialingjiang River, which are63and account for11.19%. The numbers of SSdeveloped in Daning River and Yuanjiang River are relatively more, which are56and47, the rest scattered distributing in the vicinity of small tributary of the Yangtze River.Regional topography, which control SS, mainly have three categories, deep canyons,the stratification of terrain and karst valley in eastern Sichuan.