摘要
Abstract
In recent years,researchers have conducted various studies on the classification of groundwater systems and have summarized different methods of this classification.Investigations into groundwater system division and system characteristics have been carried out in several areas of karst mountainous areas in Southwest China.Notably,Guizhou Province has extensively conducted 1∶50000 hydrogeological surveys;however,there has been no research focused on the classification of groundwater systems within the water-bearing system of the Datang Syncline Area in North Guizhou.This area is characterized by multiple bauxite exploration rights,and bauxite is known to be a karst water-filled deposit that is directly replenished by roof water.The karst hydrogeological conditions are extremely complex,which poses certain difficulties for the objective evaluation of the hydrogeological characteristics of bauxite in this area.This study provides an objective evaluation of the regional hydrogeological characteristics by examining the groundwater system in the Datang Syncline Area of North Guizhou.It mainly uses hydrogeological survey data collected from the study area,supplemented by on-site hydrogeological surveys,results of water quality analysis,and long-term observations of groundwater dynamics.This comprehensive analysis aims to delineate the boundaries and characteristics of the groundwater system in the area.
The research findings indicate that the Datang Syncline Area in North Guizhou has a relatively independent groundwater system characterized by relatively complete recharge,runoff,and discharge conditions.This system mainly consists of underground river systems and dispersed discharge systems.The study area is divided into two groundwater systems,namely,the Datang synclinal underground river system and the Luolong anticline dispersed discharge system.The characteristics of each system are described.The water-bearing medium of the Datang synclinal underground river system consists of fissure-cave and cave-pipeline formations.The groundwater depth typically ranges from 50 m to 250 m.Except for the watershed in the southwest,the remaining boundaries are delineated by the aquitard of the Hanjiadian Group within the Zhiliu System.There are 392 surface karst features in the system,including sinkholes,inlets and outlets of underground rivers,and karst funnels.The system is mainly composed of underground river pipelines,with a total of seven main underground rivers.Among these,two larger underground rivers,S17 and S22,are located north of the Luolong River and are considered the main underground rivers in the system.The underground rivers S18,S19,S20,K1,and K2 are developed south of the Luolong River.The Datang synclinal underground river system characterized by a centralized injection supply,concentrated runoff through karst pipelines,and centralized discharge from underground river outlets.In the area north of the Luolong River,groundwater typically flows from north to south,whereas in the southern area,groundwater flows from southwest to northeast.The aquifer medium of dispersed drainage system of the Luolong Anticline is mainly composed of joint fissures.The boundary of the system is delineated as follows:the surface watershed to the northwest,the aquitard of Silurian Hanjiadian Group to the south and east,and the surface watershed to the west.This system is characterized by surface infiltration recharge,joint fissure runoff,and dispersed discharge through springs.The overall direction of groundwater runoff is from north to south.The dynamic changes in water flow are consistent with rainfall variations,and the dynamic changes of groundwater are relatively stable.The chemical type of groundwater is HCO3--Ca2+.Compared with the dry season,the content of Ca2+in surface water during the wet season decreases,primarily due to dilution by rainstorm.The increase of HCO3--is relatively small,mainly because atmospheric precipitation during the rainstorm absorbs high concentration of CO2 from soil and fallen leaves during the surface runoff process,which subsequently leads to chemical reactions.The research findings provide a basis for objectively evaluating the hydrogeological characteristics of bauxite and the regional groundwater resources in the study area.关键词
地下水系统/边界特征/动态变化/大塘向斜/黔北Key words
groundwater system/boundary features/dynamic changes/Datang syncline/North Guizhou分类
地质学
