典型岩溶地下河系统暴雨条件下水文水化学动态变化研究

A study of the variations in hydrology and hydrochemistry under the condition of a storm in a typical karst subterranean stream

利用HOBO小型自动气象站、WGZ21型光电数字水位计和CTDP300型在线水质监测仪,对典型岩溶槽谷地下河系统暴雨条件下水文水化学动态变化进行了连续监测,运用WATSPAC软件计算方解石饱和指数(SIc)和CO2分压(PCO2)。分析了降雨过程中,地下河系统水文水化学动态变化特征。结果表明:在降雨过程中,地下河系统总体以稀释效应为主,对降雨的响应速度快。其中,地下河入口水化学变化受降雨稀释效应和外界环境因素共同影响,变化复杂。出口水化学变化以稀释效应为主,较入口规律。强降雨初期主要由来自中下游岩溶裂隙和洼地对地下河管道的快速补给;降雨后期和降雨过程结束后主要由来自上游岩口落水洞的注入补给。青木关流域岩溶发育程度高,岩溶管道流畅通性良好。强降雨形成的短时地表产流集中注入、降雨入渗经裂隙的快速补给对地下河水质的好坏造成直接影响。

HOBO automatic weather station,WGZ21 Photoelectric digital water table gauge and CTDP300 on-line water quality analyzer were set up to monitor hydrology,hydrochemistry and precipitation at the catchment of a subterranean stream during a storm.According to the liner relationships,the saturation index of calcite（SIc） and CO2 partial pressure（PCO2） were calculated with the WATSPEC program.The hydrochemical variation in the subterranean stream was analyzed.Results show that hydrochemical variation in a subterranean stream was controlled by dilution effect and also responded to the rainfall rapidly.The hydrochemical variation of inlet was impacted by the rainfall events and the factor of environments.The hydrochemical variation of outlet was controlled by dilution effect,the variation was more regular than inlet of the subterranean stream.In the beginning of the storm,the main recharges of subterranean came from karst fissure and depressions.After the rain,the main recharges came from surface flow through the swallow holes.Rainfall went rapidly into the subterranean stream through depressions and karst fissures.As a result,the recharges from infiltration have a direct impact on water quality of the subterranean stream.