桂林毛村地下河流域雨季与旱季定量示踪分析

A quantitative analysis of tracing tests for the Maocun subterranean river basin of Guilin during rainy and dry seasons

以典型岩溶地区广西桂林市毛村地下河流域为例,基于在线高分辨率监测进行雨季与旱季定量示踪试验,精细刻画流域内含水介质特征。根据示踪试验研究及毛村地下河系统内地下水的径流和分布特征,可将毛村地下河系统划分为社更岩、扁岩地下河系统,大冲里-背地坪系统和大岩前落水洞-毛村出口系统。这三个子系统分布于毛村流域的上游和下游,其示踪剂浓度历时曲线为陡升陡降的尖峰,地下管道相对单一,无较大岔道和溶潭发育。各段地下河水动力作用以对流作用为主,且水流一般呈现为紊流流态。雨季流速快、流量较大,平均运移时间短,示踪剂回收率比旱季高。流域中游含水介质相对均匀,无管道发育,地下水主要赋存于溶蚀裂隙。

This paper selected the typical underground river basin in Maocun village of Guilin,Guangxi for quantitative tracer tests in rainy and dry seasons based on online high-resolution monitoring to depict fine characteristics of groundwater aqueous media.According to the tracer test results and groundwater runoff and distribution characteristics,the Maocun underground river system is divided into Shegengyan and Bianyan underground river,Dachongli-Beidiping sub-system and Dayanqian sinkholes-Maocun outlet sub-system,which are distributed in upstream and downstream of the Maocun basin,respectively.The experimental tracer study shows that the breakthrough curves(BTC)are featured by steep upward and steep drop pinnacles,which suggest that the conduits are relatively simple,and have no large turnouts and karst tams developed.Each section of the underground river is generally turbulence which is dominated by convection;the flow velocity and flux in rainy seasons are larger,the average travel time is shorter,and the tracer recovery rates are higher than in dry seasons.The aqueous medium in the middle region is relatively uniform,and has no conduit developed.Groundwater is mainly stored in karst cracks.