广西布泉地下河发育特征及连通性分析

Development characteristics and connectivity analysis of Buquan underground river in Guangxi Province

为查明广西布泉地下河岩溶发育规律和分布特征,在1∶5万水文地质调查的基础上,对该区地下水水位动态进行长期观测和示踪,研究布泉地下河地表和地下岩溶发育特征,分析布泉河上游和中游各支流间的连通性。该区地表主要为峰丛洼地,溶蚀强烈,地下河管道主要沿断层展布,平面形态呈树枝型,剖面形态呈阶梯型。地下河中下游管道的地下水水位动态对降雨的响应滞后,上游管道及远离管道区的地下水水位动态对降雨的响应敏感。地下河上游和中游地下水平均流速分别为1 166 m/d和1 079 m/d,地下水总体径流速度较快,上游地下水的水力坡度大于中游。地下河上游管道分支较多,地下水连通性较复杂,中游主管道明显,连通性较好。

To detect the karst development characteristics and distribution, long-term groundwater level was observed and groundwater tracer test was conducted based on the integrated 1∶ 50 000 hydrogeological surveys in Buquan underground river of Guangxi Province. Surface and underground karst development chracteristics were summarized, and the connectivity of branches in the upstream and midstream of Buquan underground river was analyzed. The results show that this area is mainly peak cluster and depression landform with strong corrosion. The branch distribution of the underground river is along with faults, with dendritic planar form and ladder-shape profile form. Groundwater level has hysteretic response to precipitation in Buquan midstream and downstream, while it has sensitive response to precipitation in the upstream and the areas away form karst pipeline. The average flow rates are 1 166 m/d and 1 079 m/d for the upstream and midstream respectively, indicating fast groundwater flow. And groundwater in the Buquan upstream has larger hydraulic gradient than that in the midstream. Besides, the upstream has more river branches, suggesting complex groundwater connection. Pipelines in the midstream are clear and show better connectivity.