岩溶塌陷易发区地下水安全开采控制——以珠三角广花盆地城市应急水源地为例

Safe pumping in areas prone to karst collapses: A case study of the urban emergency water source of the Guanghua basin in the Pearl River Delta

以珠三角广花盆地城市应急水源地为例,通过野外现场抽水和室内临界水力梯度试验对比,分析了地下水安全开采的控制条件。结果显示:广花盆地的岩溶塌陷是可通过控制水位降深等方法进行防控的,当地下水开采水位降深控制在9 m以内时,可大幅度降低岩溶塌陷概率。该结果可直接作为企业进行地下水安全开采的控制性指标和政府管理部门安全管控的决策性指标。由于地质条件的差异性,在实际开采地下水过程中,不能机械地依赖单一的地下水水位降深控制指标,应根据抽水影响半径以及各地不同的临界水力坡度分地段控制地下水位降深,或者改变开采方式,以达到充分利用地下水资源的目的。建议在实际抽水期间制订突发灾害预案,加强地下水监测工作,实时掌握地下水和其他影响因素变化动态。

How to realize safe pumping by control in areas prone to karst collapses is an urgent problem for groundwater managers and scientific and technical personnel of the urban emergency water source.Taking the Guanghua basin of Pearl River Delta as an example,this paper presents a comparative analysis of pumping in the field and critical hydraulic gradient tests in the laboratory to determine the control conditions for safe pumping.The results show that the karst collapse can be prevented and controlled by proper choice of the depth of the water level.The probability of sinkhole collapse is greatly reduced when the water level is lower than 9 meters.This result can be directly used as the control index of groundwater safety exploitation by enterprises and the decision-making index of safety management and control by government management departments.At the same time,it is pointed out that due to the differences of geological conditions,in the process of actual groundwater exploitation,it is not possible to rely mechanically on a single control index of groundwater level drawdown.The depth of groundwater level should be controlled according to the influence radius of pumping water and the different critical hydraulic slopes in different regions,or the mining method should be changed to make full use of groundwater resources.It is suggested that emergency disaster plan should be made during the actual pumping period,groundwater monitoring should be strengthened,and groundwater and other influencing factors should be monitored in real time.