Numerical simulation of groundwater pollution caused by leakage of urban pipe network: a case study on an interfluve in Shenzhen City

Regarding the underground water pollution resulting from the leakage of urban underground pipe networks, this study selected a specific interfluve in Guangming District, Shenzhen City as the research area and conducted a detailed background investigation of the groundwater environment. Based on the investigation results, we established a hydrogeological conceptual model and a three-dimensional solute transport numerical model by employing the numerical simulation software (Groundwater Modeling System, GMS) to systematically explore the leakage effects of municipal drainage facilities on migration process of groundwater pollutants. The results demonstrated that there existed a pollution risk of groundwater quality in the study area, which was mainly indicated by nitrate, chloride, nitrite, total coliform bacteria and manganese ions, etc. Among them, the nitrate concentration was as high as 25 mg/L. The migration direction of pollutants in the leakage area of the pipe network was influenced by topographic characteristics and generally flows from the northeast to the southwest, with a migration rate of approximately 0. 5 m/d. Additionally, the sensitivity analysis of aquifer parameters indicated that the larger the permeability coefficient of the sediment, the more prominent the degree of groundwater flow and pollutant migration and diffusion, and the broader the diffusion range of the pollution plume. The research findings offer a scientific basis for the prevention and control of groundwater pollution caused by urban pipe network leakage and contribute to facilitating the scientific solution and management practice of pipe network leakage issues in this area and similar environments.