基于GMS的某垃圾填埋场地下水环境影响预测研究

Study on groundwater environmental impact prediction of a landfill based on GMS

以安徽省向山垃圾填埋场作为研究区,在分析场区水文地质条件的基础上,运用GMS中的MODFLOW和MT3D模块建立地下水流概念模型、数值模型及溶质运移数值模型,并根据取样结果确定污染物因子,模拟正常状况和非正常状况下污染物在地下水环境中的污染路径、污染羽迁移状况和污染物对地下水环境可能造成的影响。研究结果表明:评价区地下水类型主要为岩浆岩类孔隙裂隙水,主要污染源位于老库区及渗滤液处理站位置。正常状况下,在模拟期范围内COD的污染羽中心浓度为1.23~3.0 mg/L,均满足地下水质量标准Ⅲ类水,对地下水环境影响十分有限;非正常状况下,污染物在地下水中沿污染中心向四周浓度逐渐减小,浓度梯度较大,污染物在含水层中沿地下水流方向呈近似椭圆形状运移,污染物在5 a、10 a、20 a与30 a后,运移距离与范围逐年增加,评价区内COD最大超标范围和最大运移距离分别可达125 423.1 m2和640.3 m,表明事故条件下,污染物的泄露会对地下水水质造成污染。建议在填埋场的建设和运营过程中,定期监控水质的变化情况并采取相应控制措施,保证区域水生态环境安全。

Taking Xiangmountain Landfill in Anhui Province as the research area,based on the analysis of the hydrogeological conditions of the site,the conceptual model,numerical model and solute transport numerical model of groundwater flow were established by using MODFLOW and MT3D modules in GMS,and the pollutant factors were determined according to the sampling results. The pollution path of pollutants in groundwater environment under normal and abnormal conditions,the migration of pollution plume and the possible influence of pollutants on groundwater environment are simulated. The results show that the main groundwater types in the evaluation area are magmatic rock pore fissure water,and the main pollution sources are located in the old reservoir area and the location of leachate treatment station. Under normal conditions,the concentration of COD in the center of the pollution plume ranges from 1. 23 mg/L to 3. 0 mg/L in the range of the simulation period,all of which meet the groundwater quality standard of class Ⅲ water,and have a very limited impact on the groundwater environment. Under abnormal conditions,the concentration of pollutants in the groundwater decreases gradually along the pollution center to the periphery,and the concentration gradient is large. The pollutants in the aquifer migrate in an approximately elliptical shape along the direction of the groundwater flow. The migration distance and range of pollutants increase year by year after 5,10,20 and 30 years. The maximum COD exceeding standard range and the maximum COD migration distance in the evaluation area can reach 125423. 1 m2 and 640. 3 m respectively,indicating that the leakage of pollutants will cause pollution to the groundwater quality under the accident conditions. It is suggested that in the process of construction and operation of landfills,the water quality should be monitored regularly and corresponding control measures should be taken to ensure the regional water ecological environment safety.