基于有限差分法的地下水溶质运移模拟:以某垃圾填埋场为例

GROUNDWATER SOLUTE TRANSPORT SIMULATION BASED ON THE FINITE DIFFERENCE METHOD: A CASE STUDY WITH LANDFILL

垃圾填埋场渗滤液中难降解有机物浓度高,且其防渗系统损坏后不易被发现,从而严重威胁周边地下水水质安全。基于MATLAB软件,使用有限差分法求解地下水稳定流和溶质运移模型,并以西部某城市生活垃圾填埋场为例,模拟该垃圾填埋场非正常状况运行对周边潜水含水层水质的影响。研究结果表明:污染物运移方向与地下水流方向一致,在填埋场及其地下水下游方向,COD和氨氮都出现不同程度的超标;垃圾填埋场在非正常状况下运行20年后,COD和氨氮的最大浓度分别为1 039.14,86.62 mg/L,并且在地下水下游方向分别形成0.9621,1.0035 km^2的超标范围,导致水质无法满足GB/T 14848—93《地下水环境质量标准》中Ⅲ类水质标准限值要求。

As it is difficult to find the damage of anti-seepage system of landfill,the landfill leachate with high concentration of refractory organics would be the enormous risk to groundwater.Based on MATLAB software,the steady flow and solute transport models were simulated by finite difference method.Some landfill in west China was chosen as a case to study its influence on unconfined aquifer.The results showed that the contaminate density field was determined by the seepage field of groundwater,and the concentration of COD and NH_3-N were all different levels of exceeding standard at the down-stream direction of groundwater.When the landfill ran for 20 years with abnormal operation,the maximum concentration of COD and NH_3-N would be reach to 1 039.14,86.62 mg/L,respectively;there would be areas as large as 0.9621,1.0035 km^2to COD and NH_3-N,in which the water quality could not satisfy the levelШof＂Quality Standard for Groundwater＂（GB/T 14848—93）.