Using Finite Difference Approach to Model Nitrate Contaminant Transport to a Contaminated Well

Many developing countries, and some developed countries, experience groundwater pollution. This problem is increasing in all areas of the world including Lebanon. Many factors have contributed to the groundwater pollution problem in Lebanon, some unique to the area (e.g., refugees, reliance on private wells) and others similar to those around the world (e.g., climate change, increased use of fertilizers). Efforts are being made to identify the contributing factors and find solutions. This study attempts to determine the nitrate contaminant transport to a contaminated public well in Chadra, Lebanon. MODFLOW software, a U.S. Geological Survey modular finite-difference flow model, is used to model the polluted well with its surrounding pollutant sources. Samples are collected from the well and tested in the laboratory using ASTM standard methods. A 3D model of the well was created and used to study the effect of porosity, time and well abstraction rate on the contaminant's path. Findings showed that the distance is inversely proportional to porosity and proportional to time and abstraction rate. Moreover, the software model results matched testing outcome of the nitrate concentration detected in the subject well.