Abstract
<title>Abstract</title> <p>The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Most of the landfill sites in developed countries have used Geosynthetic clay liners (GCLs) as landfill leachate barriers to protect the environment. In this article, the simulation of movement of water through the GCL liner, using Hydrus-1D software, was investigated. Twelve different Geosynthetic clay liners, including two types of geotextiles (PP and PET), two types of bentonite (A, B) and three bentonite mass per unit area (4, 4.5 and 5 kg / m2) were tested. Analysis of residual errors, differences between the measured and simulated values, was performed to evaluate the model performance, based on the mean absolute error (MAE), root means square error (RMSE), the coefficient of determination (CD), modeling efficiency (EF) and coefficient of residual mass (CRM). The outputs from the models were compared against the measured infiltrated water and water drained data. Statistical analysis indicated a strong correlation between the simulated and measured trends, with modeling efficiencies of 0.81 and 0.97 for drainage and infiltration, respectively. Additionally, the mean absolute error and root mean square error were 1.29 and 1.45 for estimating the drained water, and 4.23 and 4.71 for the infiltrated water. While the model effectively simulated the overall flow dynamics, a closer comparison revealed a systematic underestimation in the absolute volumes. This discrepancy indicates that although HYDRUS-1D provides a good estimation of the flow process, it does not fully account for the hydrophobicity of the geotextile layers, leading to the observed differences in magnitude.</p>