Experimental and Numerical Modeling of Seepage in Trapezoidal Channels

Abstract

Accurately estimating seepage losses from unlined and lined trapezoidal channels is essential for effective water management, especially in water-scarce regions. This study combined experimental and numerical approaches to evaluate seepage losses, focusing on the influence of channel geometry and liner properties, including hydraulic conductivity (K_L) and thickness (t_L). Firstly, a physical model was constructed, the materials were prepared, and testing procedures were performed to estimate the hydraulic conductivity of the soil and cement mixture. Secondly, five-channel geometries were adjusted in the physical model for unlined and lined experiments. Finally, the Slide2 model results were compared with the experimental data. Results revealed that the Slide2 numerical model accurately estimated seepage losses from unlined and lined trapezoidal channels compared to the physical model with a high determination coefficient (R²) of 0.99 and 0.99 and low root-mean-squared-error (RMSE) values of 2.85 and 0.03 cm³ s^-1, respectively. For unlined channels, the seepage losses increased with larger bed width-to-water depth ratios due to the extended wetted perimeter. For lined channels, lining was ineffective when K_L exceeded 0.01, while a 0.05 increase in t_L reduced seepage losses by 15%. Furthermore, design charts and equations were developed to estimate the seepage losses from unlined and lined channels considering channel dimensions, liner hydraulic conductivity, and thickness.