Modeling surface water and groundwater interactions for seepage losses estimation from unlined and lined canals

This study utilized the Slide2 model to simulate surface water and groundwater interactions and estimate seepage losses from unlined and lined irrigation canals. Firstly, it was validated for an unlined canal passing through an unconfined, homogenous, and isotropic infinitely porous depth. Results revealed that the Slide2 model accurately simulated the seepage flow and estimated the seepage losses with R2 = 0.99 and MAPE = 3.6%. Accordingly, the Slide2 model runs 54 scenarios to explore the effect of different groundwater table (GWT) locations below the canal berm, canal berm widths, and liner properties, such as liner hydraulic conductivity and thickness on the seepage losses from unlined and lined irrigation canals. The results concluded that when the GWT was above the canal surface water level (CSWL), the seepage losses tended to be lower, ensuing an inflow to the canal bed and inner side slope. Conversely, when the GWT was below the CSWL, the seepage losses tended to be higher, ensuing an outflow to the surrounding unsaturated soil. In contrast, the GWT did not affect seepage losses from lined canals. Also, a wider berm resulted in fewer seepage losses, while the canal berm was less effective for lined canals. In addition, the results proved the lining ability to reduce seepage losses. Thus, the average reduction percentage of the seepage losses for lined canal scenarios was 99.87%. Also, a thick liner could decrease the seepage losses maximally by 48.52%, regardless of the GWT location below the canal berm.