الفهرس 
Methods of Measuring Seepage LossesOnly 14 pages are availabe for public view
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Abstract
Canal lining enhances irrigation canal efficiency by increasing discharges, decreasing seepage, and lowering maintenance costs. The liner’s thickness and hydraulic conductivity play anessential role in minimizing seepage losses in lined irrigation canals. In this study, FLOW-3D and Slide2 models were utilized to simulate and estimate the discharge and seepage through irrigation canals, respectively. These models were initially validated and subsequently used to explore three sets of simulation scenarios.The first set of simulation scenarios involved 30 simulation scenarios for lining five reaches of an existing unlined irrigation canal: El-Sont Canal, Asyut, Egypt, with two different materials: Cement Concrete (CC) and CC combined with Low-Density Polyethylene (LDPE) film. In this set, the effect of lining on discharges and seepage losses was explored. Moreover, a cost analysis was conducted to evaluate the feasibility of the selected materials.In the second set of simulation scenarios, the Slide2 model was used to conduct a parametric study to investigate the lining effect on seepage losses from lined irrigation canals when the groundwater table (GWT) level was above the canal bed. In this set,48 simulation scenarios were conducted considering different GWT levels, berm widths, and liner properties.In the third set of simulation scenarios, another parametric study was conducted with a total of 600 simulation scenarios. It aimed to investigate the lining effect on seepage losses from lined irrigation canals when the GWT was below the canal bed consideringdifferentcanal geometries and liner properties. Based on this set, Artificial Neural Network (ANN), and Gene Expression Programming (GEP) were developed to estimate the seepage losses from lined irrigation canals. Moreover, the most effective parameter in estimating seepage losses from lined irrigation canalswas determined.Results showed that FLOW-3D and Slide2 models performed well with a determination coefficient (R2) of more than 0.99 and Mean Absolute Percentage Error (MAPE) of less than10% in calculating the discharges and seepage losses, respectively. Results showed that by lining the canal’s reaches by CC and CC with LDPE film, the dischargeswere increased by 92–97% and 149–156%, and the seepage losses were decreased by 81–87% and approximately 97%, respectively. Moreover, the cost analysis showed that the overall cost of CC with LDPE film was higher by 13.8% than CC.Results from the second and third sets of simulation scenarios showed that when the GWT was above the canal surface water (CSW)level, the seepage losses from lined canals tended to be lower, resulting in an inflow to the canal. Conversely, when the GWT was below the CSW, the seepage losses tended to be higher, resulting in an outflow to the surrounding soil. However, the seepage losses did not depend much on the GWT. The effect of the canal berm was less effective because the liner acted as an impermeable barrier. A thick liner of hydraulic conductivity of less than 0.01 can reduce the seepage losses by more than 96%.ANN and GEP models estimated seepage losses from lined canals very well with a higherPearson correlation coefficient (R) of 0.998 and 0.994 and Mean Squared Error (MSE) of 0.040 and 0.163, respectively. Moreover, the liner hydraulic conductivity had the highest effect on the seepage losses estimation compared to the other investigated parameters, while the side slope was the lowest.Finally, this study underscores the importance of canal lining as a cost-effective means to enhance water conservation and canal efficiency, with the potential to reduce maintenance costs significantly. Moreover, ANN and GEP models were recommended as robust and rapid tools for estimating seepage losses from lined irrigation canals.