Analysis of seepage loss from concrete lined irrigation canals in Punjab, Pakistan

ABSTRACT/RÉSUMÉ (ABSTRACT for English and RÉSUMÉ for French) A significant amount of water is lost in canals due to seepage. This could be saved to irrigate barren land. This article presents the measured seepage data by the inflow‐outflow method on seven so‐called concrete‐lined distributary canals in Punjab, Pakistan. A special feature of the inflow‐outflow method is the relatively long lengths of the canal reaches (9 to 5 km), which is the longest one could find in the literature so far. The seepage in canals is also calculated using five empirical formulae. The results show that the Swamee and the Punmia formulae performed admirably with mean percent errors of −20% and + 19% respectively. Moritz formula stood at +53% while Kostiakov scored +158%. The research also proposed a slight modification in the Swamee formula whereby, instead of the canal width, the surface water width was used in the calculation of the dimensionless variable F. This led to a beneficial effect of bringing down the percent mean error from −42% to −20%.