Determination of canal seepage loss in Arrah Main Canal: A case study^*

Abstract

In this study, seepage losses have been determined by the direct inflowoutflow method at four selected reaches of the unlined Arrah Main Canal. Grain size analyses of bed materials of all reaches have been carried out, and in situ hydraulic conductivities have been computed using the Guelph permeameter method in all the reaches. The inflow and outflow discharges of all the reaches have been measured using the area-velocity method. The crosssection and velocity profiles at the corresponding canal sections have been measured using an echo sounder and a digital current meter, respectively, upstream and downstream of all the selected reaches. Seepage loss in each reach has been computed using the continuity equation assuming the evaporation losses are negligible. Also, the empirical equations (Molesworth, Offengenden, and Moritz) have been used to calculate the seepage losses in these reaches and compared with the seepage losses determined by the experimental observations. The measured seepage losses in the unlined Arrah Main Canal varied from 3.66 to 13.4 m 3 /s/10 6 m 2 . The percentage of seepage losses varied from 2.2% to 8.35%, and seepage losses measured and estimated using empirical equations were comparable. K E Y W O R D S empirical equations, inflow-outflow method, seepage loss, unlined Arrah Main Canal Résumé Dans cette étude, les pertes par infiltration ont été déterminées par la méthode directe d'entrée-sortie à quatre tronçons sélectionnés du canal principal d'Arrah non revêtu. Une analyse granulométrique des matériaux du lit de tous les tronçons a été effectuée et les conductivités hydrauliques in situ ont été calculées à l'aide du perméamètre de Guelph dans tous les tronçons. Les débits d'entrée et de sortie de tous les tronçons ont été mesurés à l'aide de la méthode Area-Velocity. Les profils de section transversale et de vitesse aux sections de canal correspondantes ont été mesurés à l'aide d'un écho-sondeur et d'un courantomètre numérique, respectivement, en amont et en aval de tous les tronçons sélectionnés. Les pertes par infiltration dans chaque tronçon ont été calculées à l'aide de l'équation de continuité en supposant que les pertes par * Détermination de la perte par infiltration dans le canal principal d'Arrah: une étude de cas

The use of empirical equations for seepage estimation in comparison with observed losses from irrigation canals

“…where: Q s = seepage losses; Q i = inflow discharge at inlet/startpoint of selected reach length of the canal; Q o = outflow discharge at endpoint of reach including discharge of the off-taking outlets within reach. However, evaporation losses in this study have not been considered since the evaporation losses make about 0.3% of total losses reported from the irrigation system and are generally not taken into consideration (Singh et al, 2021;Mutema and Dhavu, 2022).…”

Modified Tractive Force Approach for Sediment Transport Under Bank Seepage

“…(Mutema and Dhavu, 2022). Unlined canals in India are prone to lose a lot of water via seepage as suggested by Singh et al (2021). Hutchings and Petrich (2002) reported in the study that flow lost due to the seepage is 12-20% of flow available in the canal.…”

“…Hutchings and Petrich (2002) reported in the study that flow lost due to the seepage is 12-20% of flow available in the canal. Singh et al (2021) conducted a study to find out seepage loss in the Aarah Main Canal and they observed that loss due to seepage varies in the range of 2.2-8.35% of canal flow. Mutena and Dhavu (2022) in their study enlisted canal shape as one of the factor which affects the seepage loss and they observed that trapezoidal canals exhibit higher seepage losses than the parabolic shaped, U-shaped and elliptical shaped canals.…”