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

Abstract

AbstractIn this study, seepage losses have been determined by the direct inflow–outflow 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 cross‐section 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 m3/s/106 m2. The percentage of seepage losses varied from 2.2% to 8.35%, and seepage losses measured and estimated using empirical equations were comparable.