The objectives of this study were to determine the water delivery losses from earth canal irrigation systems and to evaluate the conveyances. Five irrigation districts near Ansung, Kyungki-do were chosen to be the study areas. They are Yidong, Madum, Yongdam, Gosam, and Keumkwang. For those districts, field measurement for discharge, infiltration rates, canal geometry, and watergrass density were made during irrigation periods in 1983 and 1984. The results from field data can be summarized as follows: 1. Infiltration losses per unit area of wetted perimeter at the mains and at the laterals in Keumkwang district were 3.333×10^-7 and 9.956×10^-6㎥/s/㎡, respectively. In Gosam district they varied from 1.114×10^-6㎥/s/㎡ to 5.833×10^-6㎥/s/㎡ respectively. Infiltration losses per unit length of canal at laterals were generally more than those at the mains in those districts. 2. Infiltration losses increased with soil permeability at the measured points. The results suggested that the infiltration losses of a canal depend much upon the soil property. 3. The average water delivery losses per unit area of wetted perimeter from Songduk, Mogok, Yongdam, Antak, and Keumkwang canals were 7.200×10^-5㎥/s/㎡ at the mains, and 9.496×10^-5㎥/s/㎡ at the laterals. And the average water delivery losses per unit length of canal at the mains, laterals, and ditches were 2.414×10^-4, 1.649×10^-4, and 4.170×10^-6㎥/s/m respectively. 4. The average rates of water losses from Songduk, Mogok, Yongdam, Antak, and Keumkwang canals were 21.25% at the mains, 31.15% at the laterals, and 6.97% at the ditches. 5. Operational losses per unit length of canal were 4.282×10^-4㎥/s/m in the Keumkwang district, and 2.515×10^-4㎥/s/m in the Gosam district. 6. Operational losses amounted to about 31 times as much as infiltration losses in the Keumkwang district, and about 5times in the Gosam district. 7. Watergrass densities and Manning’s roughness coefficients of Keumkwang and Gosam districts showed a close relationship between them.