This study evaluates lined and unlined watercourses through various methods such as inflow – outflow and ponding method. It aims to examine seepage losses rate in both earthen unlined and concrete lined watercourses in the particular area of Dahla Dam irrigation system in Kandahar. The results indicated that seepage losses rate was 0.0 2526 m3/m2/day at 100 m section in secondary sandy loam canal (KA1) by inflow-outflow method. Likewise, the results from tertiary canal (KA4), unlined watercourse (KA3) and lined watercourse (KA2) by ponding method was 0.332 m3/m2/day, 0.212 m3/m2/day and 0.0478 m3/m2/day respectively. Economic analysis was used to compare two alternatives concrete lining cost with water value which was saved by concrete lining. Furthermore, the capital recovery factor addressed annual cost of concrete lined watercourses USD 2991.97 (134638.91 Afghanis).where the upgrading of the watercourse resulted saving water of 68,211 m3/km/year which valued USD 9377.81, 26839.93 and 26427 per year from wheat, grapes and tomatoes respectively. So, annual net benefit was USD 741.15, 5440.8 and 1106.80 per hectare from wheat, grapes and tomatoes correspondently.