A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management, School of Engineering and Technology

Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 2011

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 addition, the study was carried out to assess the differences in water losses through the lined and unlined 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 (KAl) 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. The daily seepage rate was 264.48 m3 / km and 54.6 m3/ km from unlined and concrete lined watercourses. The concrete lining saved 77 % of seepage water losses or daily (209.88 m3 /day/km length of canal). 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 and benefit cost ratio (B/C) was of 4.13, 9.97 and 9.83 from wheat, grapes and tomatoes individually. Moreover, the analysis also assessed increments in cropping intensity after watercourse improvement by 16.69 %, 7 .83 % and 26.58 % from wheat, grapes and tomatoes respectively.