Abstract
The issue of water losses through irrigation systems has a major impact on surface water supplies and
management. Although a number of national and international organizations have attempted to assess the degree
of losses from the watercourses, the impact of lining on the same command on the water losses had not been
addressed. A study was carried out to assess the differences in water losses through the lined and unlined
watercourses in the particular area of Indus Basin of Pakistan. The selected watercourses were located on the
same distributary; therefore, it was considered that all of these watercourses would be subjected to same hydrogeologic characteristics of soil. It was observed that for the lined watercourses, the irrigation water losses ranged
from 35 to 52 percent and for the unlined these were from 64 to 68 percent. Comparing the average water loss of
43.5 % from lined to the average water loss of 66 % from unlined watercourses, it was concluded that the lining
reduced water loss by 22.5 %. It is emphasized that the studied watercourses were quite old with poor
maintenance conditions. Lining was deteriorated badly with frequent cracks in the walls. The excess leakage of
water through these watercourses was probably due to cracks, eroded mortar and structural failure of the lined
walls. Moreover, the lined watercourses were raised, which accelerated the leakage phenomena. In addition, the
capacity of watercourse was reduced due to silting, resulting in overtopping of flows at many locations.
Consequently, the lined watercourse could not effectively save the water losses and resulted in higher water loss
than the normal.
