Assessment of Irrigation Canal Seepage Losses and Lining Efficiency in North West Nigeria

This study provides a rigorous assessment of seepage losses from unlined and lined irrigation canals in North West Nigeria, quantifying water losses and evaluating the hydraulic efficiency of different canal lining materials under field conditions. Canal seepage is a major source of water loss in Nigerian irrigation schemes, with estimates suggesting that up to 40 percent of water diverted into main canals never reaches farm fields. In North West Nigeria where water scarcity limits irrigation expansion, reducing canal seepage losses could free significant water resources for extending irrigated area. This study measures seepage rates using inflow-outflow method and ponding tests on 18 canal reaches representing unlined earthen, concrete-lined, polyethylene-lined, and compacted clay-lined configurations in Kebbi, Sokoto, and Zamfara State irrigation schemes. Seepage rates at different soil moisture conditions are measured over 30-day measurement periods. Canal hydraulic efficiency is computed from seepage measurements. Cost-benefit analysis compares lining options. Findings reveal that unlined earthen canal seepage rates average 1.8 litres per second per 100 metres, reducing to 0.12 for concrete lining, 0.28 for polyethylene lining, and 0.65 for compacted clay lining. Canal hydraulic efficiency improves from 55 percent for unlined canals to 94 percent for concrete-lined canals. Economic analysis shows that concrete lining is cost-effective for main canals but not secondary distribution channels. The study recommends polyethylene lining as a cost-effective intermediate solution for secondary canals.

Keywords: canal seepage, irrigation efficiency, canal lining, North West Nigeria, water loss.