Assessing the Sustainability of Drainage System in Irrigated Agricultural Land: A Case Study of Kano River Irrigation Scheme in Nigeria
Bayero, Muhammad Tukur
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Large scale public irrigation schemes in Nigeria are underperforming despite the high investment cost and several institutions managing the projects. In fact, out of about 62 reviewed public irrigation schemes managed by 12 River Basin Development Authorities, some 90% of the area under irrigation is under only three projects and two RBDAs. Nigeria needs irrigated agriculture, like never before, to meet the food and fiber demand of the growing hungry and poor population to achieve zero hunger by 2030. To do so, different kinds of innovative approach and interventions must be employed to succeed in this ambitious target. Hence the study was undertaken. The DRAINFRAME approach was used in problem identification to understand the drainage related problem integrating the water managers and water users, i.e. stakeholders. Field study and semi-structured interviews with stakeholders provided relevant information that informed the direction and in-depth understanding of the problem. Remote Sensing (RS) and Geographic Information System (GIS) techniques were used to estimate the Land Use and Land Cover (LULC) trends and waterlogging areas within the KRIP command area, and the Net Farm Income (NFI) was calculated to evaluate the agricultural benefits. Our findings indicate that the agricultural land drainage in the KRIP command areas is the source of water for unauthorized drainage water reuse, farmers consider it as fertile land for cultivation, and it is highly infested with aquatic weed. From the analysis of LULC trend, it was found out that agricultural land and built-up areas have increased by 43.47 Km2 and 8.19 Km2 between 1988 and 2018 respectively indicating that agricultural development and infrastructure development is taking place. Estimation of the waterlogged regions within LULC classes showed that agricultural lands are most affected and covered 48% of the total waterlogged area. Also, it was found that seepage and leakage of the unlined irrigation canals could be occurring at least 50 meters on both sides of the canals which was estimated to be 29.18% of the total buffered area. Furthermore, NFI of average landholding of 0.46 ha is high enough to encourage paying for more Irrigation Service Fee (ISF) for efficient operation and maintenance that will result in increased agricultural productivity. Based on our findings, agricultural land drainage in KRIP command area is used in the wrong way for good purposes, i.e. cultivation and drainage water reuse. As a consequence, waterlogging situations are dominant especially during the wet season. This will lead to secondary salinity if nothing is done thereby reducing that land fertility. The KRIP, although, poorly performing, was found to provide agricultural benefits. Therefore, irrigated agriculture if adequately managed, will not only be sustainable but also help in meeting the food and fiber demand. The knowledge and recommendations generated in this research is useful for decision-makers, development institutions, water managers and water users.