Multidimensional analysis of nexus technologies II: dynamics of traditional and modern irrigation systems

From a technological perspective, irrigation is a dynamic field undergoing a shift from a horizontal expansion of the area equipped for irrigation (or “total irrigation market”) to a vertical transition of the technology mix in search of higher intensification and efficiency (more crop per drop). As a result, the “irrigation market” is currently experiencing a gradual transformation process from traditional flood irrigation towards more efficient pressurised irrigation technologies (sprinkler and drip). The results of this study suggest that these substitution dynamics will continue in the future, favouring the most recent and efficient technology, i.e. drip irrigation. A logistic projection of historical growth predicts drip to reach the highest growth rate among all technologies by 2035, and start a fast expansion over not only flood irrigated areas, but also sprinkler irrigated areas. The cost and size dynamics of irrigation projects are less clear given the extremely high context dependency and variability of some critical factors determining irrigation project costs, as well as the important differences across regions. Economies of scale also vary across regions, and are estimated to be higher for rehabilitation and modernization projects than for new development projects, with scale factors of 0.6 and 0.97 respectively. Regarding the learning effects, the limitations in data quality and completeness do not allow to derive clear quantitative and technology specific estimates of learning trends. Nevertheless, some positive learning is detected in rehabilitation projects since 1990 and certain cost reductions at the application technology level are reported by consulted irrigation technology experts. Focusing on the regions of interest for ISWEL case studies, South Asia may see a rapid expansion of drip irrigation through both private modernization initiatives at the small-medium scale and public large scale rehabilitation-modernization interventions on historica