Impacts of Alternative Water Policy Scenarios on Sustainability of Irrigation Development in Lake Tana Basin, Ethiopia: A Positive Mathematical Programming Approach

Abstract

Although the achievements of irrigation in ensuring food security and improving rural welfare have been impressive, the practice had encountered a number of problems and failures of irrigated agriculture in relation to its high water consumption and other environmental concerns. This study has investigated the impacts of alternative water policy scenarios on sustainability of irrigation developmentby applying a PMP simulation model in two modern irrigation schemes of Lake Tana Basin, Ethiopia. According to the simulation model, implementation of each alternative water policy scenario may result in reduction of total cultivated land in both irrigation schemes. In general, implementation of alternative water policy scenarios may lead to deterioration of the economic (i.e. reduction of private income) and social (i.e. reduction of rural labor demand) roles of irrigated agriculture in the study area, while, at the same time, it will improve the environmental sustainability of irrigated agriculture (a reduction of negative externalities such as consumption of irrigation water and release of agrochemicals such as fertilizers and pesticides).Although measuring the overall impacts of alternative policies requires composite indicators of sustainability, the results of this study suggested that, in general, relatively lower water price levels are conducive to meet the environmental requirements with less economic and social impacts, and will result in a more sustainable irrigation development if they are complementarily applied with restricted water supply levels. Furthermore, the results suggested that water policies should be designed in such a way that they are able to address a specific objective(s) of water resource management. The results of this study can be useful as they will enable policy makers to reflect on the design and implementation of policies that affect the sustainability of irrigated agriculture. The results of this analysis may also be relevant in improving the existing water policy at national level