Water Productivity in Tank Cascade Systems: A Case Study in Mahakanumulla Cascade, Sri Lanka

This study was conducted to assess the agricultural water productivity and its determinants in the Mahakanumulla tank cascade system located in the dry zone of Sri Lanka. The data collection for the study was carried out in the form of a survey, where 250 farmer households representing 17 tanks within the cascade were surveyed. The productivity assessment was conducted for the upstream and the downstream of the cascade separately. A regression model was used to identify the determinants of the agricultural water productivity in the Mahakanumulla cascade. The average agricultural water productivity in the upstream was 1.48kg/m³ and in the downstream it was 1.62 48kg/m³. The extent of command area and climate-related crop losses were the critical determinants of the agricultural water productivity both upstream and downstream. In the upstream, the tank capacity was a determinant of the field water productivity and, in the downstream, degree of wildlife damage remained significant in determining water productivity.