Water Availability, Crop Choices and Profitability of Farming: A Case Study of Mahakanumulla Tank Village

Village Tank Cascade Systems (VTCSs) were built in ancient Sri Lanka as self-reliant and climate-resilient agro-ecological systems. This study examined crop choices and profitability of farming under alternative rainfall regimes in a well-functioning tank village system in Mahakanumulla VTCS in Anuradhapura district. A Linear Programming (LP) model was developed to represent farming activities in the tank village for the 2018-19 Maha and 2019 Yala seasons using data gathered from secondary sources and a key informant survey. The baseline equilibrium was calibrated treating farmers as profit maximisers cultivating four types of land (uplands and lowlands in Maha and Yala seasons), two types of labour (hired and family), and twelve-monthly water constraints. The model was simulated under alternative rainfall regimes and technological interventions. The optimal crop mixes, farm profits, and shadow prices of resources associated with the baseline scenarios were compared with those of counterfactual scenarios. The results of the analysis indicated that the success of an intervention is determined by the rainfall regime. The analysis further showed that the introduction of a short-aged rice variety helps more in mitigating drought in a Maha season and the introduction of a traditional rice variety helps more in drought during Yala season. The positive effects of desiltation is quite large when a traditional rice variety is introduced in a Maha drought. Provision of seasonal weather forecasts, which will enable farmers to choose appropriate technological interventions, is recommended.