Development of a decision support tool: preliminary analysis to improve field data collection in Kathiraveli Village, Sri Lanka

This paper focuses specifically on the development of a water balance model that will support agricultural decision making for the irrigation field and water supply tanks. The study based on an irrigation system within Kathiraveli, an isolated war affected village in north-eastern Sri Lanka. The irrigation system is used to deliver water to approximately 100 farmers. Estimates or measurements of water availability at the start of the cultivation period are able to be combined with estimates of likely future inflows based on previous rainfall to determine optimum crop selection and crop area allocation. The model consists of three modules: a crop water requirement calculator, a water tank balance model, and a model which simulates the storage in the permanent wetland attached to the irrigation tank. Due to limited budgets and timeframes to obtain input data, a careful balance between accuracy, complexity and cost needed to be reached to ensure that the model can be accurate for its intended use. To do this the model was ran initially under baseline conditions. A sensitivity analysis was then performed to assess the importance of major variables; the outcomes of this study was used to prioritise the collection of field data.