Optimized Water Delivery to Farmers in Maduru-Oya, Sri Lanka, Using Irrigation Demands Communicated through SMS Messaging

Traditional delivery of water to farmers in the Maduru Oya river basin in Sri Lanka is based on seasonal reservoir releases into diversion canals and distribution canals that gravity-feed the farms. Usually water delivery schedules for the main canal are decided by the Mahaweli Authority. These schedules do not give incentives for the farmers to save water, or make improvements to delivery system efficiency. This paper describes a computer based water-quota system that relies on SMS (text) messages sent by the farmers requesting water, and a computer based water delivery system that calculates hydraulic structure gate openings for the water managers. As the first step, an unsteady flow model is developed based on the solution of the St Venants equations to analyze the hydraulics in the canal. Hydraulic transients due to inflow and outflow gate operations are investigated using this model. The results are used to develop a simple operational model for the canal system that can calculate the gate openings necessary for quota based water deliveries. The project makes use of recent advances in information technology (IT) and cheapening of computational capabilities to assist water management and farm water delivery.