Development of a stream wheel to harness the available hydropower in steep irrigation channels to provide pressured irrigation systems to high elevation fields
Moji Banjo, Michael Brown, Vinura Jayewardene, Kyle Ogata, George Olteanu, Iman Warsame
Dr Gerald Muller
This design is a low-cost solution to improve irrigation using water saving systems and a pump to move water to reservoirs higher up, increasing the irrigated area. The wheel-pump system developed could be adapted to provide water or electricity in a range of remote areas lacking electricity connections.
The development and implementation of water-saving irrigation systems is a significant concern in order to meet future water requirements and predicted population rise. At present 20% of the world’s agricultural area is irrigated and produces 40% of the total production. Irrigation uses 70% of global freshwater consumption.
Water saving irrigation systems such as drip and sprinkler irrigation require pressurised flow which means pumps, power supply lines and ongoing expenditure for electricity. In irrigation channels, there is a significant amount of currently unused hydropower from drops structures, and excess hydraulic energy is dissipated. There is currently no technology to combine hydropower and pumps to create pressurised flow for irrigation. This project aims to design a hydro-powered pump system to provide water saving irrigation in these rural areas, where it is challenging to irrigate by traditional means.
A 1.0kW supercritical stream wheel with 1.60m diameter and 0.80m width was developed to power a piston pump to provided 1.1 l/s of water at 80m pressure head to a two-hectare field. Small scale tests were undertaken to determine the required channel blockage, blade shape and extracted power. Larger-scale tests were undertaken at Chilworth outdoor flume, with a 1.60m diameter and 0.4m wide blade, to investigate potential issues when utilising larger volumes of water. These tests allowed the simulation of the integrated system and an accurate prediction of full-scale characteristics.