They are, however, gaining greater acceptance because they provide maximum flexibility for rice irrigation. Growers with recirculating systems have a shorter water holding period, after pesticide applications, than do growers who use conventional systems. Schematic diagram of a recirculating tailwater recovery system. Power for tailwater pumps may be supplied by electric motors, or internal combustion engines where electricity is not available. Pumps are used to lift the tailwater either directly to the field or into a highline ditch.
Water then flows via gravity back through the irrigation system.
To obtain optimal performance from a larger recirculating system, fields should be laser-leveled and the flow of water must be directed to drainage ditches leading to the main drain. The depth of water in each basin is controlled by conventional rice boxes. Farm size has been found to greatly affect per acre cost of recirculating systems. Table 2 presents the advantages and disadvantages of a tailwater recovery or recirculating irrigation system.