Electronic automation of the weir gates on the River Thames

The Thames Water Authority recently commissioned a feasibility and design study to investigate the possibility of electronically automating the operation of the weirs along the Thames. The results of this study are incorporated in this paper and show that it should be possible to maintain the water level of each reach, measured with precision level sensors mounted above each weir, to within the order of ± 10 mm of a preset level at all times, regardless of water inflow rates, by the use of a distributed computer-based monitoring and control system. The design of this system relies on the use of an equivalent lumped rectangular cross-section model of a reach. The proposed strategy has been illustrated using data for the reach upstream of Caversham Weir and for the eight motorized weir gates at Caversham, Reading. The design has been verified using computer simulations which demonstrate that the system should be sufficiently robust to handle the expected variation of plant parameters. The system will be operated by a lock-keeper during daylight working hours, but will otherwise be unmanned. Accordingly, detailed consideration must be given to the practical implementation of the system so that it will provide the required degree of reliability and will degrade gracefully and fail safe. The paper discusses how these requirements may be achieved.