FLOW AND SEDIMENT MOVEMENT MONITORING IN LARGE SEWERS

The development of more precise computer models for the simulation of the performance of sewerage systems and for management in real-time ne cessitates the acquisition of more precise data. Existing portable sys tems for the in-situ measurement of velocity in sewers as commonly use d for model development have limited applicability to larger sized sew ers (>1200mm). When considered together with the emerging need to moni tor the behaviour of sediments in sewers, this lack of instrumentation available to observe detailed velocity gradients in the larger sewers , where sedimentation is most likely to occur, is a severe constraint. A programme of research studying sediment movements in the sewers in Dundee has led to the development of ultrasonic systems for the measur ement of three dimensional velocity distributions in large sewers, and sonar systems for the monitoring of bed erosion at points within the sewer network. Data obtained from these systems has contributed to the development of a new cohesive sediment erosion model for sewers.