FLOW CHARACTERSTICS IN COMBINING CHANNELS

Abstract

The flow characteristics of combining channel networks which are practically encountered in drainage, hydropower, irrigation, treatment plants, and river engineering systems have been investigated by various researchers experimentally. This dissertation work besides giving an exhaustive review of the existing knowledge on the problem, it presents a theoretical approach of handling some of the hydraulic problems in combining channel networks. An algorithm is developed with computer coding for the prediction of depth rises just upstream of the junction and back-water effects further upstream in the tributary channels. The depth rises, due to combination of flows, in the tributary channels vary with discharge ratio from the lateral tributary channel even though the trend of variation differs for each channels. The study has shown that the magnitude of depth rise increases in the main tributary channel with an increase of discharge ratio from the lateral tributary channel but the reverse is observed for the later case. Based on the out put of the study, an additional criteria which must be considered while designing combining channel networks is given. It is also remarked that the size of separation zone, junction angle, and the difference in bed level of the tributary channels at the junction affects the magnitude of depth rises. Hence, the study has revealed the need of special treatment for the design of such channel networks due to the complexity of flow pattern created around the junction of combined channels.