A regulated solution to stabilize the river bed of confluence section when transferring flood watershed. Case study for Khe Tri - Ngan Truoi confluence

Abstract

    Ngan Truoi reservoir has been built on Ngan Truoi river but transferring flood to Khe Tri basin before returning to Ngan Truoi river, Khe Tri bridge at the end of Tri river. The problem of stabilizing the Khe Tri's channel when undertaking the task of passing flood flow up to 25 times the natural flow especially in the confluence section is very necessary but complicated. In this study, we use the experimental method on the physical model. Option 1 of the experiment according to the design scheme and option 2 is proposed, including: dredging length the Khetri's river bed is 1220m from Khetri bridge; channelization route consists of 2 curved river with radius of 190m and 160m and 2 straight transitional river with length L = (2.6 ÷ 2.8)B, B=75.6m; Khetri bridge piers are rotated at a 30 degree angle. The comparison results show that the solutions are given in Option 2 reduce the upstream water level from 0.28 ÷ 0.45m, the discharge capacity increases by 13.3%, at the flow bridge area evenly distributed and has no backwater flow, the local loss at the abutment is less than 1.4m. Proposed solutions are applied in practice,