Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, Turkey

Approval Date: 2019

Thesis Language: English


Supervisor: Zafer Bozkuş


In this study, flood scenarios of bridge sections of Wami and Düden Rivers are examined with 2D flood modelling. HEC-RAS 2D software is used for the flood simulations. The bridge locations are investigated to protect against hazardous floods expected in the regions. For Wami Bridge, three scenarios are examined; existing case (where only the operated bridge is modelled), design case (where the newly designed bridge is added) and modified design case (where channel modification is introduced with both bridges). For Düden Bridge, existing case (where the historical bridge with insufficient openings) and modified case (where an adjoint bypass channel sharing the flood discharge) are simulated. In the analyzes, instead of 1D modelling, 2D modelling is preferred because of the flat topographic characteristics of the regions, absence of defined riverbed and parallel channels with different slope profiles. For Wami Bridge, using trapezoidal channelization with 15-m width and 2-m depth, the water height at the designed bridge is lowered to 1.45 m and the discharge capacity is increased to 100.74 m3/s while the discharge capacity of the existing bridge is increased from 20.40 m3/s to 100.63 m3/s. For Düden Bridge, using a rectangular by-pass channel, the water height at the historical bridge is lowered to 3.40 m, at which the historical bridge will enable the passage of QDüden = 110.69 m3/s and the bypass channel will carry the rest of the flood, that is, Qbypass = 141.19 m3/s. As a result, the flood control alternatives with hydraulically appropriate solutions were identified for both cases.