Investigation of the effects of uncertainties of inflow hydrograph and dam breach geometry on outflow hydrograph

---

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Civil Engineering, Turkey

Approval Date: 2021

Thesis Language: English

Student: NESLİHAN PINAR GÖDEK

Principal Supervisor (For Co-Supervisor Theses): Ali Melih Yanmaz

Co-Supervisor: Melih Çalamak

Open Archive Collection: AVESIS Open Access Collection

Abstract:

Precise breach outflow hydrograph is crucial for the accurate determination of the flood damage and cost at the downstream region. Precise flood inundation modeling is based on the use of a realistic breach outflow hydrograph as an input. Therefore, comprehensive modeling is essential for an accurate description of breach hydrograph. This study evaluates the effects of dam breach parameters and inflow hydrograph on the peak breach outflow utilizing a probabilistic dam breach model. An experimental model was scaled through Froude similarity, and the deterministic model was developed through HEC-RAS (5.0.7). Dam breach parameters and inflow hydrograph were characterized with probability density functions in accordance with related literature. Probabilistic analyses were conducted using Monte Carlo Simulation through McBreach (5.0.7). Exceedance probability curves and peak flow distribution histograms were obtained for the peak breach outflows, and statistical distributions most widely used in water resources engineering were fitted. The goodness of fit was tested for examination of their suitability. The study showed that the uncertainty of the final breach bottom elevation does not significantly affect the peak breach outflow. The inflow hydrograph characterized with normal Probability Density Function (PDF) covers a broader range of peak breach outflows. The probabilistic peak breach outflow can be characterized with the common extreme type distributions.