Development and sensitivity analysis of hydrodynamic model for a tidal channel in an urban area. Case study: Guayaquil city

Eng. Julio Torres, BSc

Master's thesis

Abstract:

Natural hazards, primarily floods, affect the worldwide population’s daily life, and their impacts have been well studied from different edges. Estuaries and coastal areas are of vital importance in the lives of human beings, especially those who live in their vicinity. However, these ecosystems have been degraded yearly with an accelerated loss. In delta cities such as Guayaquil, tidal channels are significant natural assets that help society in many ways. Hence, hydrodynamic models must be developed and used to comprehend the intricate interplay between natural and artificial forces and create efficient management methods. In this context, the current study focuses on the hydrodynamic modelling of branch A of the Estero Salado in Guayaquil, Ecuador. Moreover, A set of 18 scenarios were simulated in order to get a clear picture of how the hydrodynamic model of channel A in the Salado estuary would react to changes in boundary conditions, hydraulic roughness, and time step. This sensitivity analysis aims to show how sensitive the model’s outputs are to changes in an input variable, analyzing two parameters, the maximum water surface elevation and the flood area. In addition, the combination of the worst boundary condition was found. The results revealed that the system could collapse when the channel faces high tide levels and the peak of the hydrograph. Additionally, the boundary conditions greatly impacted the model results, having a difference of more than 25% in reservoir levels and more than 80% in the flood area (between a 2-year event and another 100-year event). However, this significant difference was not seen when the hydraulic roughness was analyzed, having only differences even less than 1%. Finally, the computation time analysis showed clear signs that 1 minute is sufficient to maintain stability in the model and obtain optimal results (without error carryover) in a relatively low computation time. The study concludes that the canal will overflow in extreme precipitation that coincides with high tide, affecting the surrounding houses. It also makes clear ideas for improvement and future analysis that allow deepening the study of the estuarine ecosystem.

Keywords

Hydrodynamic, Numerical model, HEC-RAS, Sensitivity analysis

Language used: English

Date on which the thesis was submitted / produced: 4. 4. 2023

Thesis defence

• Date of defence: 16. 5. 2023
• Supervisor: Ing. Luděk Bureš, Ph.D.
• Reader: Petr Máca, Ph.D.

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Master programme:
Environmental Modelling