Name: Maria Fernanda Morales Santillan
Type: MSc dissertation
Publication date: 28/02/2020
Advisor:
Name |
Role |
|---|---|
| Julio Tomás Aquije Chacaltana | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| José Antônio Tosta dos Reis | Internal Examiner * |
| Julio Tomás Aquije Chacaltana | Advisor * |
| Marcos Nicolás Gallo | External Examiner * |
Summary: Commonly, coastal water bodies are subject to anthropic action due to the
various human activities that take place near the coast. Any change in the
coastline or coastal sea bed directly impacts the behavior of the local water
movement. It is extremely important to know the scope of the environmental
impact, whether they are limited to the place of human intervention or if they
spread far from it. In the latter case, it is a priority to know quantitatively the order
of magnitude of the impact caused to the environment in order to evaluate the
mitigation measures to obtain the much-desired sustainable development. It is
well known that the impact on the aquatic environment has the potential to cause
changes in hydrodynamics, which in turn causes changes in sediment transport,
which can change navigation capacity, water quality and coastal flood patterns.
This work investigates changes in hydrodynamics due to the deepening of a
seabed region of a coastal water body. With the purpose of boosting tourism in
the coastal lagoon of Bay of San Quintín Lagoon (SQBL), in 2014 a dredging
project was proposed in the north of the east branch of the Lagoon of the Bay of
San Quintín. This coastal lagoon is a body of hypersaline water formed by two
arms (east and west) and it is located north of Mexico in the Pacific Ocean. The
project intends to change the depth from 0.5 m to 2 m in an area of 116,221 m2
.
In order to understand the impact of deepening on hydrodynamics, this work has
used the computational fluid mechanics technique, in this sense and for the
purposes of this work, Delft3D was used. The model was set up in the study
region and the astronomical tide and the wind were the external forces
considered to force the model. Numerical simulations were performed to assess
the sensitivity of the hydrodynamic model. To assess the influence of the
deepening on hydrodynamics, two scenarios were considered, without and with
a deepening region. Results are presented for the spatial and temporal behavior
of both water level and water velocity. The comparison of numerical results with
those measured in the field showed a good performance, with errors of 4% in
elevation and 12% averaged in currents. The results during the simulation period
showed that in the deepened region there was a maximum reduction in the tide
height during the spring tide, reaching maximum values of 0.47 m while changes
in the tide height during low tide was imperceptible. On average, in the simulated period, there was a decrease of 4 cm in the water level with deepening.
Regarding the water velocity, the greatest variations also occur during the spring
tides. A maximum reduction of 0.14 m/s was found in the deepening region,
representing a decrease in speed of approximately 70% when compared to the
velocity without deepening. Finally, the results suggest that the deepening of the
study area causes a localized impact, generally producing a decrease in the
magnitudes of the flow velocity over the deepened region.
