Model simulations of tidal changes in a coastal lagoon, the Ria de Aveiro (Portugal)

Araújo, I.B.; Dias, João Miguel; Pugh, David

doi:10.1016/j.csr.2008.02.001

Cited by 57 publications

(37 citation statements)

References 14 publications

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“…The results of ebb and flood currents obtained in the previous section corroborate the increase of the ebb dominance in the lagoon central area along the time, as was referred by Araú jo et al (2008). The enhancement of ebb dominance with the increase in the intertidal area is consistent with theoretical (Friedrichs and Aubrey, 1988;Fortunato and Oliveira, 2005) and numerical (Fortunato et al, 1999) evidence.…”

Section: Tidal Asymmetrysupporting

confidence: 79%

“…According to the model results, an increase of the lagoon total area and volume leads to a decrease in the amplitude and an increase in the phase of the major tidal constituent, M 2 , along the Ria de Aveiro, in agreement with the sensibility analysis results performed by Araú jo et al (2008). For the M 4 constituent both amplitude and phase increase.…”

Section: Tidal Asymmetrysupporting

confidence: 75%

“…In this particular case, the correct reproduction of overtides is further hampered by the changes in bathymetry over the years, which significantly affect tidal propagation. For M 2 , an average increase of 0.245 m in amplitude and an average decrease of 17.41 in phase were observed over 16 years (Araú jo et al, 2008). Since there is a discrepancy of about 16 years between the bathymetric and the tidal data used herein, similar discrepancies should be expected between the tidal data and the model results.…”

Section: Hydrodynamic Model Calibrationmentioning

confidence: 54%

“…Inspite of the importance of evaluating tidal changes induced by geomorphologic modifications, only one previous work focusing on Ria de Aveiro tidal changes was found (Araú jo et al, 2008) and only a few were found about its tidal asymmetry (Dias, 2001;Lopes et al, 2006;Oliveira et al, 2006a;Araú jo et al, 2008). However the influence of local geomorphologic modifications, namely the study of flooding scenarios in this lagoon was never investigated.…”

Section: Introductionmentioning

confidence: 99%

“…The results from Oliveira et al (2006a) confirm this pattern, showing differences between ebb and flood durations revealing that the system shifts from mildly ebb dominant at the mouth to strongly flood dominance in the upper reaches of the lagoon. Araú jo et al (2008) reported that during 1987/1988, the majority of the lagoon was flood-dominant, and that since then the central section of the lagoon has become ebb-dominant, whilst the northern and southern sections remain flood-dominant. All these studies show that the ratio between the amplitudes of the M 4 and the M 2 , regarded as a measure of tidal asymmetry, is very small near the lagoon mouth increasing along the channels.…”

Section: Introductionmentioning

confidence: 99%

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Tidal changes in estuarine systems induced by local geomorphologic modifications

Picado

Dias

Fortunato

2010

Continental Shelf Research

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a b s t r a c tAlthough rising global sea levels will affect the estuarine flooded areas over the coming decades, the local and regional-scale processes will also induce important changes in these coastal systems. The main aim of this work is to investigate possible tidal changes in estuarine systems induced by local geomorphologic modifications, analysing the particular case of Ria de Aveiro which is in risk of inundation. Located in the Portuguese west coast, this tidally driven lagoon has a large area of mostly abandoned salt pans, which are in progressive degradation caused by the lack of maintenance and by the strong currents which erode their protective walls.To explore possible tidal changes the hydrodynamic model ELCIRC was applied to Ria de Aveiro to simulate and analyse the impact in the lagoon hydrodynamics of this degradation which results in the enlargement of the lagoon flooded area. A high-resolution grid (grid spacing of the order of 1 m) was developed in order to represent the narrow channels adjacent to the salt pans. The hydrodynamic model was then successfully calibrated and assessed for skill for the Aveiro lagoon through comparison between measurements and model results and quantification of the numerical accuracy. The model was subsequently used to investigate the effect of the flooded lagoon area enlargement on tidal propagation in Ria de Aveiro. Simulations were performed for three geomorphologic configurations, representing the reference or present situation and two flooded scenarios. Results were compared through the analysis of tidal currents, tidal asymmetry and tidal prism.The increase of the lagoon flooded area results in an intensification of the tidal currents, tidal prism and tidal asymmetry. Results also indicate that the tidal prism further increases when the flooding depth increases. Otherwise, changes in tidal currents and in tidal asymmetry pattern are negligible with the increase of the flooded area depth.These results indicate that modifications of the flooded area of estuarine systems will result in tidal changes, with an intensification of the actual tidal patterns induced by the enlargement of inundation areas.

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Section: Tidal Asymmetrysupporting

confidence: 79%

Section: Tidal Asymmetrysupporting

confidence: 75%

Section: Hydrodynamic Model Calibrationmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tidal changes in estuarine systems induced by local geomorphologic modifications

Picado

Dias

Fortunato

2010

Continental Shelf Research

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Global secular changes in different tidal high water, low water and range levels

2015

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Tides exert a major control on the coastal zone by influencing high sea levels and coastal flooding, navigation, sediment dynamics, and ecology. Therefore, any changes to tides have wide ranging and important implications. In this paper, we uniquely assess secular changes in 15 regularly used tidal levels (five high water, five low water and five tidal ranges), which have direct practical applications. Using sea level data from 220 tide gauge sites, we found changes have occured in all analyzed tidal levels in many parts of the world. For the tidal levels assessed, between 36% and 63% of sites had trends significantly different (at 95% confidence level) from zero. At certain locations, the magnitude of the trends in tidal levels were similar to trends in mean sea level over the last century, with observed changes in tidal range and high water levels of over 5 mm yr −1 and 2 mm yr −1 , respectively. More positive than negative trends were observed in tidal ranges and high water levels, and vice versa for low water levels. However we found no significant correlation between trends in mean sea level (MSL) and any tidal levels. Spatially coherent trends were observed in some regions, including the north-east Pacific, German Bight and Australasia, and we also found that differences in trends occur between different tidal levels. This implies that analyzing different tidal levels is important. Because changes in the tide are widespread and of similar magnitude to MSL rise at a number sites, changes in tides should be considered in coastal risk assessments.

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Long-term monitoring of a mercury contaminated estuary (Ria de Aveiro, Portugal): the effect of weather events and management in mercury transport

et al. 2012

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ABSTRACT:The main aim of this research was to assess the mercury transport from an estuarine basin with a background of anthropogenic contamination during a spring tidal cycle (year 2009) and compare it with two previous tidal cycles (years 1994 and 1999), as part of a long-term monitoring program. Results showed that effective mercury transport occurs both in the dissolved and particulate fractions (0.18 and 0.20 kg per tidal cycle, respectively), and despite an overall decrease in environmental contamination, results more than double previous findings on particulate transport in the system. These findings result essentially from changes in the tidal prism (net export of 2 million m 3 of water), given that both dissolved and particulate concentrations did not increase over time. Hydrodynamic simulations were performed to evaluate the effect of physical disturbance (dredging) and weather events (increased freshwater flow) in these processes, and results suggest the increased freshwater flow into the system as the main forcing function for the mercury transport increment. These results highlight the importance of long-term monitoring programs, since despite an overall improvement in local contamination levels, the enhancement of transport processes through hydrological changes increases environmental pressure away from the contamination source.

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Model simulations of tidal changes in a coastal lagoon, the Ria de Aveiro (Portugal)

Cited by 57 publications

References 14 publications

Tidal changes in estuarine systems induced by local geomorphologic modifications

Tidal changes in estuarine systems induced by local geomorphologic modifications

Global secular changes in different tidal high water, low water and range levels

Long-term monitoring of a mercury contaminated estuary (Ria de Aveiro, Portugal): the effect of weather events and management in mercury transport

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