Papers by Adrián Pedrozo-Acuña
Coastal Engineering …, 2012
The Yucatan coastline has been experiencing beach erosion during the past few decades, reaching c... more The Yucatan coastline has been experiencing beach erosion during the past few decades, reaching critical levels at some locations such as in Chelem beach located near the Progreso Pier. Despite this problem, only few studies have been devoted to investigate the role of coastal structures on explaining the high erosion rates. Therefore, the aim of this work is to evaluate the effects of the 6-km long Progreso Pier on the nearshore wave transformation and alongshore sediment transport in the study area. Field surveys were conducted in a monthly basis to measure the changes in the beach profiles. Furthermore, wave conditions were determined with an ADCP installed at 8 m water depth. Observations confirmed the high erosion trends(1m/year) that have produced coastal infrastructure damage and property loss along 10 km of coast. The wave measurements were employed as forcing on a third generation wave transformation model (MIKE 21 SW). Firstly, the numerical model is implemented in the study area for two different scenarios, with and without the Progreso Pier structure, in order to estimate the nearshore wave conditions. Subsequently, wave conditions predicted at 5 m water depth were employed for the estimation of longshore sediment transport in the study area. The modeling results showed that the pier acts as a large scale wave-sheltering structure that induces important longshore sediment transport gradients during mean wave conditions coming from the NE. On the other hand, during winter storms, when the dominant direction of the waves is from the NNW, the structure does not seem to play an important role on wave transformation into the study area. As a result, the Progreso Pier enhances beach erosion in the Chelem area by inducing longshore sediment transport gradients during mean wave climate and decreasing the capacity of waves to recover the summer beach profile.
Journal of Coastal Research, Apr 1, 2013
This paper presents an experimental investigation into the morphological response of beaches with... more This paper presents an experimental investigation into the morphological response of beaches with different permeability under the action of plunging wave breaking. Experimental results performed under the same wave conditions, allowed the association of beach evolution to its permeability. Firstly a beach profile which presented the generation of a clear berm at the top of the profile and a beach step below the SWL (high permeability) was illustrated. Secondly, an erosive condition of beach profile was characterised (low permeability). The morphological responses of both beaches were differentiated in terms of the porosity of the beach, which highlight its role in the resulting spatio-temporal nature of the momentum balance under plunging wave breaking. Additionally, BIV derived velocities were utilised as a tool for the investigation of hydraulic regimes responsible of generating different beach responses and sediment sorting in the laboratory. Through Euler’s equation the total acceleration was deconstructed, allowing a careful assessment of the contribution of each the acceleration terms to the resulting momentum balance. Notably, the contribution of the local acceleration term is insignificant all along the beach profile, while the role of advective terms cannot be overlooked.
Journal of Flood Risk Management
This investigation evaluates the effects of hydrological uncertainty in the results of flood exte... more This investigation evaluates the effects of hydrological uncertainty in the results of flood extent estimates during the incidence of a tropical storm. For this, the methodology is comprised of field measurements, elevation data, a distributed hydrological model and a standard 2D numerical model. Uncertainty is considered in the distributed hydrological model, through the estimation of possible hydrographs from precipitation data registered during the incidence of an extreme event. The characterisation of the runoff by multiple possibilities, opens the door to a probabilistic estimation of flood maps, enabling the consideration of hydrological uncertainties and their propagation to an estimated flood extension. It is shown that during the incidence of the tropical storm Arlene, the estimated flooded area is similar to what was registered by satellite imagery. Although the methodology does not consider all the uncertainties that may be involved in the determination of a flooded area, it is reflected that it favours the preventive action in the generation of flood management strategies. The selected approach is a first iteration in the production of a fully quantified approach to the analysis of flood risk; especially where there are doubts about how the catchment responds to a given extreme precipitation event.
Nat. Hazards Earth Syst. Sci., 12, 3765-3773, doi:10.5194/nhess-12-3765-2012, 2012. , 2012
Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon are investigated by ... more Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon are investigated by means of a phase-resolving non-hydrostatic wave model (SWASH). This model solves the nonlinear shallow water equations including non-hydrostatic pressure. The one-dimensional version of the model is implemented in order to investigate wave transformation in fringing reefs. Firstly, the numerical model is validated with (i) laboratory experiments conducted on a physical model (Demirbilek et al., 2007)and (ii) field observations (Coronado et al., 2007). Numerical results show good agreement with both experimental and field data. The comparison against the physical model results, for energetic wave conditions, indicates that high- and low-frequency wave transformation is well reproduced. Moreover, extreme water-level conditions measured during the passage of Hurricane Ivan in Puerto Morelos are also estimated by the numerical tool. Subsequently, the model is implemented at different along-reef locations in Puerto Morelos. Extreme water levels, wave-induced setup, and infragravity wave energy are estimated inside the reef lagoon for different storm wave conditions (Hs >2 m). The numerical results revealed a strong correlation between the offshore sea-swell wave energy and the setup. In contrast, infragravity waves are shown to be the result of a more complex pattern which heavily relies on the reef geometry. Indeed, the southern end of the reef lagoon provides evidence of resonance excitation, suggesting that the reef barrier may act as either a natural flood protection morphological feature, or as an inundation hazard enhancer depending on the incident wave conditions.
This report claims that the two main consequences that climate change has on the coastal environm... more This report claims that the two main consequences that climate change has on the coastal environment in the world, are the increase in mean sea level and changes in wave climate (increases in frequency and intensity of storms). The State of Campeche is a strategic area for Mexico with great economic (e.g. oil zone) and ecological (e.g. 3 species of endangered sea turtles extinction spawn in its coasts) importance. Campeche is already suffering the effects of rising sea levels and the presence of more severe storm surges are ahead. Despite the magnitude of damage and economic costs that are associated with these, there are no reported studies to quantify the estimated costs for the coast of Campeche. In addition, the estimated costs do not consider changes caused by salinization of aquifers and unproductive agricultural areas, making it necessary to consider its impact on food security of the State's population. As a consequence, the Bank commissioned a study on the level of awareness of the problem for current and future vulnerability in the state, in terms of climate change predictions, and the identification of sectors sensitive to rising sea levels within the state.
This investigation presents an integrated study for the identification of coastal and fluvial for... more This investigation presents an integrated study for the identification of coastal and fluvial forcing, in the generation of flood events in the lower area of the Tonala River. The methodology is designed to reduce some of the uncertainties in the results, and is comprised by high-quality field measurements, a 2D numerical model and LiDAR data. Under typical conditions results show good agreement between numerical and measured data. Investigation of mesh resolution effects and roughness parameterisation along the floodplain demonstrate the grid independence of the results, and enabled the selection of a realistic roughness value for the floodplain. Results imply a sensitivity of the region to the combined river and coastal forcing. This study demonstrates that a good description of the terrain elevation, acquisition of high-quality bathymetric data and proper calibration of the roughness parameters, provide the adequate set-up for the identification of vulnerable areas to flood events generated by river discharges and storm surges. The combined scenarios of high discharges and storm surges showed a delicate balance between river and coastal fluxes within this system. The approach could be useful for both, the generation of flood management strategies and the understanding of the role of driving physical processes.
This study presents an investigation into the spatial and temporal evolution of the velocity fiel... more This study presents an investigation into the spatial and temporal evolution of the velocity field induced by plunging waves using the bubble image velocimetry (BIV) technique. The BIV velocity estimates are validated with both direct single-point measurements and a well-validated VOF-type numerical model. Firstly, BIV-derived time series of horizontal velocities are compared with single-point measurements, showing good agreement at two cross-shore locations on the impermeable slope in the swash and surf zones. The comparison includes a discussion on the uncertainty associated with both data sets. In order to evaluate the transient two-dimensional description of the flow field, a high-resolution VOF-type numerical model based on the Reynolds-averaged Navier–Stokes equations is used. A reliable estimation of the numerically derived surf zone velocity is established. In the swash zone, however, an overprediction of the offshore flow is identified, which may be ascribed to the single-phase nature of the numerical description, suggesting the importance of the dynamics of the air/water mixture for accurate modelling of this breaker type. The non-intrusive BIV technique was shown to be a good complementary tool to the numerical model in the estimation of velocity field induced by plunging waves in the laboratory. It is shown that the BIV technique is more suitable when the nature of the velocity field under the presence of an aerated flow is sought. This is relevant for hydrodynamic studies of plunging breakers when, due to air entrainment, the use of other measurement techniques or single-phase formulations in numerical models may provide uncertain results.
This paper presents a review on the usefulness of nonlinear wave propagation models in coastal wa... more This paper presents a review on the usefulness of nonlinear wave propagation models in coastal waters. More specifically, on the use of high resolution spatiotemporal resolution models, such as those based on the Reynolds Averaged Navier-Stokes (RANS) Equations. With this type of models it is possible to carry out detailed studies of the processes before and after wave breaking occurs. In order to demonstrate its potential, some examples of their application are carefully selected showing the level of detail achieved in the description of the flow with this approach. Their diagnostic role to dissect each of the variables involved in the wave breaking process (e.g. velocity, turbulence, pressure gradients), is highlighted. The results presented here confirm that these models are also an excellent tool for studying processes related to wave breaking and wave transformation in the swash zone. It is anticipated that in the years to come, the combination of this type of tool with field or laboratory data will have an important role in coastal engineering development.
This investigation presents laboratory observations on the spatio-temporal evolution of pressure ... more This investigation presents laboratory observations on the spatio-temporal evolution of pressure fields and gradients induced by plunging waves propagating across the nearshore zone. Experiments were carried out to obtain detailed measurements of pressure time-curves and fluid velocities across the shoaling, breaking and swash zones. Pressure envelopes showed a consistent shape in all tests, with minimum values in the swash zone and maximum values at the impinge points. In particular, the nature of the pressure gradient at different locations (shoaling, breaking and swash zones) across the impermeable bed is investigated, revealing maximum values at the impact points. The relationship of the pressure gradient to horizontal velocity and local acceleration is also examined. This investigation enabled the elucidation of an apparent contradiction identified in recent works regarding the relationship between local acceleration and pressure gradient within the surf and swash zones. Consistent with findings of prior studies, results in the shoaling and breaking zone indicated that local fluid accelerations can be used to account for the contribution of pressure gradients. In contrast, the validity of this assumption is not established within the swash zone. In this region, minimum pressure gradients are identified and local acceleration is negative (offshore) for almost the whole swash cycle, consistent with previous field observations. Thus, for plunging breakers driven-swash, results point toward the significance of the advective terms acting against local acceleration. Furthermore, measurements of the velocity field by a validated Bubble Image Velocimetry (BIV) technique provide a qualitative description of the highly aerated flow, revealing that maximum values of vertical velocities are associated with the wave-impact from a plunging breaker impinging on the bed. These results indicate the need for a detailed characterisation of the pressure gradient under different types of wave breaking.
This investigation comprises the hydraulic characterisation of a river located in the Mexican Sta... more This investigation comprises the hydraulic characterisation of a river located in the Mexican State of Tabasco, including the performance of its flood plain under the action of an extreme river discharge. This is done through the combination of a high-quality validation dataset, remote sensing information, and a standard 2D numerical model. The dataset was collected during an intensive field campaign that took place in August 2009. In particular, in situ measurements of river discharge, bathymetry, water level, and velocities through a whole tidal cycle are employed along with multi-spectral satellite imagery. The purpose of this study is twofold. Firstly, the integrated approach comprising the combination of a 2D hydrodynamic model, high-quality in situ measurements and satellite imagery reduce the uncertainty in the model parameterisation and results. Secondly, it is shown that freely available sources of information, such as the Shuttle Radar Topographic Mission (SRTM) data can be processed and utilized in 2D hydraulic models. This is particularly important in countries where high-resolution elevation data is not yet available. It is demonstrated that the selected approach is useful when the study of possible consequences in a flood plain induced by an extreme flood discharge are sought.
This paper presents observations of pressure impulses from wave impacts of breaking waves on stee... more This paper presents observations of pressure impulses from wave impacts of breaking waves on steep coarse-grained beaches. It builds upon recent investigations on gravel beaches which suggest the wave impact of a plunging breaker is an important process that shapes the morphology of these beaches and that is not taken into account under many modelling frameworks (Pedrozo-Acuña, A., Simmonds, D.J., Chadwick, A.J. and Silva, R., 2007. A numerical–empirical approach for evaluating morphodynamic processes on mixed and gravel beaches. Mar. Geol., 241(1–2): 1–18). Full scale laboratory measurements of induced pressures by plunging breakers acting on gravel beaches are reported showing that these are more significant than those reported for sandy beaches under the forcing of similar wave conditions. Additionally, four different types of pressure-curves are identified and classified in terms of the type of forcing behind its generation. It is shown that measured impact pressures within the gravel beach are a consequence of plunging breakers propagating over the beach profile, with maximum pressure values being up to 4.5 times the quasi-hydrostatic induced pressure for a given wave height. It is demonstrated that the largest measured impacts are not only related to larger values of wave height and vertical displacement of the free surface but also to the wave steepness of the incident wave. Results suggest that between two plunging breakers of the same height, the steeper will produce a stronger wave impact. The plunging of breakers onto a gravel beachface and the ensuing pressure gradients are suggested as a key mechanism for understanding sediment transport and the resulting morphology of gravel beaches.
Pedrozo-Acuña et al. [Pedrozo-Acuña, A., Simmonds, D.J., Otta, A.K. and Chadwick, A.J., 2006. On ... more Pedrozo-Acuña et al. [Pedrozo-Acuña, A., Simmonds, D.J., Otta, A.K. and Chadwick, A.J., 2006. On the cross-shore profile change of gravel beaches. Coastal Engineering, 53(4): 335–347] presented a numerical–empirical investigation of the processes that control sediment transport in the swash zone on steep gravel beaches. This was based on a sensitivity analysis of a sediment transport/profile model driven by a highly non-linear Boussinesq model [Lynett, P., J., Wu, T.-R. and Liu, L.-F., P., 2002. Modelling wave run-up with depth-integrated equations. Coastal Engineering, 46: 89–107] which was compared to near full-scale measurements performed in the GWK flume in Hanover. In this paper we have extended our analysis to compare these earlier results with those relating to a mixed sediment (gravel and sand) beach. The parametric sensitivity analysis also incorporates a discussion of the effects of acceleration about which there is much debate. The sensitivity analysis suggests that fluid acceleration can contribute to the onshore movement of sediment that causes steepening of initially flat beach faces composed of coarse sediment. However acceleration alone cannot be the cause of the observed berm growth during the GWK tests. Instead, a complex balance of processes is responsible for the profile evolution of coarse-grained beaches with no single dominant process.
This paper investigates cross-shore profile changes of gravel beaches, with particular regard to ... more This paper investigates cross-shore profile changes of gravel beaches, with particular regard to discussing the tendency for onshore transport and profile steepening in the swash zone. The discussion includes observed morphological changes on a gravel beach from experimental investigations at the Large Wave Flume (GWK) in Hanover, Germany. During the tests all the profile changes occurred in the swash zone, resulting in erosion below the still water line (SWL) and formation of a berm above the SWL. We investigate the profile evolution evaluating the transport rates from a bed load sediment transport formulation coupled with velocities calculated from a set of Boussinesq equations that have been validated for its use in the surf and swash zones [Lynett, P.J., Wu, T.-R., and Liu, L.-F., P., 2002. Modelling wave runup with depth-integrated equations. Coastal Engineering, 46, 89–107; Otta, A.K., and Pedrozo-Acuña, A., 2004. Swash boundary and cross-shore variation of horizontal velocity on a slope. In: J.M. Smith (Editor), Proceedings 29th International Conference on Coastal Engineering. World Scientific, Lisbon, Portugal, pp. 1616–1628]. We discuss the influence of bottom friction on the predicted profiles, using reported friction factors from experimental studies. It is shown that the use of a different friction factor within a realistic range in each phase of the swash (uprush and backwash) improves prediction of the beach profiles, although quantitative agreement between the measured and computed profile evolutions is not satisfactory. Furthermore, if the friction factor and the transport efficiency (C) of the sediment transport formulation are kept the same in the uprush and backwash, accurate representation of profile evolution is not possible. Indeed, the features of the predicted profiles are reversed. However, when the C parameter is set larger during the uprush than during the backwash, the predicted profiles are closer to the observations. Differences between the predicted profiles from setting non-identical C-values and friction factors for the swash phase, are believed to be linked to both the infiltration effects on the flow above the beachface and the more accelerated flow in the uprush.
This paper provides information on the experimental set-up, data collection methods and results t... more This paper provides information on the experimental set-up, data collection methods and results to date for the project “Large scale modelling of coarse grained beaches”, undertaken at the Large Wave Channel (GWK) of FZK in Hannover by an international group of researchers in Spring 2002. The main objective of the experiments was to provide full scale measurements of cross-shore processes on gravel and mixed beaches for the verification and further development of cross-shore numerical models of gravel and mixed sediment beaches. Identical random and regular wave tests were undertaken for a gravel beach and a mixed sand/gravel beach set up in the flume. Measurements included profile development, water surface elevation along the flume, internal pressures in the swash zone, piezometric head levels within the beach, run-up, flow velocities in the surf-zone and sediment size distributions.The purpose of the paper is to present to the scientific community the experimental procedure, a summary of the data collected, some initial results, as well as a brief outline of the on-going research being carried out with the data by different research groups. The experimental data is available to all the scientific community following submission of a statement of objectives, specification of data requirements and an agreement to abide with the GWK and EU protocols.
Artículos by Adrián Pedrozo-Acuña
This investigation evaluates the effects of hydrological uncertainty in the results of flood exte... more This investigation evaluates the effects of hydrological uncertainty in the results of flood extent estimates during the incidence of a tropical storm. For this, the methodology is comprised of field measurements, elevation data, a distributed hydrological model and a standard two-dimensional numerical model. Uncertainty is considered in the distributed hydrological model through the estimation of possible hydrographs from precipitation data registered during the incidence of an extreme event. The characterisation of the runoff by multiple possibilities opens the door to a probabilistic estimation of flood maps, enabling the consideration of hydrological uncertainties and their propagation to an estimated flood extension. It is shown that during the incidence of the tropical storm Arlene, the estimated flooded area is similar to what was registered by satellite imagery. Although the methodology does not consider all the uncertainties that may be involved in the determination of a flooded area, it is reflected that it favours the preventive action in the generation of flood management strategies. The selected approach is a first iteration in the production of a fully quantified approach to the analysis of flood risk, especially where there are doubts about how the catchment responds to a given extreme precipitation event.
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Papers by Adrián Pedrozo-Acuña
Artículos by Adrián Pedrozo-Acuña