Natural Inlet Research Articles

Satellite observations of suspended particulate matter concentration in Lake Gaoyou in the past four decades

Suspended Particulate Matter (SPM) concentration stands as a pivotal determinant of water quality within lake ecosystems. However, comprehension of the enduring dynamics of SPM within lakes is severely hindered due to a shortage of long-term records. Our research has developed a robust remote sensing algorithm to retrieve the SPM concentration in Lake Gaoyou, situated in the lower reaches of the Huai River basin in China. The algorithm demonstrates commendable performance, with an uncertainty of 28.68 %. Leveraging Landsat series sensors imagery, our investigation yields high spatial resolution SPM concentration maps, which first provide a four-decades record of the SPM distribution within Lake Gaoyou. Our findings unveil a significant annual reduction of 1.35 mg L−1 in SPM concentration over the past four decades. This notable decline is probably attributable to a series of ecological initiatives to enhancing the management of the eco-friendly within the basin. Furthermore, our research delineated the influence of environmental factors on the intra-annual SPM dynamics across distinct spatial domains, encompassing the natural inlet region, semi-obstructed inlet region and outlet areas within the lake The SPM concentration in the natural inlet region exhibits a conspicuous correlation with precipitation. Increased precipitation induces runoff within the basin, facilitating the transport of suspended solids and sediment into the lake, consequently augmenting SPM levels. Conversely, the semi-obstructed inlet and outlet areas are predominantly influenced by the wind field, with variations in SPM attributed to sediment resuspension caused by water mixing driven by wind forcing. Our research can be considered an important reference to the evaluation of the management of the lake over long periods.

Numerical Simulation of the Combustion Characteristics in a Flue Gas Internal Recirculation Burner

The combustion characteristics and NOx emissions of a newly designed flue gas internal recirculation low-NOx burner (FIR) were studied. In the study, experimental and numerical simulations of the FIR low-NOx burner were conducted under natural inlet air conditions at three different powers. Results show that the fuel inlet strongly influences the jet effect, thus influencing the flue gas recirculation rate, flame stability, and NOx emissions. With a medium power of 20 kW, the NOx emission of a FIR low-NOx burner is lower than 30 mg/N m3. Higher or lower power will increase the NOx emissions or induce combustion instability. The swirling flow and bluff body structure can effectively improve the combustion stability. Three dominant frequencies of 54, 264, and 448 Hz can be observed from the power spectral densities of axial velocity, corresponding to the shedding vortex in the shear layer, the swirl frequency of processing vortex core (PVC), and the vortex induced by the PVC structure, respectively. The influences of vortex shedding and PVC structure are weak and inadequate to affect the overall flame stability.

ОБОСНОВАНИЕ ГРАНИЦ РЕЖИМОВ РАБОТЫ СИСТЕМ ГИБРИДНОЙ ВЕНТИЛЯЦИИ

The paper presents the results of a theoretical study of existing terms of hybrid ventilation. A classification of hybrid ventilation strategies has been drawn up: concurrent and changeover operations. Concurrent operation includes the sharing of mechanical and natural ventilation systems, for example, in the case of natural inlet and the removal of contaminated air from the room by axial roof fans; mechanical systems, equipped with low-pressure fans, used in conjunction with technologies aimed at increasing natural pressure (heat and wind inducement). Changeover operation includes seasonal work, night cooling and local alternating work. The analysis of climatic characteristics based on data from meteorological station 27612 (Moscow, VDNH) shows that the average temperature of outdoor air exceeds the requirement temperature for natural ventilation calculations for most of the year. Annual average air exchange factors for the period 2016-2020 are less than 50 %, which proves the need for a seasonal hybrid ventilation system. Based on the calculation of average monthly air exchange factors, the mechanical inducement is recommended from March to November.

Thermal Simulation of Power Lithium-ion Battery Module

Thermal management of power lithium-ion battery modules is very important to avoid thermal problems such as overheating and out of control, the study of thermal behavior of battery modules can provide guidance for the design and optimization of modules and thermal management. In this paper, a 3d thermal model of the power lithium-ion battery module is established based on STARCCM+ by using computational fluid dynamics (CFD) method, and a grid independence simulation test is used to determine the number of grids, the temperature distribution is analyzed under the condition of 1C charge current. The research results show that the internal temperature rises gradually with the charge going on, the temperature distribution of the cells is basically symmetrical. When the heat transfer coefficient is 5W/(m2⋅K) and the natural convective air inlet temperature is 300K, the module temperature uniformity is good. But because of the maximum temperature slightly higher than the temperature of thermal runaway, additional cooling methods need to be considered to cool the battery.

Geometry of natural and engineered tidal inlets

Tidal inlets are crucial landforms that control the exchange of water and sediment between the open sea and back-barrier basins. Despite the well-established relationship between tidal prism and inlet cross section area, some aspects of tidal inlet geometry remain unconstrained. What processes set their width to depth ratio (or aspect ratio)? What controls the presence of a single-thread versus a compound channel within the same inlet? Do these relationships change with engineering activities? These questions were investigated by compiling and analyzing a database with 226 inlets worldwide. We found that the aspect ratio has a weak dependency on tidal range and wave height. The aspect ratio varies by at least an order of magnitude, and this variability is likely associated with the variability in the widening process, e.g., the bank erodibility. Engineered inlets tend to have smaller widths and aspect ratios than natural inlets. Within natural inlets, multiple channels tend to form when the inlet width exceeds approximately 1 km. We developed an idealized barrier-inlet system using the detailed 2D hydro-morphodynamic model Delft3D to investigate the long-term morphological evolution of inlets. Two parameters greatly affect the aspect ratio: the transverse bed gradient factor for sediment transport (αbn) and the dry cell erosion factor (θsd), which allows for erosion of dry cells adjacent to a wet cell. Removing the dry cell erosion effectively “armors” the side of the inlets and thus produces inlets with a small aspect ratio, which resembles the geometry of engineered inlets. From model sensitivity analysis, we found that αbn = 5–10 and θsd = 0.3–1.0 provides inlet configurations that best agree with observations. Despite the dry cell erosion and the transverse transport parameters being a simplified representation of bank erosion processes, their calibration allows to reproduce realistic inlet aspect ratio.

Novel pressure inlet and outlet boundary conditions for Smoothed Particle Hydrodynamics, applied to real problems in porous media flow

In this work, new pressure inlet and outlet boundary conditions are developed for Smoothed Particle Hydrodynamics (SPH) that allow the natural development of in- and out-flow velocity profiles for any complex and irregular domain shapes and flow paths. The use of numerical methods to evaluate the permeability of real porous media is well established in the literature and SPH is a method that would seem ideally suited to such modelling. Examples applying SPH to real porous media are, however, scarce. A key limitation arises due to challenges associated with implementing natural inlet and outlet conditions on a highly irregular flow domain (as with porous rocks, bone, bioengineered ceramics, etc.). The method developed here enables generalised constant pressure open boundaries to be specified. This functions by controlling incoming or outgoing particle velocity to assure a target pressure and density is achieved at the theoretical boundary interface. The velocity correction term is derived from the SPH continuity density expression. New variations of no-slip and mirror boundaries are also presented. The developed method is shown to be highly robust and is implemented within a corrected kernel form of SPH (CSPH) to evaluate accuracy. Simulations are presented for several test cases including flow through a 2D channel junction, and permeability evaluation of an ideal 3D porous media across a range of porosities, and for 4 samples of porous trabecular bone taken from microCT scans. Results demonstrate excellent agreement with existing benchmarks, and with comparative results produced using the commercial ANSYS Fluent software package. The consistency of the developed boundary conditions enables accurate solution of a wide range of complex flow problems using SPH that has not been possible before.

Morphological modeling of long-term inlet channel evolution with an application to the Mundaú Lagoon inlet, Brazil

In the present study, a morphological model based on the main governing processes of inlet channels was developed for application in long-term simulations, requiring minimum data on forcing and only key information on the inlet geometry. The model considers the balance between the inlet sand transport due to tides and river flows and the longshore transport due to breaking waves. The resulting equations were numerically implemented and validated first through schematic simulations and then through an application to a real inlet. For the schematic simulations, the sediment transport rates in the inlet and alongshore were maintained constant and the behavior during evolution towards equilibrium was investigated and qualitatively assessed. Then, the model was applied to Mundaú Lagoon inlet (Brazil), a natural inlet sheltered by reefs and with a marked seasonality in river runoff. Thus, the model performance was validated for a complex setting over time scales of decades through comparisons with the observed inlet evolution determined from satellite images. The calculated results of inlet channel morphological evolution exhibited satisfactory agreement with observations. The computational efforts were low making the model suitable for long-term simulations where many alternative scenarios may be explored in a probabilistic manner. In conclusion, the developed model yielded robust and reliable simulation results having the potential for use in the assessment of long-term inlet channel evolution.

Modeling tidal hydrodynamic changes induced by the opening of an artificial inlet within a subtropical mangrove dominated estuary

The mangrove-estuarine system of Marismas Nacionales, Mexico is considered the most extensive wetland complex of the eastern Pacific coast. Originally, this large wetland was connected to the ocean solely through a natural inlet (Teacapan). However, in the early 1970s, it was decided that an artificial inlet (Cuautla Canal) will provide a second direct connection to the ocean that could help enhance local economic development. Unfortunately, it is believed that hydrological modification resulting from this inlet changed the hydrodynamics and thus massive loss of mangroves. Hence, the purpose of this investigation was to assess the tidal hydrodynamics before and after the canal’s construction and thus understand the potential negative impacts of such unsupervised coastal projects. Specifically, sea level elevation and tidal circulation velocities were simulated during flood and ebb currents using nonlinear numerical models for both inlets. Results indicated that sea level elevation and salinity increased from 2 to 35 cm and 0.5 to 35 PSU in the Agua Brava lagoon, respectively. Additionally, there was an overall increase of 0.6 m/s regarding the tidal current velocities, and thus it is probable that the Cuautla Canal contributed to the deterioration of the once Laguncularia racemosa dominated forests, which is slowly being replaced by Avicennia germinans, Rhizophora mangle, and extensive hypersaline floodplains. Consequently, such modeling could help in mitigating the impacts of future coastal developments in Mexico or elsewhere by helping in the prediction of the possible influence of tidal hydrodynamic changes on the subtropical coastal vegetation.

Recent evolution of the tidal prisms at the inlets of the western sector of the Ria Formosa, south coast of Portugal

The Ria Formosa is a coastal lagoon comprising six tidal inlets. The western sector encompassing three inlets, Ancão, Faro–Olhão and Armona is the most important one since it represents approximately 90% of the total tidal prism. The Ancão inlet is characterized by a cyclic eastward migration pattern, but until now the knowledge of the real impact of its dynamics in the last 20 years in terms of tidal prisms and interconnectivity between these three inlets is scarce. This work presents the most exhaustive data set acquired so far, comprising 25 field surveys led in the period 2004–2013 on the western sector of Ria Formosa. This provides a long-term analysis of the recent temporal evolution of the tidal prisms from the three inlets during a single migration cycle (18 years) of the Ancão inlet. It determines the relative contribution of the three inlets to the total prism of the western sector of Ria Formosa before the last artificial opening of the Ancão inlet. Results show that at Ancão inlet the tidal prism decreased in spring tide mainly due to its eastward migration. The other natural inlet, Armona inlet, depict a progressive narrowing responsible for the decrease of the tidal prism in neap tide while during the same tidal phase, at the Faro–Olhão inlet, the most important one in terms of exchanges, the tidal prism increased. Those alterations at the three inlets could be related to morphodynamic changes and morphological evolution and confirmed the strong interconnectivity between them to compensate the variations of their relative contributions to the total prism. The tidal prisms errors were low for all cases (< 10%) and confirm that, globally, there was an increase of the prisms with time.

The Fishing Village of McClellanville, South Carolina

The Fishing Village of McClellanville, South Carolina Vennie Deas Moore (bio) Click for larger view View full resolution "Moose," hardened by the sea, 1998. All photos in this essay are by Vennie Deas Moore, and are housed at the South Caroliniana Library, University of South Carolina. Copies of Deas Moore's photographs are exhibited at the Village Museum in McClellanville, South Carolina. [End Page 83] "The Fishing Village"An environment of stillnessA force field of uninterrupted time and spaceA place of tranquilityHeld in time —Vennie Deas Moore, 1999 mcclellanville, fishing village McClellanville, a seaside fishing village, was founded in the early 1850s by rice planters from the Santee Delta. The little village became the summer home of these wealthy planters, who left their plantations for a few months each year to escape illnesses like malaria. The village contained modest "shotgun" houses and some very fine, large homes of grand architectural detail. Several oyster and crab factories were built along Jeremy Creek. Here, I've gathered photographs and my journal entries from 1998 to 2010, as well as the thoughts of my fellow author and colleague William "Billy" Baldwin. This is my humble attempt to capture a vanishing culture in the fishing village of McClellanville, South Carolina.1 the salt marsh In the South Carolina Lowcountry lie alluvial regions and much swampland. The coast is a labyrinth of bays, inlets, and streams draining into the rivers from the mainland. North of Georgetown, a half-moon of unbroken beach extends to the North Carolina boundary, and south of Georgetown, to the Savannah River, two thirds of the coastline is a border of barrier islands with lovely beaches. The salt rivers separating these islands from the mainland furnish a safe inland waterway from Winyah Bay to Savannah. The Intracoastal Waterway runs parallel to the Atlantic Ocean. Some lengths consist of natural inlets, saltwater rivers, bays, and sounds; others are artificial canals. It provides a navigable route along its length without many of the hazards of travel on the open sea. South Carolina salt marshes are flat, expansive landscapes of green during the summer and brown during the winter. At low tide, creeks sketch zigzagging scenes. As high tide comes, dark waters flow into the paddy. To view this from above is breathtaking, yet the wetland can be more hostile than beautiful. The cane-like marsh grass beats your body. Walking the spongy gray bogs along the massive salt marsh requires caution. The oozing mud clings to your feet and sinks you to the waist. The abundance of food in the marsh sustains shrimp, crabs, oysters, and fish. These inhabitants must maintain a salt balance. Mud dwellers burrow into the [End Page 84] mud at high tide to avoid predators. At low tide, they move over the muddy surface for feeding. The mud is a hazard as well as a haven. Lack of oxygen is a problem at low tide, when the burrows become dry or fill with stagnant water. While most creatures can adapt to slight changes in salinity, the water in the marsh is subject to abrupt changes. During storms, salinity at high tide approaches that of seawater, while after a heavy rain, particularly at low tide, the water of the estuary may be almost fresh. Stationary or sessile animals, such as oysters and clams, are forced to slow their metabolisms to reduce their oxygen needs. Click for larger view View full resolution Small shrimp boat at the Santee Delta, 2000. Traditional fishing ways here are as diverse as the coastal waterways. Of the more than 150 species of saltwater fish inhabiting the coastal waters, some twenty are valuable for food, as are economically important invertebrate fauna, including shrimp, oysters, and crabs. According to Billy, McClellanville native Jack Leland has said that, when he was a boy in the 1920s, each Saturday morning Big Creek would be lined with black families in oyster bateaus, gathering their seafood for the week, casting, picking oysters, fishing for croaker and spot. Long Creek, which entered in the edge of the Bay, was called the Psalm because it was the answer to people's prayers. Jeremy Creek runs through Cape Romain. Along the...

The ‘Voordelta’, the contiguous ebb-tidal deltas in the SW Netherlands: large-scale morphological changes and sediment budget 1965–2013; impacts of large-scale engineering

AbstractThe estuaries in the SW Netherlands, a series of distributaries of the rivers Rhine, Meuse and Scheldt known as the Dutch Delta, have been engineered to a large extent as part of the Delta Project. The Voordelta, a coalescing system of the ebb-tidal deltas of these estuaries, extendsc.10 km offshore and coversc.90 km of the coast. The complete or partial damming of the estuaries had an enormous impact on the ebb-tidal deltas. The strong reduction of the cross-shore directed tidal flow triggered a series of morphological changes that continue until today. This paper aims to give a concise overview of half a century of morphological changes and a sediment budget, both for the individual ebb-tidal deltas and the Voordelta as a whole, based on the analysis of a unique series of frequent bathymetric surveys. The well-monitored changes in the Voordelta, showing the differences in responses of the ebb-tidal deltas, provide clear insight into the underlying processes. Despite anthropogenic dominance, knowledge based on natural inlets can still explain the observed developments. Complete damming of the three northern estuaries Brielse Maas, Haringvliet and Grevelingen resulted in a regime shift, from mixed-energy to wave-dominated, and sediments are transported in landward and downdrift direction. This results in large morphodynamic changes – sediments are redistributed from the delta front landward – but small net volume changes – a 0.1–0.2 × 106m3a−1increase in volume over the period 1965–2010 – since the dams block sediment transport into the estuaries. Sediment volume losses of 106m3a−1are observed on the ebb-tidal delta of the partially closed Eastern Scheldt and still open Western Scheldt estuary. As a result of a reduction of the estuarine tide in the mouth of the Eastern Scheldt, the north–south-running North Sea tidal wave has gained impact on its ebb-tidal delta, which causes morphological adjustments and erosion of the Banjaard shoal area. Moreover, the Eastern Scheldt ebb-tidal delta delivers sediment to its neighbours. The stable ebb-tidal delta configuration in the Western Scheldt, despite major dredging activities, illustrates that these large inlet systems are robust and resilient to significant anthropogenic change, as long as the balance between the dominant hydrodynamic processes (tides and waves) does not alter significantly.

Discriminating between natural and human-induced shifts in a shallow coastal lagoon: A multidisciplinary approach

Abstract Coastal lagoons across the globe are increasingly experiencing undesired and sudden changes caused by human disturbances. Nevertheless, little is known about how long-term natural dynamics and anthropogenic impacts interact to drive the systems to their current state. This study discriminated natural- and human-induced changes in a shallow coastal lagoon near Punta del Este, Uruguay, using a multidisciplinary approach. The genesis of the water body resulted from a Middle Holocene marine transgression circa 6000 yr cal BP. From this time to about 4400 yr cal BP, a comprehensive set of proxies revealed a highly variable scenario, with alternating lagoon states linked to climatic variability. A Late Holocene hiatus was also identified in the sediment profile, linked to the barrier and inlet formation that caused a predominance of erosion over net deposition. Results showed that anthropogenic disturbances modified the landscape substantially and shifted the entire watershed to a previously unknown and undesired state. A freeway constructed in 1955 AD subsequently closed the lagoon's natural inlet and transformed the coastal water body into an artificial reservoir. After such significant human impact, the lagoon experienced a sharp decrease in water surface area along with an intensification of the siltation/eutrophication processes, as inferred from multiproxy data. Findings of this study are useful to identify early signals of human disturbances in pristine or less impacted coastal systems to assist mitigation measures and/or restoration actions.

Comparative study on the ventilation mode of the residential building in Beijing area in winter

With the development of residential energy conservation technology, the air tightness requirement of the window is higher and higher. So in winter the cold penetration wind cannot satisfy the requirement of indoor personnel to fresh air. The common ventilation mode includes natural ventilation, natural inlet and mechanical exhaust, wall type ventilator with heat exchange, ventilation unit with heat exchange. Looking for energy saving, comfortable way of ventilation, the application effect of the way of ventilation is evaluated in air distribution and comfort performance and the initial investment by FLUENT software. The conclusion is that the mode of ventilation unit with heat exchange has higher superiority compared with the others.

Reopening of a Remote Tidal Inlet Increases Recruitment of Estuarine-Dependent Nekton

Cedar Bayou, a natural tidal inlet, was recently dredged to allow for direct water exchange between the Gulf of Mexico and Mesquite Bay, TX, USA. We quantified changes in densities of juvenile nekton (fish, shrimps, and crabs) and community structure in Mesquite Bay after Cedar Bayou was reopened by collecting samples at both control and impact sites using an epibenthic sled 1 year before (October 2013–April 2014) and after (October 2014–April 2015) opening. Significantly higher densities of total nekton were observed at the impact sites after opening using a before-after control-impact design. Red Drum (Sciaenops ocellatus), Atlantic Croaker (Micropogonias undulatus), post-larval penaeid shrimps (Farfantepenaeus aztecus, F. duorarum, and Litopenaeus setiferus), and Blue Crabs (Callinectes sapidus) were significantly more abundant at impact sites after Cedar Bayou was opened. Multivariate analysis showed a significant change in impact site communities after opening and was driven by an increased presence of estuarine-dependent species. Overall, this study demonstrates that opening tidal inlets, such as Cedar Bayou, and reconnecting Mesquite Bay to the Gulf of Mexico increased the presence of numerous estuarine-dependent species, many of which were not present or occurred at very low densities prior to reopening. Thus, reestablishing the historical connectivity between a productive estuary and the open Gulf of Mexico via Cedar Bayou should reinstitute natural nekton recruitment processes important to the Aransas, Mesquite, and San Antonio Bay regions.

Environmental assessment of Mangrove communities in Tarut Bay, Eastern Arabian Peninsula, based on multidisciplinary approach

Abstract. Tarut Bay contains some of the most important mangrove forests in the Arabian Gulf countries, which are facing significant anthropogenic pressures. A multidisciplinary approach based on remote sensing, fieldwork, and chemical analysis was adopted in order to identify the pressures facing the mangrove communities in Tarut Bay and subsequently evaluate its current environmental condition. The analysis focused on the 2011 to 2014 timeframe in particular. The results indicate that the mangrove communities in Tarut Bay cover currently around 11.32 square km. Two major mangrove cover changes were identified in the area during the studied period, with a net loss of around 0.675 square km happening in the interim. The analysis adopted the Normalized Difference Vegetation Index (NDVI) to evaluate the temporal change in vegetation concentration. Moreover, the study evaluated the overall pollution condition of 19 mangrove communities in Tarut Bay to be medium based on the Pollution Load Index (PLI). Nevertheless, some of the mangrove communities in Tarut Bay are very healthy while others are very polluted and require immediate action to improve their pollution status. The findings of this work led to recommending mangrove improvement measures to address further deterioration and disappearance of mangrove communities, including the re-opening of natural inlets and avoiding residential developments on the mangrove coast.

EVALUATION OF BEACH EROSION UP-DRIFT OF TIDAL INLETS IN SOUTHWEST AND CENTRAL FLORIDA, USA

The paper discusses the analysis of up-drift beach erosion near selected tidal inlets due to natural evolution and anthropogenic influence. Large scale beach erosion adjacent to tidal inlets occurs due to mixed conditions of natural inlet evolution and anthropogenic change. Typically, beach erosion is expected on the downdrift side of many inlets as they can present a littoral barrier and cause sand deficit to the beaches downdrift. This paper focuses on beach erosion on the up-drift side of several selected inlets in Southwest and Central Florida, USA. The analysis includes evolution of the selected tidal inlets from the time they were naturally opened to existing conditions. The analysis of these case studies indicated the role of ebb shoal features in stabilizing shorelines adjacent to inlets. In cases where up-drift beach erosion occurred, ebb shoals features were significantly asymmetric in shape or depleted below their equilibrium volumes.

Analysis for Different Positions of Nozzle on Air-Assisted Boom Sprayer

Natural wind, relative position between the nozzle and the outlet of the ram in the air-assistant spray have a great influence on performance. Air-assisted boom sprayer model is developed based on CFD. According to the data of the related parameters of the spray machine, variables of 3-D model were defined. With velocity of natural wind and inlet of the ram , the spraying flow keeping constant, the relative position between the nozzle and the outlet being a research variable, this article calculates the drift rate of the droplets respectively, then analyzes the results scientifically and gets the corresponding conclusion. At the same time, in order to confirm the reliability of the simulation results, this paper makes an experiment, which is done in Shandong agricultural university spray performance laboratory. Studies have shown that drift rate is significantly lower when the nozzles located under outlet position than on the downwind or the upwind .

CFD Simulation of Gas Distributor with Two Chambers

This paper investigated a new type of gas distributor with two chambers by CFD software. The distributor has a natural gas inlet and nine nozzle outlets. For the investigation of this project, the mass flow rate of the distributor was analyzed in this paper to provide a way to optimize the structure of distributor. The N-S equations approached with the RNG k-ε turbulence model and the discretization were employed second order upwind. The simulation results will provide a number of useful suggestions and references for the further design.

Exchanges of nutrients and chlorophyll a through two inlets of Ria Formosa, South of Portugal, during coastal upwelling events

The Ria Formosa is a shallow and multi-inlet coastal lagoon system in southern Portugal, with six permanent connections to the Atlantic Ocean. The western sector of Ria Formosa comprises three of the main inlets, Ancão, Faro-Olhão and Armona, which contribute ~90% of the total tidal prism of the lagoon. Of those three inlets, Ancão and Faro-Olhão supply the minimum and maximum contribution for these exchanges, respectively. Four field surveys were conducted at these two inlets during the upwelling season (from spring to autumn) to determine the influence of upwelling process upon the hydrographic characteristics in spring tidal conditions: i) spring 2009 (Ancão inlet), ii) autumn 2011 (both inlets) and iii) spring 2012 (Faro-Olhão inlet). Water samples were collected hourly (at three levels), along complete semi-diurnal tidal cycles, to determine chlorophyll a (chl a) and nutrient concentrations. At the same time, the water velocity was measured along the cross section to estimate the tidal prism, nutrients and chl a transports. Ancão inlet contributes a much lower volume to the total tidal prisms than Faro-Olhão inlet. The temporal data variability reveals that chl a and nutrient dynamics through these inlets depends not only on the tidal influence and characteristics of the boundary waters, but also on the intensity of the atmospheric and oceanic forcings acting on the adjacent coastal zone. During pulses of coastal upwelling events, more evident in spring season (mainly in April 2009 and May 2012), the two inlets imported chl a and phosphate. In contrast, in the absence of upwelling conditions, due to wind reversals and/or long periods of wind relaxation, both inlets exported nitrate and phosphate, fertilizing the coastal ocean. However, the Ria Formosa is a highly complex hydrodynamic system, and hydrographic temporal differences can be expected at different scales as a result of changes in: i) morphological configuration of the natural inlets, ii) interconnectivity of channels, and iii) the seasonal meteorological and oceanographic conditions.

An Evaluation of Seawater Pumped Hydro Storage for Regulating the Export of Renewable Energy to the National Grid

A seawater inlet with a surface area of 6 km2 was assessed for the potential to be used as a 100 MW, low head, high flow, sea water pumped hydro energy storage system. The capital cost was estimated to be recouped after a number of years and the plant has a predicted energy storage capacity of 320 MWh.National and international policies are driving the increased penetration of solar and wind energy onto the electricity networks, in an effort to reduce carbon emissions. Transmissions System Operators depend on ancillary services such as spinning reserve from thermal generators or pumped hydro systems to enhance grid stability. The increased penetration of renewable energy onto the electricity grid is driving a demand for greater capacity in the area of energy storage.This research presents a case study, which is a technical and economical appraisal of using an inland sea water reservoir to store energy. This project involves building a seawater dam around an existing natural inlet, and placing turbines at the mouth of the inlet. As part of the study an evaluation of current pumped hydro, seawater storage, and tidal barrages was carried out. The optimum design of the low head, high flow rate seawater energy storage facility was determined for the seawater inlet and different scenarios for the optimum head and flow rates are presented for analysis.Using low-head, high-flow seawater storage near the coast, greatly reduces the danger of contamination of inland freshwater supplies, thus reducing the environmental impact of pumped seawater energy storage.This research indicates that sea water pumped hydro energy storage with a high flow rate and low head is technically and economically feasible for increasing the ability of national grids to allow high penetration of intermittent renewable energy.