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Tidal stream turbines are becoming an affordable option for harvesting sustainable energy in coastal areas. They can be retrofitted in barrages, providing an integral solution for flood protection and emission-free power generation, within environmental constraints. To optimize the turbine-barrage configuration with respect to these objectives, simulation tools are needed to predict the efficiency of the turbines as well as their impact on the adjacent tidal system. These tools should be based on an accurate representation of the underlying flow processes, which cover a wide range of spatial scales — from meters at the barrage and turbines to tenths of kilometers in the tidal basin. This article presents the development of such a tool by linking an analytical model for turbine fences in barrage gates to a regional flow model. The turbine model is validated with experimental data, and data from a thoroughly monitored tidal energy pilot project. Simulations reveal how clustering the turbines in small arrays can increase their efficiency, owing to array blockage effects, with only little effect on the tidal exchange. We also demonstrate the potential of using turbine fences to manipulate the tidal jet, issued from the barrage, with benefits for coastal — and wildlife protection in the basin. The presented research helps understanding how turbine fences in barrages can be configured with high energy yield and calculated impact to the environment. [Display omitted] • The performance of tidal fences in a barrage is governed by turbine-gate bypass flows. • Computing the performance involves the coupling of a range of spatial scales. • Using interior boundaries with a locally refined mesh proves valid for this purpose. • The method can be used to optimize the horizontal lay-out of tidal fences. • For the Eastern-Scheldt case the optimum is governed by array blockage and resistance. [ABSTRACT FROM AUTHOR]

Tidal stream turbines are becoming an affordable option for harvesting sustainable energy in coastal areas. They can be retrofitted in barrages, providing an integral solution for flood protection and emission-free power generation, within environmental constraints. To optimize the turbine-barrage configuration with respect to these objectives, simulation tools are needed to predict the efficiency of the turbines as well as their impact on the adjacent tidal system. These tools should be based on an accurate representation of the underlying flow processes, which cover a wide range of spatial scales — from meters at the barrage and turbines to tenths of kilometers in the tidal basin. This article presents the development of such a tool by linking an analytical model for turbine fences in barrage gates to a regional flow model. The turbine model is validated with experimental data, and data from a thoroughly monitored tidal energy pilot project. Simulations reveal how clustering the turbines in small arrays can increase their efficiency, owing to array blockage effects, with only little effect on the tidal exchange. We also demonstrate the potential of using turbine fences to manipulate the tidal jet, issued from the barrage, with benefits for coastal — and wildlife protection in the basin. The presented research helps understanding how turbine fences in barrages can be configured with high energy yield and calculated impact to the environment. [Display omitted] • The performance of tidal fences in a barrage is governed by turbine-gate bypass flows. • Computing the performance involves the coupling of a range of spatial scales. • Using interior boundaries with a locally refined mesh proves valid for this purpose. • The method can be used to optimize the horizontal lay-out of tidal fences. • For the Eastern-Scheldt case the optimum is governed by array blockage and resistance. [ABSTRACT FROM AUTHOR]

The Brazilian Equatorial Shelf (BES) is one among the macrotidal regions worldwide. This study used a high-resolution numerical configuration of the ocean model ROMS (Regional Ocean Modeling System) forced with realistic surface and lateral forcing, as well as with tides and river discharges. Tidal heights of more than 2 m were found in three regions in BES due to the large tidal amplification across the estuarine channels inside each region: Amazon, Pará, and Maranhão, and for a considerable time fraction. Heights between 4 and 5 m occurred with a frequency greater than 20%–30% in some regions. All hypothetical barrages proposed in this study were capable of an annual power production, in two-way mode, higher than La Rance (533 GWh year−1, two-way operation, France) and Sihwa (553 GWh year−1, flood-only operation, South Korea), except one with the same production as Sihwa barrage. The installation effort was evaluated using the Gibrat ratio, the ratio between the length of the barrage and its annual energy production. Among the proposed barrages, the most efficient ones have an annual power generation greater than 1500 GWh year−1 and a Gibrat ratios between 1.17 and 3.26, much lower than the Gibrat ratio of Sihwa tidal barrage. • Tidal Heights between 4 and 5 m occurred with a frequency greater than 20–30%. • Most proposed barrages had an annual power production higher than La Rance. • The most efficient proposed barrages had a lower installation cost than Sihwa. • Brazilian Equatorial Shelf is a source of clean energy to be explored. [ABSTRACT FROM AUTHOR]

• For making the tidal barrages cost-effective, new methods should be implemented to increase the produced power of them. For this purpose, this study suggests new techniques for optimally operating of the basin-based tidal units equipped to hydro-pumps. • According to the proposed technique, to increase the produced power and consequently the produced energy of the basin-based tidal units, at each time step, the number of turbines, sluices and hydro-pumps is optimally determined to yield the maximum produced energy of the generation unit using of different heuristic optimization approaches. • For satisfying the effectiveness of the suggested approach, optimal operating of a basin-based tidal unit installed on the estuary of Bacanga is done and impact of optimally dispatching of the turbines, sluices and hydro-pumps on produced energy of tidal unit is studied. Among different renewable energy-based power plants, barrage type tidal power plants with high installed capacity can be integrated in the bulk power systems. However, due to the high investment cost associated to the construction of the barrages and related components, barrage type tidal power plants are less developed than other renewable resources such as wind turbines and photovoltaic farms. In order to economize the production of electricity from barrage type tidal power plants, it is necessary to reduce the cost of generated electricity by these power plants with new methods. For this purpose, the plant is considered to generate the electricity in the ebb mode, and using the hydro-pumps the height of the water in the reservoir is increased in the flood state. Based on this fact, in this paper, to maximize the generated energy of the barrage type tidal power plant, an optimal design is proposed and the effective parameters of the plant including the number of turbines, the number and width of the sluices, the turbine diameters and the number of hydro-pumps are determined using of three optimization techniques including particle swarm optimization method, genetic algorithm and imperial competition algorithm. [ABSTRACT FROM AUTHOR]

The feasibility and sustainable operation of tidal lagoons and barrages has been under scrutiny over uncertainties with regards to their environmental impacts, potential interactions and energy output. A numerical modelling methodology that evaluates their effects on the hydro-environment has been refined to consider technical constraints and specifications associated with variable turbine designs and operational sequences. The method has been employed to assess a number of proposals and their combinations within the Bristol Channel and Severn Estuary in the UK. Operational challenges associated with tidal range power plants are highlighted, while also presenting the capabilities of modelling tools tailored to their assessment. Results indicate that as the project scale increases so does its relative hydrodynamic impact, which may compromise annual energy output expectations if not accounted for. However, the manner in which such projects are operated can also have a significant impact on changing the local hydro-environment, including the ecology and morphology. Therefore, it is imperative that tidal range power plants are designed in such a way that efficiently taps into renewable energy sources, with minimal interference to the regional hydro-environment through their operation. [ABSTRACT FROM AUTHOR]

China's major development and construction in utilization of tidal energy resources are concentrated in the area of Zhejiang Province. The development of tidal barrage in Zhejiang Province presented the ebb and flow trends. This paper introduced the resource status of tidal energy in Zhejiang Province. The five development stages of tidal barrage technology and the profiles of tidal power plant (TPP) in operation were reviewed, and problems and experiences were discussed. Some available future works for the development of tidal barrage were also proposed. The direction of utilizing tidal potential energy in the future is to update the generating units, improve construction skills and run optimization of operation in order to reduce costs and mitigate the impact on the environment. Actively exploring construction methods of medium to large-scale of TPPs are helpful to accelerate the utilization of tidal energy resources in Zhejiang Province and coastal areas in China. [ABSTRACT FROM AUTHOR]

In this work, an AI-Driven (autonomous) model representation of the La Rance tidal barrage was developed using novel parametrisation and Deep Reinforcement Learning (DRL) techniques. Our model results were validated with experimental measurements, yielding the first Tidal Range Structure (TRS) model validated against a constructed tidal barrage and made available to academics. In order to proper model La Rance, parametrisation methodologies were developed for simulating (i) turbines (in pumping and power generation modes), (ii) transition ramp functions (for opening and closing hydraulic structures) and (iii) equivalent lagoon wetted area. Furthermore, an updated DRL method was implemented for optimising the operation of the hydraulic structures that compose La Rance. The achieved objective of this work was to verify the capabilities of an AI-Driven TRS model to appropriately predict (i) turbine power and (ii) lagoon water level variations. In addition, the observed operational strategy and yearly energy output of our AI-Driven model appeared to be comparable with those reported for the La Rance tidal barrage. The outcomes of this work (developed methodologies and DRL implementations) are generalisable and can be applied to other TRS projects. Furthermore, this work provided insights which allow for more realistic simulation of TRS operation, enabled through our AI-Driven model. [Display omitted] • A generalisable AI-Driven model for the La Rance tidal barrage is developed. • Methodologies for parametrising La Rance's hydraulic structures are introduced. • A 0D model representation for La Rance is validated against experimental data. • The AI-Driven La Rance model showcases similar behaviour to the real operation. [ABSTRACT FROM AUTHOR]

Continental carbonates are currently of high interest for the oil and gas industry, as they have proved to be good reservoir rocks in Brazil and Angola offshore oil fields. In this article, a tufa system in which continental carbonates formed mainly in the Pliocene (Rambla Becerra Tufa System, Guadix Basin, Betic Cordillera, S. Spain), is described in detail, and a model proposed for its formation and evolution through time. Several stages of tufa growth have been identified in the field, intercalated between stages of progradation of alluvial fan sediments. The tufa system connects laterally with the fluvial system developed in the axial valley of the Guadix Basin during the Pliocene and the Pleistocene, indicating that the tufa formation was coetaneous with the periods of lateral expansion of the fluvial system floodplain, that in previous works have been interpreted as more humid stages and potentially warmer. The absence of extraclasts in the tufa sediments points to the low activity of the alluvial fans during the tufa formation and therefore supports the idea that the main tufa growth happened during more humid stages, and the alluvial fans developed further during the more arid periods, which is consistent with other recent findings in the Guadix Basin. The tufa growth is represented by four main stages, the second one bearing the best example to study as a potential reservoir analog, as the main outcrop is a discrete body with a specific geometry and facies distribution. This main outcrop is a mound-shaped tufa build-up formed by prograding sigmoids of clastic tufa, interpreted as the ramp-like buttresses developed after a barrage in a barrage tufa system. From a preliminary isotopic study of the carbonates forming the barrage tufa system and by comparison with other tufas and travertines, the oxygen and carbon stable isotopes point to an intermediate situation between a palustrine tufa and a travertine. This information, when added to the sedimentological data, supports the idea that water feeding the tufa system probably had different sources: a meteoric one, coinciding with the surface runoff and a groundwater one, probably in the form of springs fed by groundwater from the nearby aquifers that still exist in the Mesozoic carbonates that form the External Zones of the Betic Cordillera in the area. [ABSTRACT FROM AUTHOR]

Worldwide, tidal barrages reduce aquatic habitat connectivity and limit fish movements, especially for diadromous migrating species. Providing fish passage at these structures is crucial but technically and economically challenging. We measured the performance of a navigation lock, employed as a single-chamber vertical-slot fish pass, at a tidal barrage by the mouth of a tributary of the River Ouse, NE England. In autumn 2015, 265 European river lamprey Lampetra fluviatilis were tagged with Passive Integrated Transponders (PITs) and released in 11 replicate trials ( n = 157 in lock, n = 108 immediately below lock). Fifty nine lamprey were double tagged with PIT and acoustic tags and released in the Ouse, 350 m downstream of the barrage. The percentage of lamprey attempting to pass the upstream gates during PIT trials was moderate to high (55 and 93% for lamprey released below, and in the lock, respectively). Passage efficiency, for lamprey attempting to pass the upstream gates, was also high (average of 66% for releases in lock, 78% for releases below lock). Ninety percent of lamprey, released below the lock and attempting to migrate upstream passed the entire lock in <128 min following release. However, acoustic-tagged lamprey displayed poor attraction to the lock under prevailing high river-discharge conditions. Overall, 36% of acoustic-tagged lamprey attempted to pass the barrage, mostly comprising lamprey released at low tide (cf. high tide), generating a high passage efficiency of 76% (16/21). However, 15 individuals passed through the sluices and only one used the lock. Nevertheless, using navigation locks as fishways has the potential to provide increased access between estuarine and river habitats for a range of biota, including those with poor swimming performance, but effectiveness is dependent on managing water discharge routes. Future studies using different operating protocols, especially to improve fish attraction under different environmental conditions and for a range of species, are encouraged. [ABSTRACT FROM AUTHOR]

The regular and predictable nature of the tide makes the generation of electricity with a tidal lagoon or barrage an attractive form of renewable energy, yet storm surges affect the total water-level. Here, we present the first assessment of the potential impact of storm surges on tidal-range power. Water-level data (2000–2012) at nine UK tide gauges, where tidal-range energy is suitable for development (e.g. Bristol Channel), was used to predict power. Storm surge affected annual resource estimates −5% to +3%, due to inter-annual variability, which is lower than other sources of uncertainty (e.g. lagoon design); therefore, annual resource estimation from astronomical tides alone appears sufficient. However, instantaneous power output was often significantly affected (Normalised Root Mean Squared Error: 3%–8%, Scatter Index: 15%–41%) and so a storm surge prediction system may be required for any future electricity generation scenario that includes large amounts of tidal-range generation. The storm surge influence to tidal-range power varied with the electricity generation strategy considered (flooding tide only, ebb-only or dual; both flood and ebb), but with some spatial and temporal variability. The flood-only strategy was most affected by storm surge, mostly likely because tide-surge interaction increases the chance of higher water-levels on the flooding tide. [ABSTRACT FROM AUTHOR]

Korea has developed various new and renewable energy resources since 2000 due to increasing demand for Green Energy around the world. Because the west coast of Korea has an extreme tidal range, many research projects aimed at harnessing tidal energy have been conducted there successfully. Though the study of Dynamic Tidal Power (DTP) was started as a new tidal energy source about 20 years ago, its characteristics are not yet fully understood. DTP has the potential to have less environmental impact than does a conventional barrage type tidal power generator. Its characteristics were analyzed in many test cases using a numerical model. The theoretical maximum tidal power of DTP became the same as the maximum tidal range by controlling the phase difference. This showed that DTP has great potential for a very successful future in the Yellow Sea. Moreover, DTP could provide an attractive energy source even in areas of lower tidal range than indicated in previous studies. [ABSTRACT FROM AUTHOR]

In this study, enhancements to the numerical representation of sluice gates and turbines were made to the hydro-environmental model Environmental Fluid Dynamics Code (EFDC), and applied to the Severn Tidal Power Group Cardiff–Weston Barrage. The extended domain of the EFDC Continental Shelf Model (CSM) allows far-field hydrodynamic impact assessment of the Severn Barrage, pre- and post-enhancement, to demonstrate the importance of accurate hydraulic structure representation. The enhancements were found to significantly affect peak water levels in the Bristol Channel, reducing levels by nearly 1 m in some areas, and even affect predictions as far-field as the West Coast of Scotland, albeit to a far lesser extent. The model was tested for sensitivity to changes in the discharge coefficient, C d , used in calculating discharge through sluice gates and turbines. It was found that the performance of the Severn Barrage is not sensitive to changes to the C d value, and is mitigated through the continual, rather than instantaneous, discharge across the structure. The EFDC CSM can now be said to be more accurately predicting the impacts of tidal range proposals, and the investigation of sensitivity to C d improves the confidence in the modelling results, despite the uncertainty in this coefficient. [ABSTRACT FROM AUTHOR]

The potential impacts of ebb-only (one-way) and flood-ebb (two-way) modes of operation of a tidal barrage on the eutrophication potential of the Severn Estuary were investigated in this study using the simple modelling approach adopted by the UK’s Comprehensive Studies Task Team (CSTT). The model predictions were compared against CSTT thresholds for assessing eutrophication in estuaries and coastal waters. For the no barrage scenario, as well as the ebb-only and flood-ebb operating modes, the estuary was found to be potentially eutrophic as the predicted equilibrium nutrient concentrations and potential maximum phytoplankton biomass chlorophyll concentrations exceeded the threshold limits. Potential maximum phytoplankton primary productivity under both ebb-only and flood-ebb operating modes were found to be noticeably higher than that for the no barrage scenario. This is believed to be due to a combination of increased water residence time and greater light availability behind the barrage. However, the conditions for phytoplankton production are likely to be more favourable under ebb-only operating mode as the potential for maximum phytoplankton primary production was found to be significantly increased under ebb-only operating mode, with largely decreased suspended particulate matter concentration compared to flood-ebb operating mode where only a small reduction in suspended particulate matter concentration is predicted. [ABSTRACT FROM AUTHOR]

Marine renewable energy is playing an increasing significant role in many parts of the world, mainly due to a rise in the awareness of climate change, and its detrimental effects, and the increasing cost of natural resources. The Severn Estuary, located between South West England and South Wales, has a tidal range of up to 14 m which makes it the second highest tidal range in the world. There are a number of barrage proposals amongst various marine renewable energy schemes proposed to be built in the estuary. The Cardiff-Weston STPG (Severn Tidal Power Group) Barrage, which would be one of the world׳s largest tidal renewable energy schemes if built, is one of the most publicised schemes to-date. This barrage would generate about 17 TWh/annum of power, which is approximately 5% of the UK׳s electricity consumption, whilst causing significant hydro-environmental and ecological impact on the estuary. This study mainly focuses on investigating the hydro-environmental impacts of the STPG barrage for the option of two-way generation, and compares this with the commonly investigated option of ebb-only generation. The impacts of the barrage were modelled by implementing a linked 1-D/2-D hydro-environmental model, with the capability of modelling several key environmental processes. The model predictions show that the hydro-environmental impacts of the barrage on the Severn Estuary and Bristol Channel, such as changes in the maximum velocity and reduction in suspended sediment and bacteria levels, were less significant for the two-way generation scheme when compared with the corresponding impacts for ebb-only generation. [ABSTRACT FROM AUTHOR]

Abstract: The study investigates the impact that construction of a Severn Barrage in the Severn Estuary, on the west coast of the UK, might have on local wave conditions. Implementation of a barrage will impact on tidal currents and water elevations in the wider region. There is strong tidal modulation of wave conditions under the natural regime and therefore barrage-induced changes to tidal conditions could affect wave modulation in the region. This paper uses Swan, an open source 3rd generation spectral wave model, to investigate the possible impacts of construction of a barrage on tidal modulation of the wave conditions. It is found that current variations, rather than water level variations, are the dominant factor in tidal modulation of wave conditions. Barrage implementation does not substantially change the modulation of the wave period or direction. However, barrage implementation does affect the tidal modulation of wave heights in the area of interest. The tidal modulation of the wave heights is generally reduced compared to the natural case; the peaks in the wave heights on an incoming tide are slightly lowered and there is lesser attenuation in wave heights on the outgoing tide. This modulation leads to net changes in the wave heights over one tidal cycle. For all of the tested wave conditions, this net change is small for the majority of the tested domain, namely to within ±5% of the no barrage case. There are some areas of greater change, most notably larger net increases in the wave heights near the North Somerset coast where the post-construction net wave height increase over a tidal cycle approach 20% of the pre-construction conditions. These changes do not impact coastal flooding because the wave height increase is not co-incident with high tide. Importantly, the maximum wave height is not increased and thus the likelihood of extreme events is not increased. The area of greatest reduction is between Swansea and Porthcawl. Changes over a neap tidal cycle show similar patterns of net change, but the modulation over the tidal cycle is different; primarily the magnitude of modulation is half that for the spring tide case and the shape is altered in some locations. [Copyright &y& Elsevier]

Abstract: Models for river avulsions have identified the ratio between down-valley and cross-valley slopes of channels as the triggering factors for the sudden channel shift but have remained untested in the field. The August 2008 avulsion of the Kosi River at Kusaha, 12km upstream of the Kosi barrage in Nepal, provided an opportunity to study a large-scale avulsion (~120km) for its causal factors and driving mechanisms. We used the SRTM-based digital elevation model and remotely sensed data coupled with field topographic mapping with a kinematic GPS and a Total Station to characterise a ~50-km-long stretch of the Kosi River. We have computed reach-scale avulsion threshold index (ATI) integrating SRTM-derived slopes and planform dynamics on a GIS platform. We show that several reaches along the Kosi River are avulsion-prone, including the Kusaha point that is consistent with the August 2008 avulsion. We suggest that apart from cross-valley and down-valley slopes, planform dynamics such as thalweg shift, sinuosity variation, and channel multiplicity significantly influence the avulsion threshold in alluvial reaches of the rivers such as the Kosi. [Copyright &y& Elsevier]

Abstract: This paper presents an investigation of the impacts of a Severn Barrage on the hydro-environment of the Bristol Channel and Severn Estuary using the Environmental Fluid Dynamics Code (EFDC) model with a recently developed Barrage module (EFDC_B). Details are given of a barrage module being implemented into the EFDC model to represent the various hydraulic structures, such as turbines and sluice gates, as deployed along the barrage line. Several cases, both with and without the barrage, have been simulated to investigate the potential changes on the peak water levels, minimum water depths and peak tidal currents arising from a barrage. The impacts of a barrage on the salinity concentration distribution have also been simulated in both 2D and 3D modes. The predicted results showed that the maximum water levels could be significantly reduced, especially downstream of the barrage and for much of the region in the Severn Estuary and that the minimum water depths would be changed so much that there would be 80.5 km2 loss of intertidal habitats due to the sitting of a barrage across the estuary. Likewise, the peak tidal currents would be considerably reduced, and by as much as a half in the middle of the main channel. The predicted salinity concentrations results indicated that at high water, the salinity concentrations would be reduced by 1–2 ppt downstream and upstream of the barrage and salinity concentrations in the region near Beachley would be reduced by up to 5 ppt, and that at low water, salinity concentrations would be reduced by 0.5–1 ppt in the middle of the Bristol Channel and by typically 0.5 ppt and 1 ppt downstream and upstream of the barrage, respectively. The predicted results also indicated that salinity concentrations downstream and upstream of the barrage would be under a stable state with slight oscillations all the time due to the effects of the barrage. A comparison between the salinity concentration distributions predicted by the 2D and 3D models indicated that the two models produced similar salinity distributions, especially in the Severn Estuary and in the region between the middle of the Bristol Channel and the seaward open boundary. [Copyright &y& Elsevier]

Abstract: While construction of the Aswan High Dam (AHD) has stopped concurrent flooding events, River Nile is still subject to low intensity flood waves resulting from controlled release of water from the dam reservoir. Analysis of flow released from New Naga-Hammadi Barrage, which is located at 3460km downstream AHD indicated an increase in magnitude of flood released from the barrage in the past 10years. A 2D numerical mobile bed model is utilized to investigate the possible morphological changes in the downstream of Naga-Hammadi Barrage from possible higher flood releases. Monte Carlo simulation analyses (MCS) is applied to the deterministic results of the 2D model to account for and assess the uncertainty of sediment parameters and formulations in addition to sacristy of field measurements. Results showed that the predicted volume of erosion yielded the highest uncertainty and variation from deterministic run, while navigation velocity yielded the least uncertainty. Furthermore, the error budget method is used to rank various sediment parameters for their contribution in the total prediction uncertainty. It is found that the suspended sediment contributed to output uncertainty more than other sediment parameters followed by bed load with 10% less order of magnitude. [Copyright &y& Elsevier]

Abstract: Some previous work has made optimistic claims about the potential energy gains that could be made by using pumping with tidal range structures (barrages, lagoons and offshore tidal impoundments). This paper explores the factors influencing whether such gains can be realised for positive head pumping (pumping once water levels have equalised), using 0-D modelling concepts. [Copyright &y& Elsevier]

The downstream region of the Kuantan River has a high potential of being affected by salinity issues according to research conducted nearly 40 years ago in studying the salinity effects on the freshwater intake in Kobat. The resulting results from the study then lead to the construction of a barrage in 1985 to prevent salt intrusion into the Kobat freshwater intake station area during low flow and high tides. However, salt intrusion problems were reported to occur in recent years. Thus, this research aims to: 1) determine salt intrusion extends in the Kuantan Estuary after the construction of the barrage; 2) calibrate and validate the Van der Burgh Coefficient K, and dispersion coefficient D in determining the salt intrusion pattern; and 3) compare the salinity pattern before and after the construction of the barrage. A 1-D analytical salt intrusion model was adopted in this study for the salinity analysis. Field measurements were conducted along the dry season at spring tide when the salinity travels furthest with a minimal amount of freshwater discharge. Salinity data was collected only up to the Kobat barrage by using the moving boat. The total salinity length at HWS obtained for 27th & 29th March 2017, 3rd October 2017, 7th March 2018 and 15th April 2018 are 21 km, 18.82 km, 21.05 km, 16.24 km, and 24 km, respectively. Results obtained from the salt intrusion simulation showed that the Van der Burgh Coefficient K for Kuantan Estuary is 0.45 and the dispersion ranged between 100 and 250 m2/s. Meanwhile, the comparisons of the newly surveyed salinity results with the previous research have indicated that the pattern of longitudinal salinity distribution has significantly changed after the construction of the barrage. The finding from the recent survey demonstrated the scatter distribution pattern compared to the gradually uniform pattern in the previous survey. This condition shows that the natural hydrodynamic process in the Kuantan Estuary has no longer in equilibrium condition and is unstable. The validation results obtained show good agreement between the simulated and observed salinity distribution in the estuary with low RMSE in the range 0.4 ppt–5.0 ppt and high NSE values ranges 0.97 to 1.00. This indicates that the model is reliable and can become an important tool for water managers in conducting salt intrusion studies for this area. • One dimensional analytical salt intrusion model can be applied to developed salinity profile in the Kuantan Estuary. • It is proven that the salinity distribution in the Kuantan Estuary no longer fulfil the pattern in undisturbed estuary. • The construction of barrage resultant in high inconsistency of salinity distribution at the area near to it. • Study provides a useful insight of the current salinity condition in the Kuantan Estuary. [ABSTRACT FROM AUTHOR]

The downstream region of the Kuantan River has a high potential of being affected by salinity issues according to research conducted nearly 40 years ago in studying the salinity effects on the freshwater intake in Kobat. The resulting results from the study then lead to the construction of a barrage in 1985 to prevent salt intrusion into the Kobat freshwater intake station area during low flow and high tides. However, salt intrusion problems were reported to occur in recent years. Thus, this research aims to: 1) determine salt intrusion extends in the Kuantan Estuary after the construction of the barrage; 2) calibrate and validate the Van der Burgh Coefficient K, and dispersion coefficient D in determining the salt intrusion pattern; and 3) compare the salinity pattern before and after the construction of the barrage. A 1-D analytical salt intrusion model was adopted in this study for the salinity analysis. Field measurements were conducted along the dry season at spring tide when the salinity travels furthest with a minimal amount of freshwater discharge. Salinity data was collected only up to the Kobat barrage by using the moving boat. The total salinity length at HWS obtained for 27th & 29th March 2017, 3rd October 2017, 7th March 2018 and 15th April 2018 are 21 km, 18.82 km, 21.05 km, 16.24 km, and 24 km, respectively. Results obtained from the salt intrusion simulation showed that the Van der Burgh Coefficient K for Kuantan Estuary is 0.45 and the dispersion ranged between 100 and 250 m2/s. Meanwhile, the comparisons of the newly surveyed salinity results with the previous research have indicated that the pattern of longitudinal salinity distribution has significantly changed after the construction of the barrage. The finding from the recent survey demonstrated the scatter distribution pattern compared to the gradually uniform pattern in the previous survey. This condition shows that the natural hydrodynamic process in the Kuantan Estuary has no longer in equilibrium condition and is unstable. The validation results obtained show good agreement between the simulated and observed salinity distribution in the estuary with low RMSE in the range 0.4 ppt–5.0 ppt and high NSE values ranges 0.97 to 1.00. This indicates that the model is reliable and can become an important tool for water managers in conducting salt intrusion studies for this area. • One dimensional analytical salt intrusion model can be applied to developed salinity profile in the Kuantan Estuary. • It is proven that the salinity distribution in the Kuantan Estuary no longer fulfil the pattern in undisturbed estuary. • The construction of barrage resultant in high inconsistency of salinity distribution at the area near to it. • Study provides a useful insight of the current salinity condition in the Kuantan Estuary. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, there have been growing international challenges relating to climate change and global warming, with a conflict developing between the need to create a low-carbon economy and rapid depleting reserves of fossil fuels. In addition to these challenges there continues to be the added complexity of a significant global increase in energy demand. Marine renewable energy from tidal barrages is carbon-free and has the potential to make a significant contribution to energy supplies now and in the future. Therefore, it is appropriate to evaluate the total energy that can be extracted from such barrages. In this study two different methods are proposed to estimate the total annual energy output from a barrage, including a theoretical estimation based on the principle associated with tidal hydrodynamics, and a numerical estimation based on the solutions obtained from a 2D hydrodynamic model. The proposed Severn Barrage in the UK was taken as a case study, and these two methods were applied to estimate the potential annual energy output from the barrage. The predicted results obtained using the two methods indicate that the magnitude of the annual energy output would range from 13 to 16TWh, which is similar to the value of 15.6TWh reported by the Department of Energy and Climate Change, in the UK. Further investigations show that the total annual energy output would increase by about 15% if a higher discharge coefficient were to be adopted for the sluice gates, or if the turbine performance were to be improved. However, the estimated annual energy output could exceed the value of 16TWh if future technological advances in both sluice gate construction and turbine performance are included. [Copyright &y& Elsevier]

Abstract: This research investigated seepage under hydraulic structures considering flow through the banks of the canal. A computer model, utilizing the finite element method, was used. Different configurations of sheetpile driven under the floor of the structure were studied. Results showed that the transverse extension of sheetpile, driven at the middle of the floor, into the banks of the canal had very little effect on seepage losses, uplift force, and on the exit gradient at the downstream end of the floor. Likewise, confining the downstream floor with sheetpile from three sides was not found effective. When the downstream floor was confined with sheetpile from all sides, this has significantly reduced the exit gradient. Furthermore, all the different configurations of the sheetpile had insignificant effect on seepage losses. The most effective configuration of the sheetpile was the case when two rows of sheetpiles were driven at the middle and at the downstream end of the floor, with the latter sheetpile extended few meters into the banks of the canal. This case has significantly reduced the exit gradient and caused only slight increase in the uplift force when compared to other sheetpile configurations. The present study suggests that two-dimensional analysis of seepage problems underestimates the exit gradient and uplift force on hydraulic structures. [Copyright &y& Elsevier]

Abstract: The Pleistocene deposits of the valley of the River Piedra (NE Spain) are represented by thick tufas with small amounts of detrital material; the development of these deposits correlates with marine isotopic stages 9, 7, 6, and 5. The sedimentary scenario in which they formed mostly corresponded to stepped fluvial systems with barrage-cascade and associated dammed areas separated by low gradient fluvial stretches. Mapping and determining the sedimentology and chronology of these deposits distinguished two main episodes of fluvial diffluence that originated as a result of the temporary blockage of the river — a consequence of the vertical growth of tufa barrages in the main channel. In both episodes, water spilt out toward a secondary course from areas upstream of barrages where the water level surpassed the height of the divide between the main and secondary course. As a consequence, extensive and distinct tufa deposits with very varied facies formed over a gently inclined area toward and, indeed, within the secondary course. The hydrology of this secondary course was episodic, fed only by surface water. The two diffluence episodes detected occurred during MIS 7 and 7–6 and were interrupted by incision events, reflected by detrital deposits at the base of each tufa sedimentation stage in the main channel. Incision, which caused the breakage of the barrages, allowed water to again flow through the main channel. No evidence of diffluence was seen in any younger (MIS 5 to present-day) tufa deposits. The proposed diffluence model might help explain other carbonate fluvial systems in which (1) tufas appear in areas with no permanent water supply, and (2) tufas are absent over extensive areas despite conditions favourable to their formation. [Copyright &y& Elsevier]

Abstract: The Severn Estuary has a spring tidal range approaching 14m, which is among the highest tides in the world. Various proposals have been made regarding the construction of a tidal barrage across the estuary to enable tidal energy to be generated. The aim of the current study is to investigate the impact of constructing a tidal barrage on the hydrodynamic processes in the Severn Estuary using a numerical model. A two-dimensional hydrodynamic model based on an unstructured triangular mesh has been used in this study. The model employs a TVD finite volume method to solve the 2D shallow water equations, with the numerical scheme being second-order accurate in both time and space. The model has been calibrated by comparing model predictions with observed tidal levels and currents at different sites, for typical spring and neap tides, and it has also been verified using tidal level time series at four tide gauging stations measured in 2003. In order to predict the hydrodynamic processes with a barrage, the model domain was divided into two subdomains: one each side of the barrage. Details were given of the method used for representing the various hydraulic structures, including the sluices and turbines, along the proposed Cardiff-Weston barrage. The impact of constructing the barrage on the water levels and velocities was then investigated using this model. Model-predicted hydrodynamic parameters, without and with the barrage, were analysed in detail. Model predictions indicated that with the barrage the mean power output could reach 2.0GW with up to 25GWh units of electricity being generated over a typical mean spring tidal cycle. At some cross-sections, the maximum discharges were predicted to decrease by 30–50%, as compared with the corresponding discharges predicted without the barrage. The model also predicted that with the barrage, the maximum water levels upstream of the barrage would decrease by 0.5–1.5m, and with the peak tidal currents also being reduced considerably. For different operating modes, complex velocity fields were predicted to occur in the vicinity of the barrage. [Copyright &y& Elsevier]

Abstract: The Severn Estuary has a spring tidal range approaching 14m and is regarded as having one of the highest tidal ranges in the world. Various proposals have been made regarding the construction of a tidal barrage across the estuary to enable tidal energy to be extracted. The barrage scheme originally proposed by the Severn Tidal Power Group (STPG) would be the largest project for tidal power generation in the world if built as proposed. Therefore, it is important to study the impact of different operating modes for this barrage on the tidal power output and flood inundation extent in the estuary. In this paper, an existing two-dimensional hydrodynamic model based on an unstructured triangular mesh has been integrated with a new algorithm developed for the estimation of tidal power output, which can account for three barrage operating modes, including ebb generation, flood generation, and two-way generation. The refined model was then used to investigate the impact of different barrage operating modes on the tidal power output and the associated extent of flood inundation along the Severn Estuary. Predicted results indicate that the mode of flood generation would produce the least electrical energy and cause a larger reduction in the maximum water levels upstream of the barrage. Two-way generation would provide an improvement to these conditions, and produce an equivalent amount of electricity to that from ebb generation, with a low installed capacity and a small loss of intertidal zones. Therefore, the mode of ebb generation or two-way generation would appear to be a preferred option for power generation, because both would offer benefits of acceptable electrical energy and reduced flood risk. [Copyright &y& Elsevier]

Abstract: Since the event of September 11, 2001 in New York City, many people started to speculate that the same type of attack could in future be brought against other installations. Indeed, the U.S. Nuclear Regulatory Commission decided to require for future plants to assess their resistance to the impact of a large civil airliner. Nuclear plant control authorities of other countries decided in a similar direction. The solutions to the technical problem is usually pursued in the direction of a reinforcement of external plant structures and, in some case, they may not be sufficient. Other solutions of more psychological nature have also been adopted. This paper aims at the demonstration that the use of barrage balloons, already adopted with success in both World Wars and also occasionally after these events, can afford a satisfactory solution to the protection problem at a reasonable cost. This solution is also applicable to existing plants. The history of barrage balloons is summarized. Modern technology offers electronic devices capable to detect in time an approaching threat and the paper describes a new barrage system based also on such new possibilities. If the aircraft crash problem is a real one or not for the next years, nobody knows for sure; however some considerations should be kept in mind: [•] The fact that an accident of this kind “anywhere” is an accident “everywhere” as usual; [•] The extremely uncertain political outlook worldwide, the peculiarities of the oil market and the possible nuclear renaissance. [Copyright &y& Elsevier]

Abstract: The Severn Estuary, located in the UK between south east Wales and south west England, is an ideal site for tidal renewable energy projects, since this estuary has the third highest tidal range in the world, with a spring tidal range approaching 14m. The UK Government recently invited proposals for tidal renewable energy projects from the estuary and many proposals were submitted for consideration. Among the proposals submitted and subsequently shortlisted were: the Cardiff–Weston Barrage, the Fleming Lagoon and the Shoots Barrage, all three of which are nationally public interest. Therefore a two-dimensional finite volume numerical model, based on an unstructured triangular mesh, has been refined to study the hydrodynamic impact and flood inundation extent, post construction, of all three of these proposed tidal power projects. The model-predicted hydrodynamic processes have been analysed in detail, both without and with the structures, including the discharge processes at key sections, the contours of maximum and minimum water levels, the envelope curves of high and low water levels, the maximum tidal currents, the local velocity fields around the structures and the mean power output curves. Simulated results indicate that: (i) although the construction of the Cardiff–Weston Barrage would have an adverse impact on a range of environmental aspects, due to there being approximately a 50% decrease in the peak discharge entering the upstream region, it would reduce the maximum water levels upstream of the barrage by typically 0.3–1.2m, which could be positive in respect of coastal flooding; (ii) the construction of the Fleming Lagoon would have little influence on the hydrodynamic processes in the Severn Estuary; and (iii) the construction of the Shoots Barrage would decrease the maximum water levels upstream of the M4 bridge by between 0.3 and 1.0m, but it could lead to an increase in the maximum water levels downstream of the barrage by typically 20–30cm. [Copyright &y& Elsevier]

Abstract: The Vaal River Barrage, situated on the south-eastern border of the Gauteng Province, has been part of the hydrological landscape of South Africa’s most populous and economically active region for more than eight decades. After its completion in 1923 the Barrage was compromised by the construction, upstream, of the Vaal Dam (1930–1933). Today the Vaal River Barrage is primarily a storage facility of sewage and industrial waste water. South Africa’s transition to a multi-racial democracy in 1994 saw a number of socio-economic and political transformations that affected the water infrastructure. In the field of sanitation infrastructure in particular, conditions have deteriorated to the extent that the health of people in many parts of the country is being compromised. Using the Vaal River Barrage as a case study, this article outlines the efforts by civil society to make the relevant government sectors aware of this hazardous state of affairs. particular attention is given to save our Vaal environment (SAVE), a non-governmental organisation, at the helm of an active campaign to reduce pollution in the Vaal River Barrage. [Copyright &y& Elsevier]

Finding the entrance into a fishway might be challenging for upstream migrating fish and especially so in large rivers. Auxiliary discharge, added into the downstream section of the fishway, will improve the attraction in the tailwater, but may impede passage in the fishway itself. In the present study we investigated a best practice design of an entrance channel with auxiliary water supply through a lateral screen in an experimental flume by means of hydraulic measurements and fish tests. Two screen sizes and angles and, relating thereto, two screen design velocities were compared and performed equally well. There was no difference in passage success for nase (Chondrostoma nasus), gudgeon (Gobio gobio), spirlin (Alburnoides bipunctatus), roach (Rutilus rutilus) and brown trout (Salmo trutta). The additional attempt to guide fish through the entrance channel by use of a slot which produced a more perceptible flow towards the upstream fishway section did not improve passage times of spirlin and brown trout. With a mean finisher rate of about 85%, which is a conservative assessment since it derives from an artificial, experimental situation, our flume layout turned out to be a good basis for a design recommendation. We suggest adding auxiliary discharge through a lateral screen with a design velocity of 0.4 ms−1 and we provide the necessary design specifications for geometry, hydraulics and screen arrangements in the entrance channel. • Adding auxiliary discharge into a fishway through a lateral screen allows efficient fish passage. • Inflow velocities perpendicular to the screen of 0.4 ms−1 can be recommended. • Five fish species successfully navigated the new entrance channel design. [ABSTRACT FROM AUTHOR]

Abstract: A new double-arch steel gate used as tidal barrage and sluice was adopted in the Caoe River Dam in China. It was a new application of a spatial structure in hydraulic gate to bear bilateral loading. To study the mechanical property of the gate, a scale-model cyclic test was conducted. The test data of the model under the bilateral designing load were analyzed and it was found that the load-bearing members mainly bore axial force and the value of axial force varied a little along the span. Thus the design of the gate was appropriate. The bearing capacity of the model was analyzed through load–deflection envelope curve. The curve was divided into three stages: the elastic stage, the local plastic stage and the failure stage by the local yield point and structural yield point. The local plastic strain in the joints had minor influence on the load–deflection curve of the structure before the joints were damaged. There were local yield strength and structural yield strength in the gate model and both of their values were bigger than that of the designing load. Therefore, the gate was safe enough for the projects. Arch-springing joints and the places where the main arches and minor arches were joined were the key joints because they were subject to damages. Moreover, fatigue analyses of the joints were performed and those which failed to meet the fatigue requirement were redesigned. [Copyright &y& Elsevier]

Abstract: An AMF infectivity study and spore viability assessment was performed on substrata obtained from gold and uranium mine tailings dumps (‘slimes dams’) in the North West and Free State provinces of South Africa. Three slimes dams in each region were categorized as recently vegetated (RV), old vegetated (OV) and never vegetated (NV), and dams then divided into five zones based on elevation above ground level, steepness and broad chemical differences. Rhizosphere samples were collected from two of three plant species common to all sites; Eragrostis curvula, Atriplex semibaccata and Cynodon dactylon, as well as from bare areas, in order to allow comparisons across all site categories because of the rarity of the grasses on the lower slope of NV dams. Infectivity was determined by the mean infection percentage method from a bioassay of the substrata using Eragrostis curvula cv Ermelo as a host plant. There was no difference in total infectivity between North West and Free State substrata, but within regions, there were differences in infectivity between rehabilitation ages, between zones, and between rhizosphere and bare areas. Toepaddock substrata and veld soil produced the highest total infection levels overall. On both dams and veld, total arbuscular levels differed between rhizosphere and bare substrata, and the percentage of arbuscules (max. 15.4%) and vesicles (max. 22.0%) as a proportion of total infection structures was low. A low correlation between infectivity and total spore numbers was also found. Spore numbers and the numbers of viable spores increased with zone down the slimes dams to the veld, and also differed within zones between rhizosphere and bare substrata with marked interactive effects. Substratum organic matter (SOM) levels differed between regions, and between zones within the North West region increasing with distance down the slopes to the veld, and were strongly correlated with total spore numbers. Substratum pH values and most AMF parameters were positively correlated in the order of RV>OV>NV dams, indicating that natural colonization of acidic NV sites by AMF is at very low rates, and that AMF colonizing RV slopes are not surviving the transition from RV to OV, with the associated increase in acidity, conductivity and decline in plant cover. Substratum conductivity differed between zones in both regions, with minor interaction between region and zone, and was negatively correlated with pH, AMF infectivity and total spore numbers. Our findings demonstrate that the ameliorant effects of liming and irrigation on substratum pH and conductivity are short-lived, but despite the physico-chemical constraints, a significant measurable AMF inoculum potential does exist on all substrata. Amelioration of tailings with organic matter and use of acid and salt-tolerant AMF would be expected to contribute to more persistent AMF communities and vegetation on gold and uranium slimes dams. [Copyright &y& Elsevier]

Abstract: Previously, we investigated the response of riparian vegetation to the installation of check dams along ephemeral Mediterranean rivers and we demonstrated significant changes in the form and structure of riparian vegetation around check dams that appeared to reflect changes in flow hydraulics and related fluvial sediment structures. In this paper we investigate the average properties of both bed sediment and riparian vegetation along transects immediately upstream, downstream and between three check dams along a single torrent headwater reach. Whilst there was overall sediment fining downstream through the study reach, the installation of check dams induced distinct local deviations from this downstream trend in both surface and subsurface sediments as well as in three synthetic parameters of the riparian vegetation (global canopy cover, weighted canopy height, species richness). No simple association was found between surface and subsurface bed sediment characteristics. The potential importance of fine sediment for water retention capacity in the subsurface was demonstrated through the application of a simple pedotransfer function. When transect properties of bed surface sediment (D50) and subsurface sediment (percentage finer than 0.25mm by weight) were jointly analysed with the three synthetic vegetation parameters using principal components analysis, the first two principal components accounted for 95% of the variation in the data, all of the variables apart from D50 were heavily positively loaded on the first principal component (74% of the variation in the data set), whereas D50 alone was heavily loaded on the second principal component (22% of the variation). Upstream transects were all strongly positively associated with the first principal component illustrating that a more diverse riparian vegetation cover with a better-developed and more complex canopy in this upstream location was strongly associated with higher proportions of fine subsurface sediments and had no association with the calibre of surface sediment. There were also highly significant positive simple correlations between all three synthetic vegetation parameters as well as both the percentage of fine sediment and estimated water retention capacity in the subsurface sediment across all transects. A description of typical changes in channel morphology around check dams places these significant associations between riparian vegetation and bed sediment into a broader environmental context. [Copyright &y& Elsevier]

Abstract: Previous studies suggest an association between dermal contact hypersensitivity and preterm delivery. We hypothesized that dietary protein deficiency produces cell-mediated immune hypersensitivity in pregnant animals and their offspring akin to those known to produce tissue damage. We compared the effects of feeding a 20% protein diet (controls) to those of feeding a 10% protein (deficient) diet ad libitum to pregnant BALB/c mice. We measured dermal contact sensitivity to 2,4-dinitrofluorobenzene (DNFB) by the increment in ear skin thickness (swelling) 72 h after immunization and parity by the number of viable pups delivered. Dams fed the protein-deficient diet ingested less food, gained less weight and delivered fewer viable pups than the dams fed the control diet. Greater DNFB-stimulated increment in ear skin thickness was found in the protein-deficient mothers and in their offspring than in the control mothers and their offspring. We conclude that dietary protein deficiency limits parity and induces immune hypersensitivity. These findings suggest the potential for dietary protein deficiency to activate a T-cell-mediated branch of the immune response that may put pregnant animals at risk for preterm delivery. [Copyright &y& Elsevier]

Abstract: The Naukluft Mountains on the eastern edge of the central Namib Desert contain numerous, largely inactive, fluvial tufas within headwater streams of the ephemeral Tsondab River which currently terminates in a vlei in the Namib sand sea. Extensive tufa barrage deposits have been mapped and described along the Brandfontein River, a small (6.5 km long) tributary of the Tsondab River. Here, a series of large barrages have developed along the river system which culminate in a large tufa cascade feature at the mountain front. Tufa facies at Brandfontein include cemented colluvial and fluvial gravels and boulders, moss tufas, as well as reed and root facies. The sequences provide evidence of several cut and fill phases which are interpreted as indicating alternating periods of tufa deposition and fluvial downcutting. The Brandfontein tufas are used to propose a three phase arid fluvial tufa deposition model in which erosive high magnitude, low frequency floods punctuate periods of quiescence and tufa deposition. Extensive downstream prograding ramped barrages and tufa cemented fluvial gravels are key components of this tufa deposition model, which illustrates the role of climate and topography in shaping tufa deposit morphologies. [Copyright &y& Elsevier]

Abstract: The impairments in the maternal behavior of ovariectomized sensitized females, relative to lactating dams, resemble those deficits found in lactating females after treatment with the D1/D2 DA receptor antagonist haloperidol, which interferes with maternal motivation. Therefore, it could be speculated that these behavioral deficits found in sensitized females and haloperidol-treated dams are due to a reduced motivation to interact with pups. In support of this hypothesis, we have found that both sensitized and haloperidol-treated lactating females exhibited remarkably similar impairments in the expression of all active maternal behaviors relative to lactating dams. Furthermore, these deficits were overridden when they were allowed to interact with 12h-isolated pups (demanding pups). Interestingly, lactating dams also improved their maternal behavior in the presence of demanding pups, and clearly chose demanding more than non-demanding pups in a preference paradigm. These data support the idea that the behavioral deficits of sensitized and haloperidol-treated lactating females are due to a reduced behavioral activation in response to the incentive cues from pups compared to lactating dams, and not because of a motor inability to express maternal behavior. These findings ultimately suggest that pups modulate the activity of DA system involved in the regulation of maternal behavior. [Copyright &y& Elsevier]

Abstract: Commercially farmed, hybrid striped bass – female white bass (Morone chrysops) crossed with male striped bass (Morone saxatilis) – represent a rapidly growing industry in the United States. Expanded production of hybrid striped bass, however, is limited because of uncontrolled variation in performance of fish derived from undomesticated broodstock. A 10×10 factorial mating design was employed to examine genetic effects and heritability of growth-related traits based on dam half-sib and sire half-sib families. A total of 881 offspring were raised in a common environment and body weight and length were recorded at three different times post-fertilization; parentage of each fish was inferred from genotypes at 10 nuclear-encoded microsatellites. Dam and sire effects on juvenile growth (weight and length) and growth rate were significant, whereas dam by sire interaction effect was not. The dam and sire components of variance for weight and length (at age) and growth rate were estimated using a Restricted Maximum Likelihood algorithm. Estimates of broad-sense heritability of weight, using a family-mean basis, ranged from 0.67±0.17 to 0.85±0.07 for dams; estimates for sires ranged from 0.43±0.20 to 0.77±0.10. Estimates of broad-sense heritability of growth rate (based on weight), using a family-mean basis, ranged from 0.69±0.12 to 0.82±0.09 for dams and from 0.69±0.13 to 0.81±0.08 for sires. Similar results were obtained with length data. Both genetic and phenotypic correlations between weight and length were close to unity. High genetic (0.98–0.99) and phenotypic (0.79) correlations between growth rates measured at two time intervals suggested that selection for growth rate at an early life stage could affect growth rate at a later life stage. Estimates of general combining ability (GCA) for growth rates differed significantly among dams and among sires, whereas estimates of specific combining ability (SCA) for each dam×sire combination did not differ significantly from zero. These results suggest that additive-effect genes contributed to the differences in juvenile growth. [Copyright &y& Elsevier]

Abstract: Locoweed (Oxytropis sericea) is a toxic plant commonly found on rangelands in the western United States. The locoweed toxin is an indolizidine alkaloid, swainsonine that causes neurological and systemic damage. The objective of this study was to determine if feeding of locoweed to pregnant ewes during days 100–130 of gestation would affect lamb behaviour shortly after birth. Twenty yearling nulliparous Columbia–Targhee ewes were divided into two treatment groups: loco ewes fed a 10% locoweed (O. sericea) pellet; control ewes were fed alfalfa pellets. Locoweed pellets contained 0.01mg/g swainsonine with a mean consumption of 0.32mgswainsonine(kg−1 day−1 ewe−1). Lambs from the two groups did not differ in birth weight (P =0.35), primarily because four control ewes had live twins whereas loco ewes had only live singles. Loco lambs were slower (P <0.01) in latency from birth to first successful standing event compared to control lambs (65min versus 22min, respectively). None of the loco lambs successfully nursed their dams up to 120min post partum, whereas control lambs all sucked successfully at 35min (P <0.01). Loco lambs had slower (P <0.01) times ( versus 11s, respectively) through a progressive maze on days 2, 4, and 6 compared to control lambs. Loco lambs were also much slower (P <0.01) to reach their dams during a barrier test at 12h post partum compared to controls (193s versus 42s, respectively). Control lambs discriminated their dams at 12h post partum whereas most loco lambs did not. In this same test, control lambs spent a higher percentage (P =0.03) of their time in close proximity to their dam compared to loco lambs . Lambs exposed to locoweed in utero for 30 days were intoxicated at birth. Lambs born to loco ewes showed impairments in their behaviour and appeared to demonstrate a weakened maternal infant bonding. Loco lambs would not have survived at birth without human intervention to assist in nursing. [Copyright &y& Elsevier]

Abstract: The self-potential method can be applied to evaluate the degree of water seepage into earth or rockfill dams. Spatial distribution of measured self-potential data can indicate possible anomalous water flow. Phenomena, such as piping, can be modelled as cylindrical bodies. Internal erosion can develop structures, which can be represented by a sphere or point source. Differential settlement in the dam structure occasionally creates horizontal fractures, which require equivalent geometrical body formula. An equation, which allows the calculation of a self-potential profile over a horizontal contact, was developed. This equation can also be applied to the inspection of water flow into horizontal drainage filters. When inverse interpretation returns bodies of relatively small amplitudes, then their probability can be tested statistically. A test, based on cross-correlation between a modelled curve and field data, can be used to evaluate their existence at a given probability level. An acceptance criterion is computed, using the concept of likelihood coefficient. The equation was applied to two case histories. The first is an example of water flow evaluation into a horizontal drainage filter. Several anomalous bodies were interpreted from residual self-potential data, i.e. from the difference between the theoretical response of the filter and the measured self-potential values, then, most of the interpreted bodies were statistically tested. The second case deals with detection and evaluation of a horizontal fissure. The interpreted parameters of the detected body corresponded well to a horizontal fracture found when the water level in the reservoir was lowered. [Copyright &y& Elsevier]

Abstract: In this study, the earthquake damage response of the concrete gravity dams is investigated with considering the effects of dam–reservoir interaction. A continuum damage model which is a second-order tensor and includes the strain softening behavior is selected for the concrete material. The mesh-dependent hardening technique is adopted such that the fracture energy dissipated is not affected by the finite element mesh size. The dynamic equilibrium equations of motion are solved by using the improved form of the HHT-α time integration algorithm. Two dimensional seismic analysis of Koyna gravity dam is performed by using the 1967 Koyna earthquake records. The effects of damage on the earthquake response of concrete gravity dams are discussed. Comparison of the Westergaard and Lagrangian dam–reservoir interaction solutions is made. The effects of viscous damping ratio on the damage response of the dam are also studied. [Copyright &y& Elsevier]

Abstract: The effect of single maternal subcutaneous (s.c.) injection of 0.12mg/kg diphenyl ditelluride, (PhTe)2, diluted in canola oil at days 6, 10 or 17 of gestation were evaluated in Wistar rats. The reduction of body weight gain was statistically significant at GD9, for the dams that received (PhTe)2, at GD6; at GD13, for the dams that received (PhTe)2, at GD10, and at GD20, for the dams that received (PhTe)2, at GD17, when compared to respective control groups. External and internal fetal soft tissues examination was performed on day 20 of gestation. Single maternal injection at day 10 of gestation resulted in appearance of malformation in fore- and hind-limbs, absent or short tail, subcutaneous blood clots, exophthalmia, hydrocephalus and absence of the cranial bone and cutaneous tissue in fetuses on day 20 of gestation. Besides, (PhTe)2 reduced fetal body and cerebral weight, kidney length, measurements of body dimension and provoked 73% of fetal mortality. Subcutaneous administration of (PhTe)2 on day 17 of gestation was associated with 94% mortality, hydrocephalus and edema. Histological evaluations of fetal brain demonstrated displaced brain tissue with absence of the cranial bone and cutaneous tissue when diphenyl ditelluride was administered in GD10. Histological evaluation of fetal head exposed at GD17 revealed a decrease of the brain volume with consequent dilation of the lateral ventricles and the adjacent tissues were thinner than that of control group tissues. No fetal changes were observed after administration of (PhTe)2 at day 6 of gestation. Thus, (PhTe)2 can be teratogenic to rat fetuses and toxic for dams. The late fetal stages of rat prenatal development appeared uniquely sensitive to organic tellurium exposure. [Copyright &y& Elsevier]

Abstract: In the process of flow deformation of an earth dam, the seepage force inside the dam plays a role as a driving force. The seepage force acts just like the gravitational force in terms of pushing soils away from their original locations after liquefaction is triggered. This paper draws attention to this seepage driving effect by presenting a set of fully coupled finite element analyses on the well-known San Fernando dams, with the objective of evaluating the impact of this seepage effect. The results indicate that while this effect is always there, its practical significance depends on a number of factors. In the case of the upper San Fernando dam, which experienced a significant, but restricted, downstream movement during the 1971 earthquake, the seepage driving effect was indeed significant. On the contrary, for the lower dam, which failed and slid into the upstream reservoir during the same earthquake, this seepage effect was relatively less pronounced. The detailed results of the analyses reveal the likely mechanisms of failure and deformation of the two dams and the likely cause behind the difference between their responses during the earthquake. [Copyright &y& Elsevier]

Modifications to estuaries through the construction of barrages alter the natural dynamics of inhabitant species by controlling freshwater inputs into those systems. To understand the effects of modified freshwater flows on a native scyphozoan jellyfish, Catostylus mosaicus , and to identify the environmental drivers of medusa occurrence, we analysed a 20-year observational dataset composed of 11 environmental variables and medusa presence/absence from 15 sampling stations located below the Fitzroy Barrage, in the Fitzroy River, Queensland. Major decreases in salinity (minimum salinity 0) occurred approximately 16 times during the 20-year period and medusae disappeared from the estuary following every major freshwater flow event. Salinity was identified as the most influential variable contributing to variation in the number of upper estuary sites reporting jellyfish. We then ran two laboratory experiments to test the following hypotheses: (i) prolonged decreases in salinity impair survival, pulsation, and respiration rates of C. mosaicus medusae; and (ii) transient decreases temporarily impair pulsation and respiration but medusae recover when salinity returns to normal levels. Medusae were unable to survive extended periods at extreme low salinities, such that they would experience when a barrage opens fully, but had significantly higher survival and recovery rates following smaller, transient changes to salinity that might occur following a moderate rainfall event. This demonstrates for the first time that modification of freshwater flow by a barrage regulates the population dynamics of an estuarine jellyfish, and highlights the need for robust, long term datasets, and to firmly embed experimental approaches in realistic ecological contexts. • Changes to freshwater flow by a barrage regulates the population dynamics of estuarine jellyfish. • Adult medusae cannot survive extended periods at extreme low salinities. • Adult medusae can survive and recover from short-term freshwater inputs. [ABSTRACT FROM AUTHOR]

The sudden rise in oil price in 1970s led various countries around the world to turn to renewable energy resources for electric power generation instead of fossil fuel-based power plants. Among different renewable power generations, wind and solar power plants have reached maturity and have been able to make a significant contribution to electricity supply. Tidal power plants have grown less due to high cost of investment. Hence, their share of electricity generation has been lower than that of wind and solar power plants. The potential of tidal energy is high and it is expected that tidal energy can play a key role for electricity production in the future power-system due to its accurate predictability. Two types of tidal power plants including barrage-type and current-type tidal power plants are developed for energy extracting from tides. The current-type tidal power plant generates electricity from the kinetic energy of tidal-currents in a way similar to wind-turbines, while the barrage-type tidal power plants are equipped with dam, barrage and reservoir in order to generate electricity from the potential energy of water stored in the reservoir. This paper proposes several methods for enhancing the generated power of barrage-type tidal power plants, which result in cost reduction of electricity generated by tidal power plants. At first, an optimum design procedure for calculating the optimum values of number of turbines, number of gates, sluice width, turbine tip diameter and turbine hub diameter is established based on the particle-swarm-optimization-algorithm, aiming to maximize the yearly produced energy. Then, the hourly optimum number of gates and turbines are calculated in the operation studies for maximizing the daily produced energy. Also, the utilization of hydro-pump is simulated as the third method of generated power enhancement. In addition, three operation modes of barrage-type power plants, including ebb-generation, flood-generation and double-effect generation are simulated and the best operation mode in terms of power generation is determined. [ABSTRACT FROM AUTHOR]

• Diffuse rainfall dominates groundwater recharge. • Groundwater baseflow is important for river ecology. • Evidence for localised groundwater recharge from canals and rivers. • Adequate flushing sustains low groundwater salinity. • Local redox conditions control groundwater As, Fe, Mn, NO 3 and U. The alluvial aquifer system of the Indo-Gangetic Basin (IGB) is one of the world's most important freshwater resources, sustaining humans and river ecosystems. Understanding groundwater recharge processes and connections to meteoric and surface water is necessary for effective water resource management for human and wider ecological requirements. Parts of the mid-Gangetic Basin, across eastern Uttar Pradesh and Bihar, are characterised by stable long-term groundwater levels, high annual rainfall, and limited historical groundwater use compared to parts of Northwest India for example. In this paper we use a combination of environmental tracers and hydrograph observations to characterise sources of recharge and groundwater-surface water interaction using a transect approach across the catchment of the River Gandak, a major barrage-regulated tributary of the River Ganga. Stable isotope results show that the dominant source of groundwater recharge, in the shallow (0–40 m bgl) Holocene and underlying Pleistocene aquifer system (>40 m bgl), is local rainfall. The shallow Holocene aquifer is also supplemented by local recharge from river and canal seepage and irrigation return flow in the upper and mid parts of the catchment. These observations are corroborated by evidence from detailed groundwater hydrographs and salinity observations, indicating localised canal, river and lake connectivity to groundwater. In the middle and lower catchment, river discharge is dominated by groundwater baseflow during the peak dry season when barrage gates are closed, which contributes to ecological flows for endangered river dolphins and gharial crocodiles. Groundwater residence time tracers indicate active modern recharge in the shallow alluvial aquifer system across the catchment. In the shallow Holocene aquifer elevated arsenic (As), iron (Fe), and manganese (Mn) exceeded WHO drinking water guidelines in a minority of sites, and uranium (U) and fluoride (F) concentrations approach but do not exceed the WHO guideline values. These observations varied across the catchment with higher As, Fe and Mn in the upper and mid catchments and higher U in the lower catchment. Groundwater salinity was typically between 500 and 1000 μS/cm, and isolated higher salinity was due to recharge from flood-plain wetlands and lakes impacted by evaporation. At present, the Gandak catchment has relatively high rainfall and low abstraction, which maintains stable groundwater levels and thus baseflow to the river in the dry season. Potential future threats to groundwater resources, and therefore river ecology due to the sensitivity to changes in baseflow in the catchment, would likely be driven by reductions in local monsoon rainfall, changes in water management practices and increased groundwater use. [ABSTRACT FROM AUTHOR]

This study investigates the macroscopic features of tidal farm layouts optimized to maximize power production in an idealized shallow channel with steady unidirectional flow. By varying the number of turbines and optimization constraints, numerical experiments were conducted using OpenTidalFarm, an open-source solver for tidal farm optimization using PDE-constraint gradient-based optimization. To alleviate the computational complexity for identifying a global optimum, a concept of quasi-global optimum was introduced, a local optimum that serves as a global optimum in a crude sense. From extensive numerical results, notable patterns in the shape of the quasi-global optimal layout were observed and explained by a nondimensional parameter, E , the ratio of the shortest hypothetical linear fence to the length of the lateral farm site constraint. The quasi-global optimal layout had a linear fence shape when E ≤ 1. The layout evolved into a downstream-concave parabola and subsequently into a V-shape as E increased beyond 1. Moreover, as more turbines were added to an array, the quasi-global optimal layout was no longer a single fence, and some turbines were separated from the main body. From the quantitative perspective, it is shown that the power production could be increased by up to 50% by tuning the optimization constraints. • Numerical experiments are undertaken to identify features of the optimal tidal farm layout. • A gradient-based optimization solver is used to maximize power production. • The shape of the optimal layout is dependent on a nondimensional parameter. • The optimal layout forms a downstream-wise concave barrage. • Adjusting the optimization constraints can improve power production by up to 50%. [ABSTRACT FROM AUTHOR]

Abstract: Tidal energy could convert into power on the basis of height difference (Tidal Barrages) and on the basis of flow speed (Tidal Current). The studies have shown that tidal barrages have some disadvantages concerning the environmental impacts and the limits of availability of economic sites. Tidal current seems to have much advantages concerning the environmental impacts and technology advancement and simplicity in application. This article discusses the tendency of utilization of small hydropower energy generation system in the coming decades regarding the concern of environment impacts and electricity needs worldwide. [Copyright &y& Elsevier]

• Remaining useful life and fatigue analysis of the blades have been discussed. • Most dangerous operating conditions for crack propagation have been determined. • The conclusions of these study could be contrasted with real cracks observed in prototypes. • CFD coupled with structural FEM considering an initial defect has been used. • Characteristics of pressure fluctuations and dynamic stresses have been presented. Tidal energy systems and specifically tidal barrages are renewable energy systems, that use the potential energy of tides to produce electricity. Actually, there are few tidal power stations operating, although recent studies show the potentiality of installing new units in a recent future due to the constant improvement of the technology related. As in other conventional hydropower systems, the runner is one of the critical components of the unit as it has to withstand an extreme wide range of relative head and two main operating modes (ebb and flood). Therefore, fatigue problems and undesirable failures are more likely to occur. Based on the analysis of a crack found in one of the blades of a prototype, this paper analyzes and discusses under which operating conditions the runner is more likely to suffer from fatigue problems. CFD and FEM simulation models have been used to determine the stress hotspots, which approximate very well the point where the real crack was initiated. Based on a probabilistic approach of an existing initial defect or flaw, the reliability of the blades, or the probability of not growing a crack and therefore last an infinite life, has been calculated for a wide range of operating conditions. While fatigue problems have been deeply discussed and analyzed in conventional turbines, the flow excitation characteristics in these units exhibit important differences and therefore the discussion and results provided in this paper could be useful for future designs and fatigue analyses of tidal turbines. [ABSTRACT FROM AUTHOR]

The construction of tidal barrages or dams across estuaries from which electricity is generated is an engineering concept decades old. Such projects have not always met with popular approval due to a mix of issues such as prohibitive capital costs and environmental problems from estuarine silting and flooding of upstream ecosystems. Steve Hastings, Woodshed Technologies Pty Ltd, Australia describes on an alternative tidal power concept that avoids the types of problems associated with tidal barrage systems. [Copyright &y& Elsevier]