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D.C., J.M., P.T. and S.W. acknowledge the financial support of the Tidal Stream Industry Energiser project (TIGER), which is co-financed by the European Regional Development Fund through the Interreg France (Channel) England Programme. A.A. acknowledges the support of NERC through the Industrial Innovation fellowship grant no. NE/R013209/2. D.G., B.S., T.S., D.W., R.W. and B.W. acknowledge EPSRC for supporting part of this work through EP/S000747/1. G.H. and C.S. acknowledge support by the Scottish government-funded Marine Mammal Scientific Support Programme MMSS/002 with additional resources from the Natural Environment Research Council grant nos. NE/R014639/1 and NE/R015007/1. M.L. acknowledges the support of the Smart Efficient Energy Centre (SEEC) at Bangor University, part-funded by the European Regional Development Fund (ERDF), administered by the Welsh Government, and the EPSRC METRIC fellowship grant no. (EP/R034664/1). L.M. acknowledges the financial support of an EPSRC PhD studentship award, grant no. EP/R513052/1(18-22). J.McN. acknowledges the financial support of R.Willden’s EPSRC Advanced Fellowship grant no. EP/R007322/1. S.N. acknowledges the support of SEEC (Smart Efficient Energy Centre) at Bangor University, part-funded by the European Regional Development Fund (ERDF), administered by the Welsh Government. This review provides a critical, multi-faceted assessment of the practical contribution tidal stream energy can make to the UK and British Channel Islands future energy mix. Evidence is presented that broadly supports the latest national-scale practical resource estimate, of 34 TWh/year, equivalent to 11% of the UK’s current annual electricity demand. The size of the practical resource depends in part on the economic competitiveness of projects. In the UK, 124 MW of prospective tidal stream capacity is currently eligible to bid for subsidy support (MeyGen 1C, 80 MW; PTEC, 30 MW; and Morlais, 14 MW). It is estimated that the installation of this 124 MW would serve to drive down the levelized cost of energy (LCoE), through learning, from its current level of around 240 £/MWh to below 150 £/MWh, based on a mid-range technology learning rate of 17%. Doing so would make tidal stream cost competitive with technologies such as combined cycle gas turbines, biomass and anaerobic digestion. Installing this 124 MW by 2031 would put tidal stream on a trajectory to install the estimated 11.5 GW needed to generate 34 TWh/year by 2050. The cyclic, predictable nature of tidal stream power shows potential to provide additional, whole-system cost benefits. These include reductions in balancing expenditure that are not considered in conventional LCoE estimates. The practical resource is also dependent on environmental constraints. To date, no collisions between animals and turbines have been detected, and only small changes in habitat have been measured. The impacts of large arrays on stratification and predator–prey interaction are projected to be an order of magnitude less than those from climate change, highlighting opportunities for risk retirement. Ongoing field measurements will be important as arrays scale up, given the uncertainty in some environmental and ecological impact models. Based on the findings presented in this review, we recommend that an updated national-scale practical resource study is undertaken that implements high-fidelity, site-specific modelling, with improved model validation from the wide range of field measurements that are now available from the major sites. Quantifying the sensitivity of the practical resource to constraints will be important to establish opportunities for constraint retirement. Quantification of whole-system benefits is necessary to fully understand the value of tidal stream in the energy system. Publisher PDF

The 2019/2020 Australian bushfires (or wildfires) burned the largest forested area in Australia's recorded history, with major socio-economic and environmental consequences. Among the largest fires was the 280 000 ha Green Wattle Creek Fire, which burned large forested areas of the Warragamba catchment. This protected catchment provides critical ecosystem services for Lake Burragorang, one of Australia's largest urban supply reservoirs delivering ~85% of the water used in Greater Sydney. Water New South Wales (WaterNSW) is the utility responsible for managing water quality in Lake Burragorang. Its postfire risk assessment, done in collaboration with researchers in Australia, the UK, and United States, involved (i) identifying pyrogenic contaminants in ash and soil; (ii) quantifying ash loads and contaminant concentrations across the burned area; and (iii) estimating the probability and quantity of soil, ash, and associated contaminant entrainment for different rainfall scenarios. The work included refining the capabilities of the new WEPPcloud-WATAR-AU model (Water Erosion Prediction Project cloud-Wildfire Ash Transport And Risk-Australia) for predicting sediment, ash, and contaminant transport, aided by outcomes from previous collaborative postfire research in the catchment. Approximately two weeks after the Green Wattle Creek Fire was contained, an extreme rainfall event (~276 mm in 72 h) caused extensive ash and sediment delivery into the reservoir. The risk assessment informed on-ground monitoring and operational mitigation measures (deployment of debris-catching booms and adjustment of the water supply system configuration), ensuring the continuity of safe water supply to Sydney. WEPPcloud-WATAR-AU outputs can prioritize recovery interventions for managing water quality risks by quantifying contaminants on the hillslopes, anticipating water contamination risk, and identifying areas with high susceptibility to ash and sediment transport. This collaborative interaction among scientists and water managers, aimed also at refining model capabilities and outputs to meet managers' needs, exemplifies the successful outcomes that can be achieved at the interface of industry and science. Integr Environ Assess Manag 2021;17:1151–1161. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC)., During manuscript preparation J. Neris, C. Santin, R. Lew, and S.H. Doerr were supported by a Natural Environment Research Council grant (NE/R011125/1).

The evaluation of sediment quality is a relevant topic that involves the analysis of various parameters that are altered by natural or anthropogenic causes. Therefore, the Grey Clustering method provides an alternative to evaluate sediment quality. In the present study, the sediment quality of the Chontayacu river watershed was evaluated considering the results of the monitoring of twenty-three points carried out in the early evaluations by the Environmental Impact Evaluation Agency (OEFA by its Spanish acronym). These twenty-three points were separated into three blocks considering the monitoring points upstream of the Uchiza town center and the Chontayacu Alto and Chontayacu Bajo hydroelectric plants. Seven parameters were analyzed: As, Cd, Cr, Cu, Pb, Hg and Zn, which were compared with Canadian sediment quality standards for the protection of aquatic life. The results of the assessment showed that all points in the Chontayacu River were classified as having unlikely adverse biological effects from heavy metals. However, a quality ranking was established between the points of each block where it was found that points P3, P4 and P17 correspond to the lowest values for the high CH, low CH and CP Uchiza blocks respectively. Finally, the results obtained will provide integrated information for decision making by the competent authorities in Peru, as well as indicate the level of sediment contamination that should be taken into account for the proposal of hydroelectric projects that influence sediment transport and entrainment.

Refined assessments of the available tidal stream energy resource are required to optimize turbines design and guarantee successful implementations and operations of devices in the marine environment. Investigations primary focused on identifying areas with maximum current speeds. However, further information may be reached by exhibiting (i) resource temporal variability, (ii) superimposed effects of meteo-oceanographic conditions (including especially wind-generated surface-gravity waves), and (iii) potential environmental impacts of operating turbines at the regional (e.g., changes in sediment transport and surrounding seabed features, effects on marine water quality, etc.) and local (wake-wake interactions and energy output) scales. These aspects are here investigated by reviewing a series of research studies dedicated to the Fromveur Strait off western Brittany, a region with strong potential for tidal array development along the coast of France. Particular attention is dedicated to the exploitation of combined in-situ and remote-sensing observations and numerical simulations. Beyond a site specific characterization of the tidal stream energy resource, this review promotes a series of original approaches and analysis methods for turbines optimization, thus complementing technical specifications to secure the key steps of a tidal energy project and promote the growth of a reliable tidal stream energy exploitation.

The development of tidal energy in Australia is still a challenge with few studies performed on the characterisation of the resource, due to the difficulty to acquire data and uncertainties about the influence of this anthropogenic activity on the marine environment. Changes in flow could lead to alterations in sediment transport and have further influence on the marine habitat. A case study in a promising area, Banks Strait (Australia), was created using high resolution 2D and 3D models validated against in situ data to investigate changes to hydrodynamic conditions with two scenarios of tidal farms (100 and 300 turbines). Comparison between 2D and 3D is performed to find the best compromise between model accuracy and computational time for preliminary assessment. Changes to current speed and bed shear stress over a 35 day period were found to be localised around the tidal farms and did not extent more than 7 km from the farm (300 turbines) for both 2D and 3D. The results showed that for near field and far field, 2D models are sufficient to give a first approximation of the hydrodynamic influence of tidal farm deployment on its environment.

The presence and magnitude of sediment contamination remaining in a completed dredge area can often dictate the success of an environmental dredging project. The need to better understand and manage this remaining contamination, referred to as "postdredging residuals," has increasingly been recognized by practitioners and investigators. Based on recent dredging projects with robust characterization programs, it is now understood that the residual contamination layer in the postdredging sediment comprises a mixture of contaminated sediments that originate from throughout the dredge cut. This mixture of contaminated sediments initially exhibits fluid mud properties that can contribute to sediment transport and contamination risk outside of the dredge area. This article reviews robust dredging residual evaluations recently performed in the United States and Canada, including the Hudson River, Lower Fox River, Ashtabula River, and Esquimalt Harbour, along with other projects. These data better inform the understanding of residuals generation, leading to improved models of dredging residual formation to inform remedy evaluation, selection, design, and implementation. Data from these projects confirm that the magnitude of dredging residuals is largely determined by site conditions, primarily in situ sediment fluidity or liquidity as measured by dry bulk density. While the generation of dredging residuals cannot be avoided, residuals can be successfully and efficiently managed through careful development and implementation of site-specific management plans. Integr Environ Assess Manag 2018;14:335-343. © 2018 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Hydrodynamics and sediment transport are key physical processes contributing to habitat structure within the marine environment. Coastal development that results in the alteration of these processes (e.g., changing water flushing and/or sedimentation rates) can have detrimental impacts on sensitive systems. This is a current relevant issue in Qatar as its coastal regions continue to be developed, not only around the capital of Doha, but in many areas around this Arabian Gulf peninsula. The Northeastern Qatari coast is comprised of diverse and sensitive flora and fauna such as seagrass and macro-algae meadows, coral reefs/patches, turtles and dugongs that tolerate harsh environmental conditions. In the near future, this area may see a rise in anthropogenic activity in the form of coastal development projects. These will add to existing natural stresses, such as high temperature, high salinity and low rates of precipitation. Consequently, there is a need to characterize this area and assess the potential impacts that these anthropogenic activities may have on the region. In this study, a novel sediment transport model is described and used to demonstrate the potential impact of altering hydrodynamics and subsequent sediment transport along the northeastern Qatar near shore marine environment. The developed models will be tested using potential scenarios of future anthropogenic activities forecasted to take place in the area. The results will show the effects on water and sediment behavior, and provide a scientificapproach for key stakeholders to make decisions with respect to the management of the considered coastal zone. Furthermore, it provides a tool / framework that can be utilized in environmental impact assessment and associated hydrodynamic studies along other areas of the Qatari coastal zone. This article is protected by copyright. All rights reserved

The environmental impact of the Three Gorges Dam has been a subject of vigorous academic, political and social debate since its inception. This includes the key issue of post-dam river channel erosion, which was predicted by the feasibility study to extend to the river mouth. In this paper we examine the geomorphic response of the channel of the middle Yangtze for 660 km downstream of the dam. Using data on channel characteristics, bed material and sediment transport, we show that in the decade following the dam closure, pre-dam seasonal erosion has been replaced by year-round erosion, a pattern most marked at the upstream end of the study area. The sediment carrying capacity of the river channel has been largely reduced below the dam. The locus of bed scour has moved progressively downstream, ceasing as the bed material became too coarse to be transported (e.g. D50: 0.29 mm pre-dam coarsened to 20 mm below the dam by 2008). About 400 km below the dam there is a reduction in channel slope that changes the sediment carrying capacity from 0.25 kg m−3 to only about 0.05 kg m−3, which is insufficient to move bed sediment. The new long-term hydro-morphological equilibrium that will be established in this section of the middle Yangtze will prevent the further incision downstream initiated by the Three Gorges Dam. The results suggest that the full extent of adverse environmental impact predicted by the pre-dam studies will not eventuate.

Effective management of marine environments requires a sound understanding of the relevant physical sedimentary sciences. Environmental impact assessment (EIA) is a key management and decision-making tool employed in Australia for coastal and marine developments. This article examines the veracity of the application of the marine physical sciences within the EIA process, using turbidity measurement and sediment transport pathways as examples. A review of EIA guidance reveals deficiencies in regulation. Turbidity measurement is poorly understood and performed in current practice, while a focus on protecting marine habitats largely ignores those physical sedimentary processes, such as long-term bed-sediment transport pathways, that create and maintain these habitats. Thus evaluations of impacts of offshore activities such as channel dredging and spoil emplacement at sea are fundamentally flawed. An extensive body of scientific knowledge is already available on marine physical processes, and equivale...

The presence of anthropic activity in the coastal or riverine environment modifies the wave as well as the water and sediment current regime. In particular, the body of water around ports is an area where intense currents and sediment transport rates are usually present and can be affected by low water velocities that take place close to the entrance and inside the port basin. Consequently, sediment can be entrained and accumulated in such areas, creating problems to navigation. Ports and moorings are filled with fine sediments due to deposition resulting from solid transport. In particular, silt particles settle because of the weak vertical and lateral shearing of the velocity field. The result is that harbours frequently require ordinary maintenance dredging. The dredging process involves the removal of sediment in its natural deposited condition by using either mechanical or hydraulic equipment. Dredging is a consolidated and proven technology, but involves considerable drawbacks. In particular, dredging has a notable environmental impact on marine flora and fauna, contributes to the mobility and diffusion of contaminants and pollutants already present in the silted sediments, obstructs navigation and is characterized by relatively high and low predictable costs. This paper aims to provide an original structured overview of technologies alternative to dredging that have been tested in the past 50 years. More than 150 articles have been analysed to compare standard dredging technologies with market-ready competitors from techno-economic and environmental perspectives. In particular, the paper focuses on anti-sedimentation infrastructures and on innovative plant solutions characterized by low maintenance costs and by a very limited environmental impact. The final aim of the paper is to describe the currently available technologies that prevent port inlet and channel siltation and to classify them through a techno-economic and environmental impact assessment. The comparison shows that dredging has both the higher costs and environmental impact, while fixed sand by-passing plants are characterized by the lowest environmental impact and operation costs that are competitive with dredging.

Wave energy converter (WEC) arrays deployed in coastal regions may create physical disturbances, potentially resulting in environmental stresses. Presently, limited information is available on the nature of these physical disturbance or the resultant effects. A quantitative Spatial Environmental Assessment Tool (SEAT) for evaluating the potential effects of wave energy converter (WEC) arrays on nearshore hydrodynamics and sediment transport is presented for the central Oregon coast (USA) through coupled numerical model simulations of an array of WECs. Derived climatological wave conditions were used as inputs to the model to allow for the calculation of risk metrics associated with various hydrodynamic and sediment transport variables such as maximum shear stress, bottom velocity, and change in bed elevation. The risk maps provided simple, quantitative, and spatially-resolved means of evaluating physical changes in the vicinity of a hypothetical WEC array in response to varying wave conditions. The near-field risk of sediment mobility was determined to be moderate in the lee of the densely spaced array, where the potential for increased sediment deposition could result in benthic habitat alteration. Modifications to the nearshore sediment deposition and erosion patterns were observed near headlands and topographic features, which could have implications for littoral sediment transport. The results illustrate the benefits of a risk evaluation tool for facilitating coastal resource management at early market marine renewable energy sites.

The purpose of the study is to reveal changes of the hydrodynamics and sediment transport induced into the river channel by the operation of small hydropower plants (SHPs). A 36-km reach of...

The modern climate trend and population growth have dramatically increased the need for maximization of the net benefit from the existing storage space in freshwater reservoirs. However, sedimentation in reservoirs through physical deposition and/or slope failures is a major threat to their productivity and life expectancy. In this context, the sedimentation impact on the sustainability of Mornos Lake/Reservoir, which is exceptionally vital for the ~ 3.1 million inhabitants of Athens, had to be evaluated. Therefore, a meticulous geophysical survey of the reservoir bed was conducted in 2015 for the very first time. Bathymetric, sidescan sonar, and seismic profiling datasets, all integrated with real-time kinematic (RTK) positioning, were analyzed for a realistic evaluation of the storage capacity loss. Approximately 18.2 × 106 m3 of lacustrine sediments derived through physical wedge-type deposition process and ~ 800,000 m3 of material produced by slope failures have covered the bottom since reservoir commissioning in 1981. This configures an average storage capacity loss of ~ 0.07% per year, which, however, is one of the lowest rates worldwide. Moreover, the 108-m-deep reservoir basin can presently accommodate a maximum active water volume of ~ 740 × 106 m3. The siltation pattern and sediment transport pathways in the reservoir are principally controlled by vigorous turbidity underflows, which deliver sediment mainly to the dam area (deposition thickness up to ~ 7 m) as well as to the pumping area (deposition thickness up to ~ 4 m) posing there a future risk; nevertheless, according to the predicted lake bathymetry, this risk will be negligible till 2045.

This paper describes a model of the sediment transport processes inside the hopper of a trailer suction hopper dredger. The model is part of the TASS system – a software program that enables the user to predict the spatial development and concentration of turbidity plumes arising from dredging activities by trailer suction hopper dredgers. TASS has been developed because of a recognised need by the dredging industry to improve the quality of predictions of the effects of dredging in environmental impact assessments. This paper describes the hopper process model and the validation of overflow predictions against validation measurements off the Dutch, German and Australian coasts. The model is shown to perform well in quantitative comparisons with data for dredging silt and sand in the Netherlands and Germany. A more qualitative comparison in Australia (owing to uncertainty in the nature of the soil being dredged) also indicates the hopper process model predicts the correct range of sediment discharge.

In the last decade, the number of offshore wind farms has increased rapidly. Offshore wind farms are typically constructed in near-shore, shallow waters. These waters can be highly productive or provide nursery grounds for fish. EU legislation requires assessment of the environmental impact of the wind farms. The effects on hard and soft substrate fauna, seabirds and marine mammals are most frequently considered. Here we present Landsat-8 imagery that reveals the impact of offshore wind farms on suspended sediments. Turbid wakes of individual turbines are observed that are aligned with tidal currents. They are 30–150 m wide, and several km in length. The environmental impact of these wakes and the source of the suspended material are still unclear, but the wake size warrants further study. The underwater light field will be affected by increased suspended sediments and the turbid wakes could significantly impact sediment transport and downstream sedimentation. The question of whether such features can be detected by other remote sensors is addressed by a theoretical analysis of the signal:noise specification for the Operational Land Imager (OLI), the Enhanced Thematic Mapper Plus (ETM +), the Advanced Very High Resolution Radiometer (AVHRR/3), the Moderate-Resolution Imaging Spectroradiometer (MODIS), the Spinning Enhanced Visible and Infrared Imager (SEVIRI), the Flexible Combined Imager (FCI) and the Multispectral Instrument (MSI) and by a demonstration of the impact of processing OLI data for different spatial resolutions.

In recent years, laws ands regulations in the field of ecology became more strict due to public pressure. Therefore, the discharge of fines during dredging and land reclamation works and its impact on seafloor habitats is an important aspect in environmental impact assessments. We describe an approach in which an underwater gamma spectrometer can be used to quantitatively map the concentration of fines in sediments. With this approach, the natural variation of fines and thereby the buffering capacity of the seafloor can be monitored and the natural dynamics due to re-suspension and large-scale sediment transport patterns can be quantified. The information derived from the geophysical measurements give the opportunity to measure the effects of human induced projects at sea.

This paper suggested the improvement of marine environmental impact assessment in eastern coast as analyzing consultation on the coastal area utilization for development of ports and fishing harbors for 3years in the east coast. The results of survey are only 3cases, 12cases and 16cases each for ocean currents, wave and sounding data. However, for development of ports and fishing harbors in eastern coast, ocean characteristics in eastern coast different than in the West Sea, South Sea is considered to marine environmental impact assessment. For development of ports and fishing harbors in east coast where the influences of ocean currents, wind-driven current and waves are dominant, the effect of the current should be considered to improve the reproducibility of tidal current. The wave should also be considered as an assessment criteria to obtain the validity of project such as harbor tranquility, functionality of breakwaters and stability. In addition, sediment inflow in river and exact water depth data of the ocean should be applied to numerical modeling and set wave-induced current to external force of sediment transport to predict the problems such as the harbor siltation and the coastal erosion considering ocean characteristics in the east coast.

The environmental impact assessment (EIA) of cascade dams building in international rivers has been widely discussed in China and ASEAN countries since the 1990s. In Southwest China, all the great mountainous rivers have been the major state base for large-scale hydropower development. Among these rivers, the environmental change and response of the watercourse under the cascade dams building in the upper Mekong (called Lancang River in China) has been the focus in recent 20 years. In this paper, the Lancang River, which has over 25 years of large-scale hydropower development, was chosen as a case study for establishing the affected evaluation indicators system and its regression model of runoff and sediment, determining the indicators weight by the hierarchy analysis method and factor analysis method, and setting up the quantitative evaluation models of indicators affected level based on the “marginal efficiency” principle. Using these methods and model established, the influence degree of runoff and sediment in the Lancang River from 1986 to 2007 were assessed. The major results are: (1) the impact of sediment transport change by the cascade development is much higher than that of the runoff change; (2) the years’ number with different impact levels respectively are 72.7% as the “smallest” level, 18.2% as “smaller”, and 9.1% as “general”; (3) the change process of runoff and sediment shows a “U-shaped” pattern, which indicates the balance of sediment change because of the interaction of sediment reduction by Manwan reservoir storage and the increase by the Dachaoshan dam construction.

The introduction of a large infrastructure of marine energy technology along coastal environments raises some concern on how this will impact on the marine environment. While there are a number of potential environmental impacts of wave energy devices (eg, collision) the focus of this chapter is on the primary ecological processes that may be influenced by changes in the hydrodynamics as a direct result of the installation of wave energy converters (WECs). These processes include sediment transport, organism transport, pollution, and biogeochemical processes. While full-scale wave energy farms are still in the development phase, the most effective way to predict the environmental impacts of large infrastructure in the coastal marine environment is by coupling ecological with hydrodynamic modelling. This chapter therefore is designed to provide guidance on what factors should be considered when developing a coupled hydrodynamic-ecological model when modelling WEC arrays.

In response to increasing concerns about the potential toxicological impacts of (extreme) flood events, scientists from several disciplines have joined to form the interdisciplinary research project named FLOODSEARCH. FLOODSEARCH is one of the recent Pathfinder Projects supported by the German Excellence Initiative via the Exploratory Research Space at RWTH Aachen (ERS). FLOODSEARCH aims to combine methodologies of hydraulic engineering and ecotoxicology in a new interdisciplinary approach to assess the risks associated with the re-mobilisation of particulate bound contaminants often observed after severe flood events. Impacts of extreme flood events and aspects of re-mobilisation of sediment-bound toxic compounds will be characterised and evaluated in controlled experiments fusing flood simulation technologies with biological effects assessment. The overall goal is to establish a novel and more realistic approach towards flood event testing that can be applied to a number of different questions and species. Specifically, model aquatic species such as rainbow trout (Onchorhynchus mykiss) will be exposed to particle-bound contaminants in flood-like conditions in a specifically designed annular flume that permits monitoring of both physical/chemical and biological parameter. Ultimately, this approach will assist to further our understanding of the potential biological risks associated with increasingly frequent extreme flood events, e.g., as a consequence of climate change, by bridging the gap between the physical (re-)mobilisation of contaminants and resulting toxicological impacts on aquatic organisms. Thus, it is the objective of the project to derive relationships between the hydrodynamic parameters such as velocities and turbulences, the parameters associated to sediment transport such as sediment concentration and grain sizes and the biological parameters.

To clarify the deposition process in a riverine-type mangrove area which is directly influenced by terrestrial water with rich nutrients and high suspended-sediment concentration (SSC), we have conducted field measurements on suspended-sediment transport and deposition process in the Miyara River, Ishigaki Island, Okinawa, which has a typical riverine-type mangrove forest. The observed SSCs in the swamp are relatively lower than those in the creek under hydrologic events. The observed results reveal that the accretion rates of ground level are 3.1 and 1.3 cm/year in the upstream and downstream regions of the swamp, respectively. These facts demonstrate that the deposition rate of sediments are dominant in the upstream regions due to the huge environmental impact from inland and the mangrove swamp may capture a large amount of suspended sediments.

The monitoring of existing coastal protection work and comparing the actual performance with the predicted one is one of the methods for developing coastal engineering processes. A comprehensible example, which clearly demonstrates the value of this monitoring process, could be found in the coastal protection works of El Agami resort area, Egypt. A group of seven detached breakwaters were constructed in front of the study area aiming to improve the beach condition with consideration for swimming capability. This is in addition to a temporary harbor to facilitate execution of the breakwaters. Deposition of seagrass and an undesirable temporary harbor are part of the coastal area problems. The implicit sediment transport two-dimension (ImSedTran-2D) numerical model, prototype data during the period from October 2002 to October 2003, and the empirical design relationships were used to study the environmental impact assessment of the breakwaters. Accordingly, a decision was made to eliminate the temp...

Low-head structures are widely used in river restoration. Their function is to regulate the sediment transport and at the same time they can assure optimal habitat for fish species in the river. They strongly affect river morphology because of the erosive processes occurring downstream of them. Thus, a correct design has to take into account several aspects, i.e. technical, economic, environmental, etc. The present chapter aims to present the most recent achievements in scientific literature regarding the design criteria for low-head structures. In particular, low-environmental impact structures will be analyzed and illustrated. In the last decades, the environmental sensibility has increasingly forced hydraulic engineers to propose design solutions which can conjugate both hydraulic functioning and environmental impact minimization. This chapter proposes a synthesis of criteria to predict scour characteristics of the stilling basin downstream of several low-head structure typologies. Namely, the scour process downstream of block ramps will be discussed and the effect of both stilling basin geometry and ramp configuration will be analyzed, for both clear water and live bed conditions. Furthermore, the erosive process downstream of rock grade control structures and stepped gabion weirs will be illustrated along with relationships to predict the characteristic lengths of the scour hole and dune.

In regions where multiple marine dredging activities take place in a spatially restricted area, cumulative effects may impact sensitive receptors, both locally and regionally. In the UK, marine dredging of sand and gravel generally occurs in spatially limited regional blocks, with approximately 20 million tonnes of resource dredged each year from English and Welsh waters.

Increasing energy demands and concerns about global warming call for an increase in energy generation from renewable sources. Small hydropower plants represent a significant contribution to meet this demand. But the optimal use of this resource in a sustainable manner still remains a challenge. A cascade of small dams may have detrimental impacts on the environment and water use without implementation of proper mitigation measures and planning. To obtain more insight in the consequences of hydropower cascades and possibilities to improve the cascade planning process in order to reduce such impacts, the Vietnamese Ministry of Industry and Trade and the World Bank jointly initiated the study on cumulative impacts and joint operation of small-scale hydropower cascades Supported by the Renewable Energy Development Program (REDP) in Vietnam. Chapter two provides a brief background on the small-scale hydropower development in Vietnam including its current planning procedures, while Chapter three provides a description of the six studied river basins. Chapter four describes the approach, methods and definitions of the study. During the first phase of the study all six rivers were screened for potential significant cumulative impacts. The results of this screening were presented in a separate report, of which the summary is given in chapter five. This screening showed that for four of the rivers significant cumulative impacts can be expected, which merited further detailed analysis. These four rivers are Ngoi Xan, Nam Tha, Nam Chien and Sap. For each of the four detailed study cases a description of the river basin and hydropower cascade has been made, the hydrological and environmental impacts were assessed and opportunities for joint operations quantified. This report presents summaries of the cumulative impact analyses (chapter six) and draws general conclusions with respect to present and future environmental conditions (chapter seven). It also summarizes the results of the optimization modeling for each cascade (chapter eight) and provides recommendations for future planning and cascade operation (chapter nine).

This paper presents a case study where numerical modelling was utilized for the first time to estimate shoreline changes during the planning of a private pleasure marina in the Gulf of Suez. The study was made to compliment an environmental impact assessment study (EIA) requested by the Egyptian Environmental Affairs Agency (EEAA). The paper presents data collected during two surveys and the results of the numerical model. The impact of the marina on the sediment budget was investigated using the GENESIS one-line program. One of the main reasons for the study was to confirm that the choice of the marina location ensured minimum erosion of the shoreline. In the model, the sediment transport calibration constants were determined using the results of two surveys. The choice of the formula is discussed in the paper. Two locations for the marina were tested against minimum erosion at the down drift side of the marina. This study was performed in close co-ordination with the EEAA and several solutions were suggested to minimize the expected accretion before the final location was approved.

A synthesis of environmental data compiled over the past 25 years is reviewed and organized. We describe the anticipated activities associated with exploration for commercial deposits, with engineering tests of recovery and mining systems, and with basic metallurgical processing. Basic description of the manganese nodule oceanographic environment is presented, including the occurrence of nodule deposits, relative sediment properties, benthic currents, and biological community. Environmental impacts from previous studies are summarized. Studies to date support the original concerns for environmental impact identified in the DOMES research, including impact on the benthic community where nodules are removed; impacts of the discharged plume on the near-surface biota; and impacts on the benthos due to deposition of suspended sediment. Future studies should address the establishment of quantitative relationships between resedimented thickness and benthic community response; integration of mining-related resear...

As the safe depth for navigation is no longer ensured due to intense accumulation of sediments in the avanport of the old port, which was constructed in 1923–1940, reconstruction of Šventoji port jetties was planned, which should commence in 2013. The assessment of impact of Šventoji port jetties was done on the nearby coasts, based on analysis of the 20th and 21st century cartographic material as well as monitoring data on coastal dynamics. The old port construction caused the formation of the accumulative cape; the area of which has grown to 44.90 ha. The coastline erosion processes have become especially intense northwards from the formed cape to the Latvian border. Approx. 38.41 ha area of land has been washed-out in the section. During the last 17 years, the southern jetty has become more and more pervious to sediments. Sediment volume stabilization occurred on the northern side of the jetty, and accumulation tendency was in the southern part of the port. Results of sediment transport modelling with MIKE 21 confirm that the reconstruction of Šventoji port according to alternative “1” (length of jetties – 400 m) answers the minimal requirements of port and makes the least impact for the hydrodynamic and lithodynamic processes in the Baltic Sea nearshore. The reconstruction of port according to alternative “2” (length of jetties – 800 m) will cause the intensive changes of the Baltic Sea coastline dynamics in adjacent regions. First published online: 14 Dec2012

The coastal regions of the Mediterranean are the site of countless economic and recreational activities, but are threatened by dramatic dangers of misuse and pollution. Adequate tools are needed to study the environmental pressure imposed on these regions by the conflicting needs of protecting their ecological balance and exploiting their natural resources. Coastal ecosystems are very sensitive to the environmental impact of land use in watersheds, along the coast and further inland, of fluvial discharges, and of marine processes. Weathering, erosion, or waste disposal on land, as well as other activities at sea, such as shipping, dumping or oil extraction, are but a few of the factors which would require that the coastal areas be suitably monitored. Modern techniques of environmental assessment call for the use of integrated observation systems. The collection of data with traditional coastal installations remains an important component of such research. However, the large space scales and short time scales of many near-coastal and/or marine processes require the use of (orbital) remote sensors. In particular, optical sensors, operating in the visible/infrared spectral region, have shown their usefulness for providing novel information on physical, geo-chemical and biological processes of the coastal area. Optical remote sensing of the coastal zone finds applications in studies of land use, surface cover, hydrology and coastal ecology at large; of water quality and sediment transport, coastal runoff and circulation, or dynamical processes (looking, e.g., at the evolution of pigment and/or temperature patterns, and their distribution as related to plankton dynamics, currents or river plumes); as well as in those of energy transfer, carbon cycling and climatology in general. Selected applications of optical observation techniques in the Mediterranean region, conducted in the framework of international demonstration programmes (i.e. the Ocean Colour European Archive Network, OCEAN, Project), provide examples of the remote sensing potential in the field of integrated coastal/marine environmental management.

The Islands of MarthaAƒÂ¢A‚€A‚™s Vineyard and Nantucket are separated from the Massachusetts mainland by Vineyard and Nantucket Sounds; water between the two islands flows through Muskeget Channel. The towns of Edgartown (on MarthaAƒÂ¢A‚€A‚™s Vineyard) and Nantucket recognize that they are vulnerable to power supply interruptions due to their position at the end of the power grid, and due to sea level rise and other consequences of climate change. The tidal energy flowing through Muskeget Channel has been identified by the Electric Power Research Institute as the strongest tidal resource in Massachusetts waters. The Town of Edgartown proposes to develop an initial 5 MW (nameplate) tidal energy project in Muskeget Channel. The project will consist of 14 tidal turbines with 13 providing electricity to Edgartown and one operated by the University of Massachusetts at Dartmouth for research and development. Each turbine will be 90 feet long and 50 feet high. The electricity will be brought to shore by a submarine cable buried 8 feet below the seabed surface which will landfall in Edgartown either on Chappaquiddack or at Katama. Muskeget Channel is located between MarthaAƒÂ¢A‚€A‚™s Vineyard and Nantucket. Its depth ranges between 40 and 160 feet in the deepest portion. Itmore » has strong currents where water is transferred between Nantucket Sound and the Atlantic Ocean continental shelf to the south. This makes it a treacherous passage for navigation. Current users of the channel are commercial and recreational fishing, and cruising boats. The US Coast Guard has indicated that the largest vessel passing through the channel is a commercial scallop dragger with a draft of about 10 feet. The tidal resource in the channel has been measured by the University of Massachusetts-Dartmouth and the peak velocity flow is approximately 5 knots. The technology proposed is the helical Gorlov-type turbine positioned with a horizontal axis that is positively buoyant in the water column and held down by anchors. This is the same technology proposed by Ocean Renewable Power Company in the Western Passage and Cobscook Bay near Eastport Maine. The blades rotate in two directions capturing the tides energy both during flood and ebb tides. The turbines will be anchored to the bottom and suspended in the water column. Initial depth of the turbines is expected to be about 25 feet below the surface to avoid impacting navigation while also capturing the strongest currents. The Town of Edgartown was initially granted a Preliminary Permit by the Federal Energy Regulatory Commission (FERC) on March 1, 2008, and has recently received a second permit valid through August 2014. The Preliminary Permit gives Edgartown the exclusive right to apply for a power generation license for power generated from the hydrokinetic energy in the water flowing in this area. Edgartown filed a Draft Pilot License Application with FERC on February 1, 2010 and an Expanded Environmental Notification Form with the Massachusetts Environmental Policy Act (MEPA) Office at the same time. It expects to file a Final License Application in late 2013. Harris Miller Miller & Hanson (HMMH) of Burlington Massachusetts is acting as the Project Manager for the Town of Edgartown and collaborating with other partners of the project including the University of Massachusetts - Dartmouth's Marine Renewable Energy Center and the Massachusetts Clean Energy Center. HMMH was awarded a grant under the Department of Energy's Advanced Water Program to conduct marine science and hydrokinetic site-specific environmental studies for projects actively seeking a FERC License. HMMH, on behalf of the Town, is managing this comprehensive study of the marine environment in Muskeget Channel and potential impacts of the tidal project on indicator species and habitats. The University of Massachusetts School of Marine Science and Technology (SMAST) conducted oceanographic studies of tidal currents, tide level, benthic habitat, and potential for biofouling and foundation scouring. Woods Hole Oceanographic Institution, cooperating with SMAST, developed an oceanographic model to predict changes in sediment transport as a result of the proposed tidal energy project. Provincetown Center for Coastal Studies prepared background material on protected species - including whales, seals, and sea turtles - in the project area and implemented an initial tagging program to record location specific information on seals and sea turtles. HMMH communicated research plans and findings with local stakeholder groups, state and federal resource agency staff, and the ocean power industry. The information is being used to prepare environmental permit applications and obtain approvals for project construction.« less

In support of the environmental assessment and regulatory approval process and as an interim guidance for field work, a number of numerical modeling studies of the sediment disposals were recently carried out by ASL Environmental Sciences Inc. at the designated/potential disposal sites in inshore waterways of British Columbia, Canada, using the 3D numerical model COCIRM-SED and the short-term fate model of sediment disposal STFATE. In these applications, STFATE was used to provide initial distributions of suspended sediment and bottom accumulation in details, typically within the first hour of the sediment disposal operation, as a useful interim guidance for field work and input to the 3D model COCIRM-SED, which was then adapted to examine the transport and fate of all disposal materials over much larger spatial scales and longer periods of time. This paper reports the model approaches and the detailed model results in the Brown Passage application. Introduction Dredged marine sediment and excavated terrestrial overburden from coastal engineering projects are commonly disposed at designated sites in ocean and coastal open waters via release from barges or pipelines. However, the sediment disposal in these areas can have adverse environmental impacts, especially on marine life and fish habitats, in the form of bottom accumulation and increasing total suspended sediment (TSS) levels in the water column (Fissel and Jiang, 2011). Thus, the shortterm (with durations of hours to about a day) and long-term (with durations of days to months) transport and fate of the disposal sediment during and after the disposal operations are of particular concern to coastal engineers and environmental scientists in assessing potential environmental effects and obtaining regulatory approval. The progress realized in advanced circulation and sediment transport numerical models provides useful and reliable tools in quantitatively predicting transport and fate of disposal sediment. Recently in ASL Environmental Sciences Inc., numerical modeling studies of the short-term and long-term transport and fate of the disposal sediment were successfully carried out at a number of designated/potential sediment disposal sites in the inshore waterways of British Columbia, Canada (Figure 1). These studies used the ASL’s own 3D COastal CIRculation and SEDiment transport Model (COCIRM-SED) and the Short-term FATE model of sediment disposal (STFATE), developed by the U.S. Army Corps of Engineers. The model results were used to address the potential impacts of the sediment disposal on the natural environment of receiving ambient ASL Environmental Sciences Inc., #1 – 6703 Rajpur Place, Victoria, BC, V8M 1Z5, Canada, jjiang@aslenv.com and dfissel@aslenv.com 40 1A _5 12 20 _A S C E _T es t.j ob _P ro ce ss C ya n_ 08 /2 4/ 20 12 _0 6: 48 :3 4 40 1A _5 12 20 _A S C E _T es t.j ob _P ro ce ss M ag en ta _0 8/ 24 /2 01 2_ 06 :4 8: 34 40 1A _5 12 20 _A S C E _T es t.j ob _P ro ce ss Y el lo w _0 8/ 24 /2 01 2_ 06 :4 8: 34 40 1A _5 12 20 _A S C E _T es t.j ob _P ro ce ss B la ck _0 8/ 24 /2 01 2_ 06 :4 8: 34

Enclosed seas on a world scale are typically characterised by low tidal currents and flushing potential, yet are centres of high population and therefore pollution pressure. Accordingly it is appropriate that recognised environmental assessment procedures are applied. For those examples which have little co-ordinated data, a full baseline environmental investigation is needed to establish a data base against which to measure future change. An appropriate way to achieve this is using an integrated multi-disciplinary approach involving the following components: 1. 1.- review of previous work and collation of existing data. 2. 2.- bathymetric and geomorphologic evolution, and changes. 3. 3.- determination of bottom sediment facies and sediment transport pathways and budgets. 4. 4.- investigation of water column and surficial sediment geochemistry and ecotoxicity. 5. 5.- inlet hydraulics, tidal, current and wave climate measurements. 6. 6.- investigation of marine biology and ecology, and the patterns of eco-distribution in relation to the sedimentologic, oceanographic and pollution parameters. 7. 7.- numerical modelling of current hydrodynamics. 8. 8.- numerical modelling of water quality and pollution dispersion. 9. 9.- numerical modelling of hazards such as tsunamis, storm surge and flooding, and the effect of such events on the enclosed sea hydrodynamics, pollution and sediments. 10. 10.- review of the efficacy of the numerical models in relation to the field and empirical data; i.e. how well do the models fit perceived “reality”? Only by undertaking an integrated, multi-disciplinary study can the best planning decisions be made for future resource utilisation and management of the enclosed seas. Presently such a study is proposed for Osaka Bay, Japan.

Uranium is generally associated with the gold ores of the Witwatersrand, at times at concentrations which may be economically viable for extraction as a by-product to the gold. Uranium and its radiogenic progeny are therefore found in many of the residues and wastes produced in the mining and processing of Witwatersrand ores. The airborne radiometric method is capable of detecting these wastes and the downstream concentrations of radioactive material deposited by sediment transport and chemical precipitation processes. Although the airborne method can provide full coverage of the area surveyed and is sensitive to small variations in surface radioactivity, its use as a quantitative environmental assessment tool is limited by a number of factors such as elevated natural background, secular equilibrium and disequilibrium, geometric factors and the lack of depth penetration of the method. Nevertheless the airborne radiometric method can be utilized in the investigation of a range of environmental problems related to mining in the Witwatersrand Goldfields and can play a valuable role as a screening tool in environmental risk assessments.

A chain of barrier islands in the Gulf of Mexico reduces storm and hurricane impacts along the Mississippi coast. Ship Island, one of the largest islands of this chain, was breached by hurricanes Camille and Katrina creating a 5.5 kilometer wide gap. US Army Corps of Engineers plans to restore the island nourishing 15 million cubic meters of sand. Extensive modeling studies were carried out to support the environmental impact assessment and to optimize design. The main objective of these studies was to determine the impact of the restored island on the environment. The possible increase of sedimentation rates in the adjacent navigation channel connecting a major port to the Gulf of Mexico was of particular interest. The Delft3D models, calibrated on measurements of waves, tidal levels and currents, were used to estimate the annual sediment transport rates. These models were subsequently applied to optimize the design of the closure of Camille Cut. The optimum construction sequence was established. Sediment losses from the fill, and the impact of turbidity plumes on the nearby sea grass fields were determined.

Integration of processes-based models is an effective approach to simulate complex multi-scale coastal processes in estuaries and coasts. In general, coastal process modeling aims at predicting irregular wave deformations, wave-induced currents, sediment transport, morphological processes, and/or other concerned physical processes like fresh water exchanges and ecological responses. Although modelers can validate individually each submodel related to a single process like wave, current, or sediment transport, it is still difficult to verify and validate highly integrated multi-process models, due to the interactions of submodels in the multiscale processes. In the paper, several numerical examples for validation of each process submodel in the integrated coastal process model are presented. The interactions of these submodels for modeling wave deformations, currents, and seabed changes, are also discussed. Moreover, a long-term simulation result about the seabed change of a coastal zone with installation of coastal structures is presented; and an application of the numerical model to select a plan of a groin in a harbor is demonstrated. The results indicate that this comprehensively validated coastal process model can insure the capabilities and reliabilities in the applications to the marine environmental impact assessment for coastal zone sediment management and coastal structure planning.

Dredging, by its very nature, causes an environmental impact. The relative scale of the impact is a function of many factors including the dredging operation, the hydrography of the area and the sensitivity of the site. During the last two decades, environmental impact was often measured by the immediate and long-term impact on flora and fauna at a species level, but regulators and environmentalists alike now feel that the optimum way of protecting single species is to sustain the health and balance of a habitat. Determination of environmental impact by measuring biological effects can be costly, long term and inconclusive leading to considerable debate between port management, regulators and environmentalists. If dredged sediment never actually reaches a sensitive site or is only deposited at levels well below natural ambient then long-term biological monitoring is at best likely to lead to further monitoring over a longer period and increased costs. It is proposed that significant cost-savings can be made and delays for port developments reduced if, initially, physical effects are monitored and understood and the data used to relate to biological impact or focus in on the specific needs for any biological monitoring that is required. The use of sediment tracers coupled with a standard suite of marine survey techniques provides tangible data on sediment transport rates and deposition in order to assess environmental impact.

Nearshore placement of sand is becoming a more popular option in two related types of coastal engineering projects: beach nourishment and inlet dredging. Placing the sand in the nearshore instead of directly on the beach can reduce the costs of a beach nourishment project (Douglass 1995); furthermore, the environmental impact to the beach and dune ecosystem may be perceived to be less for open-water disposal with subsequent migration than for direct placement on the beach. Nearshore placement of sand is also an option in navigation dredging projects for similar reasons. Several design and planning questions relate to the fate of dredged sand placed in the nearshore. Can we economically use profile nourishment, and what is the certainty that a constructed submerged feature will move onshore or remain in place? And if it will move, what is the rate of its movement? Another question concerns how deep material should be placed. In order to answer these questions, together with physical model experiments, several empirical/numerical models have been developed in the past in the United States as a part of the Corps of Engineers ‘Dredging Research Program’ (DRP) (Hands 1991, Larson and Kraus 1992). Hydrodynamic modelling of the nearshore environment has reached a verifiable level of maturity in the last decades as a result of well-defined equations, established numerical solutions and quality laboratory and field data. On the contrary, modelling of sediment transport and beach profile evolution has not yet approached a similar level of accuracy. Most commonly applied models to predict beach profile modifications and to estimate the migration rate of nearshore constructed sand mounds rely on empirical relationships (Douglass 1995). More recently, the numerical model C-SHORE (Kobayashi et al. 2007; Figlus et al. 2011) was developed resulting in simple, practical and accurate code that predicts beach–dune profile evolution over the near-shore region in response to waves, currents and water levels. In the present work, a calibration and verification procedure is considered for the numerical model C-SHORE (Kobayashi et al. 2007) and the empirical model (Douglass 1995).

This report presents and documents preliminary findings of an information review performed to develop environmental guidance for flood-control projects that involve modification of natural stream channels by clearing and snagging, alignment, enlargement, and lining. The response of the fluvial system to modification sometimes results in unintentional or unforeseen environmental impacts. In general, channel modification results in a shorter, smoother, more uniform channel with larger cross-sectional area and less natural vegetation. Overbank flooding is eliminated or reduced, and depths and velocities are changed at all flows. Since extreme channel instability has adverse effects on ecological and aesthetic resources, channel straightening should be minimized. The channel cross section should be designed for low as well as high flows; the existing velocity-versus-discharge relationship should be preserved as much as possible at low an intermediate flows to maintain the sediment transport characteristics of the existing channel. Environmental features have been found to have limited effectiveness unless the modified channel is reasonably stable, the project area is protected against further modification, and construction and maintenance work is closely supervised and inspected.

Progress during the first 18 months in implementation of the Unified Transport Approach (UTA) is summarized in this report, which covers the period through December 1976. The goal of this project is to develop mathematical models for fast-transient, one-and two-dimensional transport of thermal, radiological, chemical, and biological properties in rivers, estuaries, lakes, and coastal regions for assessing the impact of power-plant operations. Development and validation of these models are illustrated in applications at several sites where data is available. The models include submodels for sediment transport, exchange of a soluble isotope with sediment, and zone-matching models to connect near-field problems of reentrainment and recirculation with far-field convective transport. Several types of automated data preparation have been introduced, and the codes have been designed to allow input of specified plant operating conditions for given durations. The UTA provides a common basis for calculating the transport of intensive quantities that depend on basic flow properties, which can be obtained from a common set of data for geometry, bathymetry, and meteorology that must be prepared only once. The formulation and calculation are based on a stable set of algorithms that have been tested and proven valid. The user can then focus on understandingmore » and interpreting thermal, chemical, or radiological transport results with confidence that the basic calculations are direct, efficient, and meaningful. Recent work in each of the three areas is described.« less