Submarine power cables (SPC) have been in use since the mid-19th century, but environmental concerns about them are much more recent. With the development of marine renewable energy technologies, it is vital to understand their potential impacts. The commissioning of SPC may temporarily or permanently impact the marine environment through habitat damage or loss, noise, chemical pollution, heat and electromagnetic field emissions, risk of entanglement, introduction of artificial substrates, and the creation of reserve effects. While growing numbers of scientific publications focus on impacts of the marine energy harnessing devices, data on impacts of associated power connections such as SPC are scarce and knowledge gaps persist. The present study (1) examines the different categories of potential ecological effects of SPC during installation, operation and decommissioning phases and hierarchizes these types of interactions according to their ecological relevance and existing scientific knowledge, (2) identifies the main knowledge gaps and needs for research, and (3) sets recommendations for better monitoring and mitigation of the most significant impacts. Overall, ecological impacts associated with SPC can be considered weak or moderate, although many uncertainties remain, particularly concerning electromagnetic effects.

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A review of potential impacts of submarine power cables on the marine environment: Knowledge gaps, recommendations and future directions

Assessment of circulation and inter-basin transport in the Salish Sea including Johnstone Strait and Discovery Islands pathways

A finite volume, ocean circulation model was applied to the Discovery Islands region of British Columbia and used to simulate the three-dimensional velocity, temperature and salinity fields required by a companion biological transport model. The circulation model was initialized with a combination of climatological data and recent temperature and salinity observations, and forced with i) winds measured at seventeen weather stations, ii) the discharges from twelve rivers, and iii) five tidal constituents. A simulation for the period 1 April to 28 April 2010 was evaluated using simultaneous observations from three current meter moorings and the harmonics computed from historical measurements at twenty-four tide gauges. Though the model tidal elevations were shown to be in excellent agreement with the observations, profiles of model tidal speed versus depth generally did not capture observed vertical variations as well. Mean and low-pass filtered flow fields, though reasonably accurate near the surface, were...

A Circulation Model for the Discovery Islands, British Columbia

https://portal.helcom.fi/meetings/HELCOM%20TAPAS%20Pressure%20Index%20WS%201-2016-329/Related%20Information/Reference%20report%201%20annex%202%20Hammar%20et%20al%20Ecological%20risks%20Kattegat%20cod%20Renewable%20Energy%2066%20414-424%202014%20Annex%20B.pdf

Assessing ecological risks of offshore wind power on Kattegat cod

Platform of integrated tools to support environmental studies and management of dredging activities.

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

https://www.aslenv.com/reports/NumMod-ECM-12-2011-2.pdf

Modeling Sediment Disposal in Inshore Waterways of British Columbia, Canada

A high resolution three-dimensional numerical model, COCIRM, was adapted and optimized to predict the potential impact of the Waneta Expansion Project (WEP) on the flow conditions at the confluence of the Columbia and Pend d’Oreille rivers. Flows in this confluence area represent important habitat features for white sturgeon, including the well-developed low-speed Waneta Eddy for sturgeon rearing and feeding, and the jet-like high-speed Pend d’Oreille River outflow for sturgeon spawning. Extensive model calibrations and validations were carried out to render the model a useful and reliable tool for the WEP environmental impact assessment. The model results are in good agreement with extensive in situ observations in terms of the patterns of the Waneta Eddy, Pend d’Oreille outflow and its associated standing waves as well as water temperatures.

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3D Numerical Modeling of Flows at the Confluence of the Columbia and Pend d'Oreille Rivers

A three dimensional, integrated numerical model, COCIRM-SED, was applied to predict the sediment plumes and deposition resulting from the removal and installation activities of existing and proposed underwater transmission cables across the Strait of Georgia, British Columbia, Canada. In the model, a total of six sediment categories from fine silt to medium sand were classified and simulated together in terms of sampled sediment characteristics. The model results were obtained with a trenching rate of 300 m/h and two trench sizes, a wide trench of 1.0 m wide  1.0 m deep and a narrow trench of 0.2 m wide  1.0 m deep. The amount of sediment that is suspended above the trench was taken to be 30% of the total volume for the wide trench and 25% for the narrow trench. The detailed model results of total suspended sediment values, plumes and depositions are reported in this paper.

/pdf/sediment-plume-and-deposition-modeling-of-removal-and-21kamru63a.pdf

Sediment Plume and Deposition Modeling of Removal and Installation of Underwater Electrical Cables on Roberts Bank, Strait of Georgia, British Columbia, Canada

The three-dimensional, coastal circulation numerical model COCIRM-SED was recently adapted and optimized to simulate and predict the flows in southern Discovery Passage and Canoe Pass, BC, Canada. These model results provided reliable, detailed flow information for use in assessing potential locations of installing and operating underwater tidal current turbines. In the application of modeling flows in southern Discovery Passage, the model involved tidal forcing with 69 constituents at open boundaries as well as the effects of the Campbell River freshwater input and the Coriolis. Detailed hourly model flows for typical neap and spring tides were extracted for use in the site assessment of potential locations for tidal current turbines. In the other application of modeling flows in Canoe Pass, the model was used to predict the water flows and water levels through Canoe Pass if the dam in Canoe Pass, which has been in place since the 1940’s, were completely removed and replaced by a passage of 40 m wide between Quadra and Maude Islands. In both studies, the model went through extensive calibration and verification processes using available measurements of water levels and ocean currents at various sites in the modeling areas. It was demonstrated that the 3D model has very good capabilities for simulating water level and currents in both model areas under different conditions.

/pdf/applications-of-3d-coastal-circulation-numerical-model-in-4yaw4h0ftz.pdf

Applications of 3D Coastal Circulation Numerical Model in Assessing Potential Locations of Installing Underwater Turbines

A three-dimensional, finite difference coastal circulation numerical model, ASL-COCIRM, was adapted to examine the possible recirculation of cooling water in the Burrard Generating Station, Canada. The model resolved the near-field zone of the cooling water buoyant jet and intake using a very fine grid size (2.5 m by 2.5 m in the horizontal), which allowed the cooling water outlet pipe and intake to be represented in a realistic manner. The near-field model was then nested within the large model domain of the far-field zone of cooling discharge receiving water. Model calibration and verification results demonstrate that the model has the capability of adequately capturing the overall behavior of the buoyant jet and quantitatively investigating the waste heat recirculation into the intake and the consequent effect on the efficiency of power plants.

/pdf/numerical-modeling-study-of-cooling-water-recirculation-a6c7xpgzmv.pdf

Jianhua Jiang

Papers

Modeling Sediment Disposal in Inshore Waterways of British Columbia, Canada

3D Numerical Modeling of Flows at the Confluence of the Columbia and Pend d'Oreille Rivers

Sediment Plume and Deposition Modeling of Removal and Installation of Underwater Electrical Cables on Roberts Bank, Strait of Georgia, British Columbia, Canada

Applications of 3D Coastal Circulation Numerical Model in Assessing Potential Locations of Installing Underwater Turbines

Numerical Modeling Study of Cooling Water Recirculation