Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate

M.R. Heath, A.D. Sabatino, N. Serpetti, R.B. O’Hara Murray

Research output: Chapter in Book/Report/Conference proceedingChapter

37 Citations (Scopus)

Abstract

The depth to which sunlight penetrates below the sea surface is one of the key factors determining the species composition and productivity of marine ecosystems. The effects range from the rate and fate of primary production, through the performance of visual predators such as fish, the potential for refuge from predators by migrating to depth, to the scope for seabed stabilisation by algal mats. Light penetration depends partly on spectral absorption by seawater and dissolved substances, but mainly on the scattering caused by suspended particulate material (SPM). Some of this SPM may be of biological origin, but in coastal waters the majority is mineral material originating ultimately from seabed disturbance and land erosion, the latter being deposited in the sea by rivers and aerial processes. SPM is maintained in the water column or deposited on the seabed depending on combinations of hydrodynamic processes including baroclinic (density-driven) or barotropic (mainly tidal and wind driven) currents, and wave action (Ward et al. 1984; Huettel et al. 1996). Since tidal and wave energy extraction must alter these hydrodynamic properties at some scales depending on the nature of the extraction process, we can expect some kind of impact on the concentration of the SPM. If these are large enough, we may have to consider the extent to which these may impact the underwater light environment and the local or regional ecology.

Whilst several coupled hydrodynamic-sediment models exist to predict SPM distributions in aquatic systems, their skill level in open coastal and offshore marine waters is acknowledged to be relatively low. This is largely because the processes are not well understood and the formulations are largely based on empirical relationships rather than fundamental physical principles. The models are also highly demanding in terms of calibration data and computational resources. Hence their utility for predicting relatively subtle effects arising from changes in flow or wave environments due to energy extraction devices seems rather low. Here, we summarise the key mathematical functions describing the processes involved in sediment suspension, and propose a lightweight one-dimensional (vertical) model which can be used to scope the effects of changes in flow and wave energy on SPM.
LanguageEnglish
Title of host publicationTerawatt Position Papers
Subtitle of host publicationA 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment
EditorsJonathan Side
Place of PublicationSt Andrews
Pages143-166
Number of pages24
Publication statusPublished - 30 Sep 2015

Fingerprint

Suspended sediments
wave energy
suspended sediment
climate
Hydrodynamics
hydrodynamics
Sediments
predator
wind-driven current
algal mat
Water
Describing functions
Aquatic ecosystems
wave action
Ecology
material
Seawater
marine ecosystem
refuge
Fish

Keywords

  • marine renewable energy
  • sediment
  • model

Cite this

Heath, M. R., Sabatino, A. D., Serpetti, N., & O’Hara Murray, R. B. (2015). Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate. In J. Side (Ed.), Terawatt Position Papers: A 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment (pp. 143-166). St Andrews.
Heath, M.R. ; Sabatino, A.D. ; Serpetti, N. ; O’Hara Murray, R.B. / Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate. Terawatt Position Papers: A 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment. editor / Jonathan Side. St Andrews, 2015. pp. 143-166
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Heath, MR, Sabatino, AD, Serpetti, N & O’Hara Murray, RB 2015, Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate. in J Side (ed.), Terawatt Position Papers: A 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment. St Andrews, pp. 143-166.

Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate. / Heath, M.R.; Sabatino, A.D.; Serpetti, N.; O’Hara Murray, R.B.

Terawatt Position Papers: A 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment. ed. / Jonathan Side. St Andrews, 2015. p. 143-166.

Research output: Chapter in Book/Report/Conference proceedingChapter

TY - CHAP

T1 - Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate

AU - Heath, M.R.

AU - Sabatino, A.D.

AU - Serpetti, N.

AU - O’Hara Murray, R.B.

PY - 2015/9/30

Y1 - 2015/9/30

N2 - The depth to which sunlight penetrates below the sea surface is one of the key factors determining the species composition and productivity of marine ecosystems. The effects range from the rate and fate of primary production, through the performance of visual predators such as fish, the potential for refuge from predators by migrating to depth, to the scope for seabed stabilisation by algal mats. Light penetration depends partly on spectral absorption by seawater and dissolved substances, but mainly on the scattering caused by suspended particulate material (SPM). Some of this SPM may be of biological origin, but in coastal waters the majority is mineral material originating ultimately from seabed disturbance and land erosion, the latter being deposited in the sea by rivers and aerial processes. SPM is maintained in the water column or deposited on the seabed depending on combinations of hydrodynamic processes including baroclinic (density-driven) or barotropic (mainly tidal and wind driven) currents, and wave action (Ward et al. 1984; Huettel et al. 1996). Since tidal and wave energy extraction must alter these hydrodynamic properties at some scales depending on the nature of the extraction process, we can expect some kind of impact on the concentration of the SPM. If these are large enough, we may have to consider the extent to which these may impact the underwater light environment and the local or regional ecology.Whilst several coupled hydrodynamic-sediment models exist to predict SPM distributions in aquatic systems, their skill level in open coastal and offshore marine waters is acknowledged to be relatively low. This is largely because the processes are not well understood and the formulations are largely based on empirical relationships rather than fundamental physical principles. The models are also highly demanding in terms of calibration data and computational resources. Hence their utility for predicting relatively subtle effects arising from changes in flow or wave environments due to energy extraction devices seems rather low. Here, we summarise the key mathematical functions describing the processes involved in sediment suspension, and propose a lightweight one-dimensional (vertical) model which can be used to scope the effects of changes in flow and wave energy on SPM.

AB - The depth to which sunlight penetrates below the sea surface is one of the key factors determining the species composition and productivity of marine ecosystems. The effects range from the rate and fate of primary production, through the performance of visual predators such as fish, the potential for refuge from predators by migrating to depth, to the scope for seabed stabilisation by algal mats. Light penetration depends partly on spectral absorption by seawater and dissolved substances, but mainly on the scattering caused by suspended particulate material (SPM). Some of this SPM may be of biological origin, but in coastal waters the majority is mineral material originating ultimately from seabed disturbance and land erosion, the latter being deposited in the sea by rivers and aerial processes. SPM is maintained in the water column or deposited on the seabed depending on combinations of hydrodynamic processes including baroclinic (density-driven) or barotropic (mainly tidal and wind driven) currents, and wave action (Ward et al. 1984; Huettel et al. 1996). Since tidal and wave energy extraction must alter these hydrodynamic properties at some scales depending on the nature of the extraction process, we can expect some kind of impact on the concentration of the SPM. If these are large enough, we may have to consider the extent to which these may impact the underwater light environment and the local or regional ecology.Whilst several coupled hydrodynamic-sediment models exist to predict SPM distributions in aquatic systems, their skill level in open coastal and offshore marine waters is acknowledged to be relatively low. This is largely because the processes are not well understood and the formulations are largely based on empirical relationships rather than fundamental physical principles. The models are also highly demanding in terms of calibration data and computational resources. Hence their utility for predicting relatively subtle effects arising from changes in flow or wave environments due to energy extraction devices seems rather low. Here, we summarise the key mathematical functions describing the processes involved in sediment suspension, and propose a lightweight one-dimensional (vertical) model which can be used to scope the effects of changes in flow and wave energy on SPM.

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Heath MR, Sabatino AD, Serpetti N, O’Hara Murray RB. Scoping the impact of tidal and wave energy extraction on suspended sediment concentrations and underwater light climate. In Side J, editor, Terawatt Position Papers: A 'toolbox' of methods to better understand and assessthe effects of tidal and wave energy aarrays on the marine environment. St Andrews. 2015. p. 143-166