Difference between revisions of "Template:This weeks featured article"

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(Undo revision 20042 by Wouter Kreiken (Talk))
(Undo revision 20041 by Wouter Kreiken (Talk))
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== Groynes ==
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== Environmental risk assessment of marine activities ==
  
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This article focuses on '''Ecological Risk Assessment (EcoRA) of Marine activities'''. We first describe the general aspects and steps of the ERA process that most risk assessments are confronted with. The application of environmental risk assessment of marine activites is then illustrated in a case study focusing Merchant Shipping in the [[Case study risk analysis of marine activities in the Belgian part of the North Sea|Belgian Part of the North Sea]] (BPNS).
  
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[[Image:File1.jpg|350px|thumbnail|right|Figure 1: Scheme of interaction of groynes, waves, currents and shore]]
 
  
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'''Introduction'''
  
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A [[groyne]] is an active structure extending from shore into sea, most often perpendicularly or slightly obliquely to the shoreline. Adequate supply of sediment and existence of satisfactorily intensive longshore sediment transport are the sine qua non conditions of groynes efficiency.
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In broad terms, risk assessment is the procedure in which the risks posed by inherent hazards involved in processes or situations are estimated either quantitatively or qualitatively. Environmental Risk Assessments (ERA) are carried out to examine the effects of an entity or agent on humans (Health Risk Assessment) and [[ecosystems]] (Ecological Risk Assessment).
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Catching and trapping of a part of sediment moving in a surf zone (mainly in a longshore direction), as well as reduction of the sediment amount transported seawards, are the principle functions of the [[groyne]].
 
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As revealed by experiments, during weak and moderate wave conditions, the groynes partly dissipate energy of water motion and lead to sand accumulation in the vicinity of a shore, thus causing its accretion. Under storm waves, mainly approaching the shore perpendicularly, the role of the groynes decreases and a beach is partly washed out.
 
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Groynes are frequently used. However, applied as a self-contained shore protection measure it is a very dubious solution. This is because of unfavourable side effects which they can cause locally. Satisfactory supply of sand and existence of longshore sediment transport are fundamental conditions for efficiency of groynes. The groins role distinctly increases if they are applied together with other (soft) shore protection measures, like artificial [[beach nourishment]] or [[shore nourishment]].
 

Revision as of 13:03, 25 March 2008

Environmental risk assessment of marine activities

This article focuses on Ecological Risk Assessment (EcoRA) of Marine activities. We first describe the general aspects and steps of the ERA process that most risk assessments are confronted with. The application of environmental risk assessment of marine activites is then illustrated in a case study focusing Merchant Shipping in the Belgian Part of the North Sea (BPNS).


Introduction

In broad terms, risk assessment is the procedure in which the risks posed by inherent hazards involved in processes or situations are estimated either quantitatively or qualitatively. Environmental Risk Assessments (ERA) are carried out to examine the effects of an entity or agent on humans (Health Risk Assessment) and ecosystems (Ecological Risk Assessment).

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