Relation Between Natural Cleansing Effect And
Angularity Of Coastal Gravel
Author(s)
S. Hamada, N. Sawano & R. Aps
Abstract
Serious environmental contamination will arise once spilled oil hits the coastal
area. A gravel beach is commonly hard for oil recovery because these areas are
hard to approach in order to conduct cleanup work. Also, stranded oil will easily
be penetrated into the coastal sediment of gravel. In this study, energy of wave
exposure was analyzed using the method of image analysis to gravel shapes. As
a result, the shape of gravel on a beach is affected by the energy of wave and
then provides natural cleansing ability. These effects were examined by an actual
oil spill by \“Nakhodka” which happened in 1997. In the field survey, projected
images of cobble-sized andesitic gravel were taken by a digital camera. Then
shapes of them were analyzed by the software \“ImageJ” and a common
spreadsheet. All the images were changed to 720-angled polygon then \“bending
angles” were measured to decide \“Angularity Indexes” of gravel. Oil residual
time of monitoring points of Nakhodka and the indexes were examined and then
a strong correlation coefficient (R2=0.858) has been observed. Also, the natural
cleansing ability for oil can be estimated by image analyses of coastal gravel.
Keywords: oil spill, gravel beach, ESI mapping, risk assessment.
Keywords
oil spill, gravel beach, ESI mapping, risk assessment
Related Book
Other papers in this volume
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