coastal erosion prevention

31 2009 11 Proceeding of the 31st Ocean Engineering Conference in Taiwan National Chung Hsing University, November 2009

1* 2

1 2

50 98 6 0.5 0.8

Field experimental study on a soft protecting method for coastal erosion prevention Ta-Hsiung Peng* Chyan-Deng Jan

*Ph.D. Candidate, Department of Hydraulic and Ocean Engineering, National Chen Kung University

ABSTRACT

The structures which are used to protect coastal erosion are very expensive to construct and it is important to protect these structures from damage. Usually those structures like: embankments, breakwaters, jetties etc. are constructed by concrete and very rigid methods like tetrapod, groyne etc are used to protect those structures. But those rigid methods are not very effective always, because very high energy could not be absorbed by those methods. To protect the coastal erosion by reducing the energy, a flexible device is introduced which will reduce energy and protect coastline economically and environmentally as well. The flexible device is a combination of flexible wire net and stack of rings with soften blades attached with used tires. This flexible wire net is placed in between two stack of rings with soften blades. The stack of rings with soften blades is used to hold the flexible wire net and the flexible wire net is used to reduce the energy gently which helps to deposit the sediment in the coast. The device is placed at Shuang-Chun coastal area in Tainan County on June, 2009. The length of the device is 50.0 meters. The wave energy usually coming from sea is absorbing gently by the device and a typhoon called Linfa and Morakot passed on the device. The device has worked effectively during normal period and typhoon period as well and it has developed a very good amount of sediment deposition around the device. The observed results revealed that the sediment deposition depth around the device various from 0.5m to 0.8m.

Keywords: Stack of rings; soften blades; flexible wire net; reduce energy; coastal protection

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2007/2/28~2009/1/3 11 2

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(NSC97-2622-E006-024-CC1)

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H(m) 1 1 2 3 4 5 6 2 H1(98.05.17) -0.619 -0.820 -0.835 -0.816 -0.801 -0.660 -0.715 -0.815H2(98.07.26) 0.115 -0.123 -0.141 -0.064 -0.011 -0.107 -0.469 -0.246H3(98.08.15) -0.067 -0.104 -0.072 -0.044 -0.027 -0.058 -0.042 -0.046

H 0.552 0.716 0.763 0.772 0.774 0.602 0.673 0.769

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2 () (m) 0 10 20 30 40 50 60 70 80 90 100 110

98.05.17() 0.681 0.383 0.085 -0.213 -0.511 -0.746 -0.956 -1.176

98.07.26 1.62 1.132 0.92 0.7 0.48 0.26 0.04 -0.14 -0.183 -0.402

98.08.15() 1.67 1.316 0.961 0.673 0.482 0.292 0.105 0.048 0.015 -0.056 -0.167 -0.35

: 75m

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