RECOVERY OF SANDY BEACH AFTER TYPHOON WAVES – CASE STUDY ON CHIGASAKI COAST
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- ISHIKAWA Toshinori
- 中央大学研究開発機構
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- UDA Takaaki
- （一財）土木研究センターなぎさ総合研究所兼日本大学理工学部海洋建築工学科
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- SAN-NAMI Toshiro
- 海岸研究室（有）
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- HOSOKAWA Jun-ichi
- 神奈川県藤沢土木事務所なぎさ港湾部
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- KOGANE Hiroaki
- 神奈川県藤沢土木事務所なぎさ港湾部
Bibliographic Information
- Other Title
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- 高波浪時の急激な沖向漂砂と静穏時の緩やかな砂浜回復応答の実測
- コウハロウジ ノ キュウゲキ ナ オキコウヒョウサ ト セイオンジ ノ ユルヤカ ナ スナハマ カイフク オウトウ ノ ジッソク
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Abstract
<p> Beach topography quickly responds to the action of storm waves, resulting in erosion of the foreshore with accretion under the calm wave condition after the storm. The shore protection function of a sandy beach is reduced when a trough has been formed near the shoreline because of the increase in wave runup height. So, the observation of the beach recovery after the storm event is important. The response time required for the beach recovery after the storm, however, has not been sufficiently studied. This study aims to investigate these issues using the Narrow Multi-Beam survey data, wave data, and the sampling test of the seabed materials which were taken before and after the storm event, taking the Chigasaki coast as an example. It was found that the seabed shallower than 2 and 3 m depths was eroded by rapid offshore sand transport during the storm event with the deposition of sand in a zone between 3 and 5 m depths, and then the beach recovered within 1-2 years after the storm. It was also confirmed that the disappearance of a bar and trough occurred in 1-2 months under the conditions of HE = 0.5m, TE = 8s, H/L = 0.005 when the crown depth of the bar was smaller than approximately 2 m. Thus, the topography after the storm waves recovers within several months or 1-2 years depending on wave conditions and the crown depth of the bar.</p>
Journal
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- Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)
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Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 76 (2), I_547-I_552, 2020
Japan Society of Civil Engineers