頁籤選單縮合
題 名 | 碎波帶流場與懸浮輸砂之觀測分析=Observations of Currents and Suspended Sediment Concentrations in the Surf Zone |
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作 者 | 林柏青; 周憲德; 何良勝; 江玟德; | 書刊名 | 海洋工程學刊 |
卷 期 | 9:2 2009.06[民98.12] |
頁 次 | 頁149-175 |
分類號 | 443.1 |
關鍵詞 | 碎波帶; 懸浮漂砂; 近岸流; Surf zone; Suspended sediment concentration; Nearshore currents; |
語 文 | 中文(Chinese) |
中文摘要 | 本文以超音波式剖面流速儀、電磁式流速計、光學式濁度計及水位計等整合式儀器組於台南黃金海岸之碎波帶及近岸200m內進行斷面流場與懸浮漂砂濃度分佈觀測,並據以分析碎波帶內瞬時底床剪應力與懸浮質濃度分佈之關係,結果顯示碎波帶內砂懸浮移動之臨界Shields數約爲0.166,較前人計算得Φ(下標 crs)=0.175稍小,此由於碎波帶內底床上之沙漣結構會增加底流之剪應力所致。另外底床上之懸浮砂量峰值與剪速度峰值之間有時間延遲現象,延遲時間由岸向碎波點增加,但在碎波點外此延遲現象則消失不見。本文根據現場觀測之剪速度與懸浮總砂量關係得出其經驗公式,可用於近岸碎波帶輸砂量推算與海岸漂砂數值模擬之參考。 |
英文摘要 | Nearshore currents and suspended sediment concentration are studied by employing Acoustic Current Profilers, Electromagnetic Current Meters and Turbidity Merters at Tainan coastal line. Instantaneous bed shear stress and the vertical distribution of suspended sediment concentration in the surf zone are measured and analyzed. It is shown that the critical Shields parameter for saltation/suspension is about 0.166, which is a little smaller than that proposed by Li et al. (1997). He suggested that the ripple-enhanced shear velocity have to be used to determine the initiation of bed load transport when ripples are present. Time lags between peak suspended sediment concentration and bed shear velocity are also observed. The lag increases from shoreline to the break point due to depth and time increase for falling particles. Finally, a lag-time modified empirical formulation between suspended load and bed shear velocity is obtained. |
本系統中英文摘要資訊取自各篇刊載內容。