本文利用底碇式 ADCP 及 RCM 9 流速濁度計時間序列紀錄來探討愛河環境及後灣水域影響水中回聲強度（Echo Intensity, EI）的機制，研究結果顯示，在混濁的河口（例如愛河）環境下，由於豪雨使得洪流宣洩，造成愛河流速超過 1 ms-1，ADCP 所紀錄的 EI 值亦快速增加，其變化趨勢與濁度非常吻合，利用 Kim and Voulgaris（2003）的經驗公式，將 ADCP 第一個 bin 的 EI 值轉換成懸浮沉積物濃度（SSC），與由濁度值轉換成 SSC 的結果相比亦很相近，可見 ADCP 的 EI 值可以做為 SSC 的指標。本研究也將愛河所測得的流速剖面分佈帶入對數公式中以求得摩擦速度、粗糙長度等邊界層特性，在暴雨時的對數層高度幾乎佔了全部的河道水深（4 m），z0 則大約趨近於 1*10-3 m，而河床剪應力則高達 10 Pa 以上，在這麼高的剪應力作用下底質會被擾動而捲起懸浮。
另一方面，本研究也針對清澈的沿岸海域環境（例如後灣），探討海流與波浪對於 ADCP EI 值的影響。在冬季時海流的流速較強，示性波高則通常不大於 1 m。靠近海底的 ADCP EI 值主要是與海流大小成正相關，與波浪的相關性偏小，靠近海面 ADCP EI 值則與示性波高的相關性較大，這應該是由於波浪破碎捲入空氣所產生的氣泡效應，特別是在示性波高大於 0.5 m 時更為明顯。
在夏季期間，海流較小，但是由於西南季風沒有陸地的阻擋使得波高較大，尤其在颱風侵襲時示性波高可高達 4.5 m，巨浪所引起的海底軌道速度和底床剪應力會攪動底質產生懸浮，使得幾乎整個水層（約 15 m）的 ADCP EI 值均與波高的相關性良好，與海流的相關性較差。靠近海底的 ADCP EI 值和濁度紀錄幾乎沒什麼相關，這可能是因為此處的海水 SSC 太低。

In this study, bottom mounted ADCP and RCM 9 were deployed to collect time series data of current, turbidity and acoustic backscattered echo intensity (EI) in the estuarine environment near Love River and in the coastal waters of Howan. Our results indicate that in the torrential rain event, the Love River became very turbid with the flow speed exceeding 1.5 m/s. ADCP EI data also increase rapidly and correlate well with the turbidity data. Based on the empirical formula of Kim and Voulgaris (2003), the EI time series data of the first bin are converted into sediment suspension concentration (SSC), which compared reasonably well with those converted from the optical observations of turbidity. Therefore, ADCP EI data can be used as a good proxy of SSC. Velocity profiles measured by ADCP were also analyzed to obtain the friction velocity and roughness length according to the logarithmic relationship. The log layer height extended to almost full channel depth of 4 m during strong flows, the roughness lengths were about 10-3 m and the bottom shear stress reached 10 Pa. It is not surprising that bottom sediments are stirred under such a large shear stress.
The sediment suspension due to current and wave action in the rather clear coastal waters of Howan is also investigated by means of ADCP EI data. In winters the observed current speed is stronger while the wave height is smaller (Hs<1 m). It is found that the near-bottom ADCP EI data have better correlation with the current magnitude but poorer correlation with surface waves. On the other hand, the ADCP EI data near the sea surface become more dependent on the surface waves. This is possible due to the bubbles entrained by breaking waves, especially under the condition of Hs>0.5 m. In summers the observed current speed is weaker while the wave height is generally higher. In one typhoon event the observed Hs even reached 4.5 m. The calculated maximum orbital velocity at the bottom and bed shear stress generated by surface waves are sufficient to mobilize sediment. The ADCP EI data of the whole water column (about 15 m) correlate nicely with the wave height but correlate poorly with current magnitude. In contrast to the results of the Love River, the near-bottom ADCP EI data show a weak correlation with the turbidity observation.

摘要 I
Abstract III
謝誌 V
目錄 VI
表目錄 VIII
圖目錄 IX
第一章 前言 1
第二章 研究區域概況 3
2-1 愛河地理環境 3
2-2 愛河氣象與海象概況 4
2-3 後灣地理概況 5
2-4 後灣氣象與海象概況 6
第三章 實驗設計及方法 8
3-1 實驗設計與地點 8
3-2 儀器設備與設定 11
3-3 分析方法 12
第四章 研究結果 15
4-1 愛河觀測結果 15
4-2 後灣第一次實驗觀測結果 23
4-3 後灣第二次實驗觀測結果 33
第五章 討論與結論 42
5-1愛河底床邊界層特性 42
5-2 海水濁度與 ADCP EI 觀測值得比較 48
5-3 回聲強度轉換成懸浮微粒濃度（SSC） 51
5-4 ADCP EI 值隨著海氣象的變化 54
5-5 結論 58
第六章 參考文獻 61

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