应用走航式ADCP测量分析与验证金塘水道的高悬沙浓度  

Measurement and analysis of high suspended sediment concentration in Jintang Channel with vessel-mounted ADCP

作　　者：金魏芳[1] 梁楚进[1] 周蓓锋[1] 李俊德[1] 

机构地区：[1]卫星海洋环境动力学国家重点实验室,国家海洋局第二海洋研究所,浙江杭州310012

出　　处：《海洋学研究》2009年第3期31-39,共9页Journal of Marine Sciences

基　　金：浙江省重点河口港湾环境综合基础调查资助项目(ZJ908-01-01-2);我国近海海洋综合调查与评价专项资助项目(908-02-01-04)

摘　　要：在金塘水道西口门2006年冬季和2007年夏季大、小潮期间应用美国RDI公司生产的300kHz声学多普勒流速剖面仪（ADCP）进行25h的走航式断面观测，同步采集水样过滤获得悬沙浓度。实测断面流速、流向表明：落潮时流向为东南向，涨潮时分两股，靠近北仑为西南向，靠近金塘岛为西北向；夏季大潮最大流速为260cm／s，大于冬季大潮；观测期间断面悬沙浓度为0．4～1．5g／L，冬季大于夏季约0．3～0．5g／L；ADCP后向散射强度冬季大于夏季约5dB。应用实测CTD数据进行声吸收系数校正，通过计算，断面后向散射强度分布趋势基本不变。后向散射强度与悬沙浓度成正比，与水深成正比，垂向分布与潮时有关，冬季小潮水深增大时，后向散射强度反而减小。回归ADCP后向散射强度与水样悬沙浓度之间半经验半理论统计关系，发现冬季不成线性关系，夏季成线性关系，且相关性较好，相关系数为0．7，说明夏季较高浓度下后向散射强度可以表示悬沙浓度的大小。夏季大、小潮期间高分辨率的悬沙浓度断面数据分析表明，反演后的悬沙浓度值与流速成正比；近岸悬沙浓度大于断面中部；涨急和落急时同一水深高低含沙量值错落分布，涨憩和落憩则分层明显；大潮悬沙浓度大于小潮流约0．05g／L。断面两端点反演后的悬沙浓度与实测值比较，呈现半日潮含沙量双峰特征，夏季大潮反演后的悬沙浓度与实测值分布一致，实测值大干0．9g／L时，两者量值相差大，小潮则拟合很好。因此，应用走航式ADCP测量高悬沙浓度是可行的，它可大大提高测量效率，为获取现场悬沙浓度提供了一种新方法。One-day profile observation with vessel-mounted WHS300-kHz Acoustic doppler current profiler （ADCP） was conducted in the west mouth of the Jintang Channel during spring and neap tides, in winter 2006 and summer 2007. Data of currents and acoustic backseatters as well as water samples were synchronously collected. The result shows that the current direction was southeast during ebb tide, and southwest near Beilun northwest near Jintang island during flood tide. The max current speed reached 260 cm/s in summer spring tidewhich is greater than that in winter spring tide. The suspended sediment concentration （SSC） was about 40041 500 mg/L in the investigation, and that in winter is about 300-500 mg/L greater than that insummer, and the acoustic backscatter in winter is about 5 dB larger than in summer. Correction with different sound absorption coefficient calculated from CTD data resulted in similar acoustic backscatter distribution patterns. It can be seen that the higher acoustic backscatter coincides with the higher SSC, the water depth and the tide except during winter neap tide, when the intensity of the backscattered signal decreased with the increase of depth. Half-empirical half-statistical relation between ADCP regressed backscatter intensity and suspended sediment concentration （SSC） shows a good linear relationship in summer （0.7） but not in winter which means that the backscatter intensity can indicates SSC in summer. The analysis of high resolution SSC profile during spring and neap tide in summer shows that the inversed SSC value is in direct proportion to the current speed, the SSC near shore is greater than that in the middle of the profile; the SSC is increasing from the surface layer to the bottom layer at flood fast tide and ebb fast tide but not during tidal flood and tidal ebb; the SSC at spring tide is about 50 mg/L greater than the neap tide. The comparison between the inversed SSC at either end of the profile and the observed value presents double peak characteristics of semi-

关 键 词：ADCP 悬沙浓度 后向散射强度 金塘水道 

分 类 号：TV149.1[水利工程—水力学及河流动力学]