应用ADP对虎门洪季悬沙浓度的观测研究

Survey and Analysis on SSC with ADP during Spring Tide in Flood Season in Humen Estuary

文章根据ADP(声学多普勒流速剖面仪)的声学观测原理,用2004年虎门洪季大潮期间的水流、泥沙观测资料,分析ADP应用于悬沙浓度观测的可行性,经过声强信号校正和浓度拟合分析,得到虎门深槽C站悬沙浓度的估测式。结果显示,悬沙浓度垂线拟合程度高于同层拟合,总体能达到精度要求。进一步对C站的浓度分析表明,尽管泥沙颗粒较细,浓度大小和垂线分布的变化仍然明显滞后于水流,不同涨落时段浓度剖面滞后规律不一样,上、下水层浓度时间变化也不尽相同,特别是转流时段下层浓度增加,浓度值在高高潮后的落憩附近达到了周期内最大。因此对潮汐河口悬沙运动的深入分析和模拟研究必须考虑泥沙运动的滞后因素和转流时紊动结构的变化才能更符合实际。

On the basis of acoustic principle, a series of ADP （]MHz） acoustic signal outputs data, which came from current survey of spring tides in flood season at Humen sub-estuary in 2004, were calibrated and fitted with in situ measurements data of suspended sediment concentration （SSC）. Results were satisfactory on the whole and then a relationship was derived between the signal output from ADP and SSC. It was found that in the deep channel the SSC process as well as its vertical profile adaptation still got behind the tidal current even with fine grain. The variety of SSC in upper layer and lower layer was not the same. Around veer time the SSC in lower layer often increased and can reach the maximum of the period near the nap time after higher high tide. The sediment movement lag and the unique turbulent structure of veering current should be considered in the theoretical analysis and mathematical modeling of suspended sediment in tidal estuaries so as to be close to the reality.