CAJ | 학술논문

2010年1月1日至10日在长江口南支南港北槽航道弯道段内3个水文测站位CS1、CSW和CS8，观测得到大、中、小潮的潮位、流速、盐度和含沙量的时间序列。这些资料揭示了由盐度和含沙量引起的垂向层化的大、小潮和涨、落潮的潮周期变化特性。为定量了解航道弯道段水体的垂向混合程度，采用考虑含沙量后的水体密度来估算其梯度Richardson数(Ri)。在转流时刻，CS1和CSW站位的量级为101~102，水体呈现层化状态；在涨急、落急时，Ri量级为10-2~10-1，水体呈现强混合状态。CS8站位涨潮时的Ri在0.25~5，落潮时平均为10-2量级。3个水文测站位，涨潮时的层化均强于落潮时；大潮时的层化程度最强，而小潮时的层化持续时间最长；均存在潮汐应变的现象，且以非持久性的SIPS层化为主。采用Simpson等[2]的公式，估算了长江口北槽航道弯道段内水体由河口环流、潮汐应变和潮汐搅动引起的势能变化率。潮汐应变是水体层化的主要动力机制，而河口环流引起的势能变化率比潮汐应变和潮汐搅动引起的小102~103量级。
2010년1월1일지10일재장강구남지남항북조항도만도단내3개수문측참위CS1、CSW화CS8，관측득도대、중、소조적조위、류속、염도화함사량적시간서렬。저사자료게시료유염도화함사량인기적수향층화적대、소조화창、락조적조주기변화특성。위정량료해항도만도단수체적수향혼합정도，채용고필함사량후적수체밀도래고산기제도Richardson수(Ri)。재전류시각，CS1화CSW참위적량급위101~102，수체정현층화상태；재창급、락급시，Ri량급위10-2~10-1，수체정현강혼합상태。CS8참위창조시적Ri재0.25~5，락조시평균위10-2량급。3개수문측참위，창조시적층화균강우락조시；대조시적층화정도최강，이소조시적층화지속시간최장；균존재조석응변적현상，차이비지구성적SIPS층화위주。채용Simpson등[2]적공식，고산료장강구북조항도만도단내수체유하구배류、조석응변화조석교동인기적세능변화솔。조석응변시수체층화적주요동력궤제，이하구배류인기적세능변화솔비조석응변화조석교동인기적소102~103량급。
Field measurements are made of time series of tidal elevation, current velocity, salinity and suspended sediment concentration at three hydrological gauging stations CS1, CSW and CS8, within the curved navigational channel of the north passage of the south branch/south channel of the Changjiang River estuary, on spring, moderate and neap tides, on 1 to 10 January 2010. Those data display the spring/neap and flood/ebb tidal variability in the vertical stratification caused by salinity and suspended sediment concentration.To quantitatively evaluate the potential of vertical mixing within the curved channel, we estimate the gradient Richardson number (Ri) using the density of water after taking suspended sediment concentration into account. Ri at stations CS1 and CSW can be in the order of 101~102 at the turning of the tide. The strongest mixing with the order of 10-2~10-1 occurs at the maximum flood and ebb tides. Ri at station CS8 is between 0.25 and 5 at the flood tide and of the order of 10-2 at the ebb tide. At the three hydrological gauging stations, stratification appears to be stronger at the flood tide than at the ebb tide. Stronger stratification is present on the spring tide, while stratification lasts longer on the neap tide.Following Simpson, we estimate the rate of change in the potential energy of the water column within the curved channel caused by tidal straining, estuarine circulation, and tidal stirring. Tidal straining is present at the three hydrological gauging stations CS1, CSW and CS8. Strain induced periodical stratification is predominant at these locations. It is found that the tidal straining is the key mechanism for the stratification within the waters of the curved channel. The rate of change in the potential energy dut to estuarine circulation is smaller than that dut to tidal straining and tidal stirring by the order of 102~103.