南港—北槽洪枯季沿程水沙盐特性分析*

利用2012年2月及8月长江口南港—北槽大、小潮水文测验资料，从涨落潮历时、流速、含沙量及含盐度等方面 分析了南港—北槽洪枯季水沙盐纵向及垂向分布特征以及潮周期内含沙量变化特性。分析表明：南港—北槽沿程各垂线落 潮平均历时洪季整体较枯季长，涨潮平均历时洪季整体较枯季短，且小潮期洪、枯季的这种差异更为明显；南港—北槽洪 季落潮流速普遍大于枯季，涨潮流速普遍小于枯季；小潮期涨潮平均流速会出现近底层较表层大现象， 且CSW-CS3出现滞 流点；北槽中段—口外段洪季含沙量及垂向差异均较枯季大，南港圆圆沙段及北槽上段枯季含沙量较洪季大；潮周期内北 槽中段各垂线上层含沙量均较小，且变化幅度相对较小，但下层含沙量变化达数倍乃至十几倍之多，且涨憩时段近底层含沙 量可能特别高；洪枯季北槽中段均存在盐水楔，其位置洪季偏上、枯季偏下，最大浑浊带洪枯季位置变化与此基本一致。

Characteristics of water, sediment and salinity from south channel to north passage during flood and drought

The hydrological observations in both spring and neap tides are carried out in February and August respectively. Based on these data , this paper studies the changing characteristics of water , sediment and salinity from the south channel to the north passage. Conclusions are drawn as follows: 1) The ebb tide duration is longer in the flood season while the rise tide duration is longer in the dry season on the whole. 2) The average flow velocity of the ebb tide is generally bigger in the flood season while the flood current speed is generally bigger in the dry season. During the period of neap tide, there exists the phenomenon that the average velocity of the flood tide near the bottom is bigger than the surface. 3) The value and vertical difference of sediment is larger in the flood season from midstream of the north channel to the water area outside. From the south channel to the upper reach of the north channel, the value of sediment is larger in the dry season. 4) There exists saltwater wedge in the midstream of the north channel which is upper in the dry season.