中国河口盐淡水混合特征研究

MIXING CHARACTERISTICS OF SALT WATER AND FRESH WATER IN CHINESE ESTUARIES

河口盐淡水混合受河口潮差、几何形态及淡水流量等诸多因素影响,并有着大小潮和洪枯季变化周期。本文在分析中国众多河口实测盐度分布资料的基础上,首次归纳了中国河口盐淡水混合的基本特征,给出数十个河口盐淡水混合的基本图式。并从高度分层型、部分混合型和强混合型三个类型,分别选择较典型的几个河口进行具体阐述。

The mixing process of salt water and fresh water in an estuary is in fluenced by many factors such as the estuarine geometry, tidal range and riverine flows etc. It changes with the spring-neap tide cycle and flood-dry season, therefore the mixing intensity in the form of fre-quency vector is used in this paper. there are nearly two thousand estuaries along chinese coastline, and of them about two hundred are big ones (the length of the river is more than 100 km). Based on the analysis of salinity data measured in lots of chinese estuaries, this paper first summarizes the mixing cha-racteristics of salt water and fresh water in chinese estuaries and gives their basic mixing pat-terns. In Chinese estuaries three mixing types are subdivided, namely the high stratified with salt wedge, the partially mixed and the well mixed. The partially mixed is dominant. Each of the kinds is illustrated by some typical estuaries respectively. The seasonal variation of the mixing type is expressed in such a way that the mixing in-tensity in rainy season would be weaker than in dry season. For example, the estuary of partia-lly mixed type would be a well mixed in dry season or a highly stratified in rainy season. Geographically, most of the estuaries in South China, including Changjiang estuary belong to the partially mixed type while those estuaries which empty into the East China Sea are of the well mixed type and a few of the estuaries along Northern China coastline belong to the highly stratified.