北黄海水中辐照度的分布变化特征

本文对北黄海５次现场调查中获得的水中辐照度资料，应用统计分析方法，建立辐照度随水深变化的关系模式，分析辐照度的垂直衰减特性。结果表明：辐照度随水深按指数函数规律衰减；辐照度垂直衰减系数Ｋ有明显的季节变化和区域特征；不同水层的Ｋ值各不相同，Ｋ的变化存在分层结构。

Types and District Divistions of Seawater Intrusion Concerning Southern Coast of Laizhou Bay

The southern coast of Laizhou Bay in the Bohai Sea is the most serious disastrous coastal zone in China in the respect of seawater intrusion. We can divide seawater intrusion (in a wider sense) into two basic types based on the origins of seawater: the underground saline water intrusion originationg from ancient seawater (including ordinary underground saline water and underground brine) which was stored in the shallow sedimentary strata of the Quaternary and the seawater intrusion (in a narrow sense) originating from modern seawater.They differ distinctly in the mechanism of their genesis and harm. The underground brine intrusion is a special type of intrusion which causes the highest level of disasters. Coastal geomophology and hydrogeologic environments of the Quaternary are the main factors that control district divisions of seawater intrusion. Various coastal zones of the southen coast of Laizhou Bay which have different coastal environments form three types of intrusion, namely, the seawater intrusion type, the underground saline water intrusion type and the mixed seawater-saline water intrusion type.According to these types, it can be divided into four intrusion districts, namely, the seawater intrusion district of the northern coast of Laizhou City, the mingled intrusion district of seawater and saline water in the estuarine plain of the Jiaolaihe Shahe rivers, the seawter saline water mingled intrusion district in the estuarine plain of the Weihe river (in the north of Changyi county), and the underground saline water intrusion district in the north plain of Shouguang county. Such district divisions will be useful to the engineering project for the prevention and control of disasters due to seawater intrusion.