中文摘要：

本文主要通过对历史文献和考古资料的分析，重建延芳淀地区辽代之前、辽代、辽代以后的水环境变迁情况。即：辽代之前，该地区处于漯水和潞水两条河流下游漫流区，是一个典型的河网沼泽平原；辽代，出现积水现象，形成湖泊；辽之后，渐渐地由成片湖泊解体为几个较小的湖泊，最后被开垦为农田。其中，辽代是延芳淀水域面积最大的时期，重点重建这一时期延芳淀积水四至范围。通过与中世纪中国东部温度及其他积水地区的比较，延芳淀出现在中世纪暖期最温暖的时段。这种大面积积水现象，可能和中世纪暖期渤海海平面上升波动有关。

英文摘要：

This article aims at rebuilding the water environment changes of the Yanfang Lake before Liao Dynasty, in Liao Dynasty and Liao Dynasty later, through an analysis of historical documents and archaeology matericals. That is： before Liao Dynasty, Yanfang Lake was a typical plain with waterways and marshlands, stituated in the flowing downstream aera of the Luo River and the Lu River; in Liao Dynasty, ponding appeared and the lake formed; Liao Dynasty later, the lake broke up into several smaller lakes and were reclaimed to farmlands later. Among the three, Liao Dynasty is the period with the largest water area of the Yanfang Lake and the article mainly rebuilding the range of Yanfang Lake in this period. By comparing with Eastern China temperture in MWP, 930-1100 AD lasted the longest warm period fluctuations in MWP. While the appearance of Yanfang Lake, happens to be within the 930-1100 AD, which in time has a good consistency. Judging from the time and space, Yanfang Lake ponding phenomenon may indicate that the medieval warm period in Bohai Sea level rise. Combined with the rest of the Bohai Sea and the sea-level changes in situation analysis, most of coastal sea level rising volatility during the MWP. Lake formed in the warmest time of that period. And this large area of pondings can indicate the sea level rise of Bohai Sea. Though coast have found meaningful evidence, but for the whole of the sea level along coast, in the volatility of the middle ages is not fully and need more information. Sea level rise is a global event, which required the evidence to contrast the rest of the world, to confirm that this event occurred on a global scale and the existence of regional differences.