London and the Tidal Thames, 1250-1550: Marine Flooding, Embankment and Economic Change

The project investigated changes in the human and natural environments of the marshlands bordering the tidal river Thames and the Thames Estuary between 1250 and 1550. At the beginning of this period the marshlands had largely been drained and protected by banks or walls, so that they could be used for arable and pastoral farming. During the three centuries studied, however, many of these reclaimed marshes were flooded by the sea or by freshwater inundation. The causes were partly natural and partly human. Major flooding events may have become more common, and clusters of North Sea storm surges occurred, in which winds and tides combined to thrust large quantities of sea-water into the Thames Estuary, overwhelming flood defences. At the same time, declining population after c.1300, and associated agricultural recession, meant that it was no longer so profitable to defend the marshes against the sea. As a result, especially after the 1370s, many marshes flooded, and attempts to recover them were given up. Among the areas most affected were parts of the Barking, East Ham and Dagenham marshes, the Isle of Dogs, Erith and Lesnes marshes and the marshes around the mouth of the river Medway. In these and other locations fishing, fowling and the cutting of reeds and rushes replaced farming as the main sources of employment and income. Londoners complained about some of the effects of flooding, but may have benefited from the ‘retreat’ from the down-river marshes, which reduced the flood risk to Southwark, Bermondsey and other vulnerable suburbs.

该项目研究了1250至1550年间，毗邻泰晤士河潮汐河段及泰晤士河口的沼泽地在人类与自然环境方面的变化。在此时期之初，沼泽地大多已完成排水整治并以堤坝或围墙防护，以便用于耕作与畜牧。然而，在研究的三个世纪中，许多此类开垦的沼泽地遭海水淹没或淡水泛滥。其原因兼具自然与人为因素：大型洪水事件可能愈发频繁，且北海风暴潮群发性出现——风与潮汐共同作用，将大量海水涌入泰晤士河口，冲垮防洪设施。与此同时，约1300年后人口减少及随之而来的农业衰退，意味着防御沼泽免受海水侵袭的经济效益不再显著。因此，尤其在1370年代以后，许多沼泽被淹没，恢复这些沼泽的尝试也被放弃。受影响最严重的区域包括巴金、东哈姆及达格纳姆沼泽的部分区域、狗岛、埃里斯与莱斯尼斯沼泽，以及梅德韦河河口周边的沼泽。在这些区域及其他地点，捕鱼、捕鸟及收割芦苇与灯芯草取代耕作，成为主要的就业与收入来源。伦敦人对洪水的部分影响表示不满，但可能从下游沼泽的退垦（retreat from the down-river marshes）中获益，这降低了南华克、伯蒙德赛（Bermondsey）及其他易受洪水影响郊区的洪水风险（flood risk）。