我国北方4 ka B.P.前后异常洪水事件的初步研究

PRELIMINARY STUDY ON THE FLOOD EVENTS ABOUT 4 ka B.P. IN NORTH CHINA

史前异常洪水事件的初步调查表明 ,4kaB .P .前后是我国北方异常洪水多发的时期 ,黄河流域、淮河流域和海河流域在这一时期普遍出现不同形式的史前异常洪水事件。异常洪水事件的出现与当时的降温事件有密切的关系 ,气候变冷引发的相对湿度加大和降雨量增多可能是造成这次异常洪水事件的主要原因。出现于华夏文明诞生前夕的史前异常洪水事件对华夏文明的演进势必会产生重大影响 ,在黄河上游的山间盆地和下游的黄淮海平原 ,异常洪水给人类生存环境带来严重的破坏 ,导致这些地区早期文明的衰落 ;而位于我国地貌大势二级阶梯与一级阶梯之间的中原地区 ,尽管洪水也给人类生存环境造成严重的威胁 ,但它并没有导致早期文明的衰落 ,恰恰相反 ,先民们利用有利的地貌条件 ,通过与洪水的争斗 ,促进了文化的发展和华夏文明的诞生。

The preliminary study on the prehistoric flood events showed that the period of 4 ka B.P. or so was a high frequency flooding period in North China. The extreme flood disasters often occurred at the Huanghe River Basin, Huaihe River Basin and Haihe River Basin where lots of geological evidences were found at Guanting Basin located on the upper reaches of Huanghe River, Xinzhai and Mengzhuang in Henan Province, Taosi in Shanxi Province and Huang-Huai-Hai plain on the lower reaches of Huanghe River, Haihe River and Huaihe River. The evidence included the older terraces buried by the younger flood deposits, the floodplain splays, floodplain, alluvial fans and debris flow carried by the mountainous torrents and archaeological sites covered or destroyed by the flood, etc. The spore-pollen analysis indicated that the flooding period was rather cold and wet than before and after, responding to the worldwide cold event at 4 ka B.P. or so. The cold event was accompanied by relative high humidity and heavy rainfall, consequently prehistoric floods occurred widely. The flooding period influenced the development of Chinese Civilization profoundly. In the region of the upper and lower reaches of the Huanghe River, the extreme floods destroyed the environment in which man lived and resulted in the ancient civilization collapse, while the floods accelerated the cultural development and speeded the Chinese Civilization formation in the region of the middle reaches of the Huanghe River due to the special geomorphic settings. The Central China, which located in the transition area of the upper step and middle step of Chinese topography, is featured with the broad loess tableland. Though the floods threaten the past man, the flooding area was limited. The prehistoric man struggled against the floods by the advanced technology and favored geomorphic conditions for a long time, and speeded the development of early civilization. In the fight against the floods, the past man living in the region of the middle reaches of the Huanghe River improved the level of the productivity, advanced the technology and developed the ability of organization, even set up the first dynasty, the Xia Dynasty. Someone assumed that the Chinese Civilization resulted from the fight against the flood. This viewpoint demanded further detailed study.