Factors for intensified flood in the lower Yellow River from the Tang Dynasty to Northern Song Dynasty

Abstract

With the application of five year slide average of flood frequency analytical methods, the authors analyse the developing process of the Yellow River in the course of 510 years from the Tang Dynasty (TD), Five Dynasties (FV) to the Northern Song Dynasty (NSD), and explores several major flood afflicted consequences from TD to NSD It is found out a comparatively slight flood occurred at the beginning of TD, whereas severe floods occurred in the middle and late TD. Up till FV and NSD,the Yellow River was breached almost every year, the worst case with a couple of breaches in a year, and the most disastrous flood claimed a casualty of nearly one million people, unprecedented in the Yellow River flood disaster history The analyses and comparisons of the agricultural population migration in the middle Yellow River and from Hekouzhen to Longmen section from Eastern and Western Han dynasties, TD to NSD indicate that the ups and downs of the agricultural population in the middle reaches does not synchronize with flood frequency alteration in the lower reaches The evidence shows the flood of the lower reaches in TD was much slighter than that of Eastern Han, however the population in the middle reaches quadrupled that of EHD at that time Furthermore, population in the middle reaches in mid TD surpassed that of WHD and late NSD as well However, there was a relatively quiet time in the lower reaches in mid TD In accordance with the aforementioned, it can conclude that the local population growth did not contribute to the severe flood disasters in NSD The essay also investigates the conditions of land resources in the middle reaches and from Hekouzhen to Longmen section and concludes that the basin area and the valley plain could already fully satisfy the farming capacity, as a rule, it was unnecessary to open up the available slopes Thus farming activities can not be accountable for the severity of the flood disaster in the lower Yellow River After late TD, Dang Xiang ethnic group expanded their range of activity by establishing the feudal separatist regime in the whole Ordos Plateau and northern Shaanxi of the Loess Plateau and Xia Kingdom later in NSD, which featured the traditional grazing practice of nomadic nationality in this area accounting chiefly for soil desertification and flood disasters in the lower Yellow River