Holocene Extraordinary Floods and Climatic Change in the Middle Yellow River Basin of China (PAP017824)

Código

PAP017824

Autores

Chunchang Huang

Tema

Urban Floods

Resumo

Sedimentary records of pre-historical palaeoflood events were investigated in the middle Yellow River basin by using the multi-disciplinary methods. Several bedsets of flood slackwater deposits were identified in the Holocene loess-soil sequences on the riverbanks along the tributaries and main stream of the Yellow River. They were differentiated from aeolian loess and soils and slope deposits by the parallel and waving beddings and the distinctive stratigraphic breaks separating individual flood events. Chronology of the events was established by OSL dating, checked by 14C dating and archaeological identification of the anthropogenic remains retrieved from the sediment sequences. The results show that successive extraordinary floods occurred during the episodes of 4200?4000 a BP and 3200?3000 a BP during the Holocene. The riverbank pre-historical settlements were inundated and destroyed repeatedly by the overbank flooding. These extraordinary flood events are related to the global climatic events occurred during 4200?4000 a BP and the climatic decline at 3100 a BP, which were believed to be characterized by droughts in Africa, India and Mediterranean regions. This work provides solid evidence that both severe droughts and extreme floods were parts of the climatic variability during abrupt climatic event and climatic decline in the semi-arid to sub-humid monsoonal zones. The results have important implications in understanding global change and the impact on hydrological system.