摘要
海河流域地处华北平原北部,位于中国北方半干旱—半湿润气候区,是水文气候变化的敏感区,洪涝灾害频发,重建区域古洪水历史是评估未来极端洪水灾害影响的关键,而该流域古洪水事件发生规律及其驱动机制的研究仍显不足。基于海河流域大清河北支新盖房分洪道全新世地层剖面,根据地层序列、岩性特征及沉积构造,结合沉积物粒度、磁化率等指标分析,识别出全新世以来的3期(6次)古洪水事件沉积。洪水沉积以中-细砂为主,黏土与粉砂含量较低,磁化率呈高值,指示强水动力条件下高磁性外源物质的输入。通过加速器质谱14C测年法(AMS14C)年龄限定3期古洪水事件的年代分别约为:8.4 cal ka BP、5.0~4.6 cal ka BP、4.1~3.7 cal ka BP。第1期洪水事件发生于全新世气候适宜期早期,处于8.2 ka事件的前兆期,为气候相对不稳定阶段。第2期洪水事件处于全新世气候适宜期晚期,东亚夏季风逐渐减弱,该期洪水主要受东亚季风控制。第3期洪水事件在时间上与全球性4.2 ka气候事件较一致,对应于全新世晚期季风持续衰退中的波动阶段,为弱季风条件下的偏湿气候期。大清河北支全新世古洪水序列与东亚夏季风强度波动及全球性气候事件密切相关,为揭示海河流域洪涝灾害发生规律及雄安新区韧性城市建设提供了科学依据。
[Objective]The Haihe River Basin,located in the northern part of the North China Plain,within the semi-arid and semi-humid climatic region of north China,is a sensitive area for hydroclimatic changes and experiences frequent flood disasters.Reconstructing the regional paleoflood history is crucial for assessing the potential impact of future extreme flood disasters.However,research on the occurrence patterns and driving mechanisms of paleoflood events in this basin remains insufficient.[Methods]Through analysis of stratigraphic sequences,lithological characteristics,sedimentary structures,and indicators such as sediment grain size and magnetic susceptibility,we identified deposits of three periods(six occurrences)of Holocene paleoflood events in the Xingaifang Flood Diversion Channel in the North Branch of the Daqing River within the Haihe River Basin.[Discussion]The flood deposits are primarily composed of fine to medium sand,with low clay and silt contents,and high magnetic susceptibility,indicating the input of highly magnetic materials under highenergy hydrodynamic conditions.The first period of flood events occurred in the early stage of the Holocene Climatic Optimum,during the precursor phase of the 8.2 ka event,when the climate was in a relatively unstable stage.The second period of flood events took place in the late stage of the Holocene Climatic Optimum,as the East Asian Summer Monsoon(which primarily controlled these floods)gradually weakened.The third period of flood events coincided temporally with the global 4.2 ka climate event,corresponding to a fluctuating phase within the late Holocene monsoon decline with a relatively humid climate under weak monsoon conditions.[Results]Based on AMS 14C dating,the periods of the three paleoflood events are constrained to approximately~8.4 cal ka BP,5.0–4.6 cal ka BP,and 4.1–3.7 cal ka BP,respectively.The Holocene paleoflood sequence of the North Branch of the Daqing River is closely related to fluctuations in the intensity of the East Asian Summer Monsoon and global climate events.This study provides a scientific basis for understanding flood disaster patterns in the Haihe River Basin and supports resilient urban planning in the Xiong'an New Area.
作者
王永
王燕校
杨劲松
田飞
袁路朋
WANG Yong;WANG Yanjiao;YANG Jinsong;TIAN Fei;YUAN Lupeng(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang 050061,Hebei,China)
出处
《地质力学学报》
北大核心
2025年第5期990-1005,共16页
Journal of Geomechanics
基金
中国地质调查局地质调查项目(DD20221648,DD20221645)
河北省自然科学基金项目(D2025504006)。
关键词
古洪水
全新世
粒度
大清河
雄安新区
Paleofloods
Holocene
grain size
Daqing River
Xiong'an New Area
