山东弥河流域现代洪水沉积特征与水动力过程反演  

Characteristics of modern flood deposits in the Drainage basin of Mi River,Shandong Province and the reconstruction of hydrodynamic processes

作　　者：李华勇 袁俊英 杨艺萍 梁志姣 李智慧 吴帅虎 张虎才 LI Huayong;YUAN Junying;YANG Yiping;LIANG Zhijiao;LI Zhihui;WU Shuaihu;ZHANG Hucai(School of Resources Environment and Tourism,Anyang Normal University,Anyang 455000,China;South China Sea Institute of Oceanography,Chinese Academy of Sciences,Guangzhou 510301,China;Institute for Ecological Research and Pollution Control of Plateau Lakes,School of Ecology and Environmental Science,Yunnan University,Kunming 650504,China)

机构地区：[1]安阳师范学院资源环境与旅游学院,安阳455000 [2]中国科学院南海海洋研究所,中国科学院边缘海与大洋地质重点实验室,广州510301 [3]云南大学生态与环境科学学院,高原湖泊生态与污染治理研究院,昆明650504

出　　处：《海洋地质与第四纪地质》2022年第2期178-189,共12页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金青年项目“云南阳宗海沉积物中细菌脱镁叶绿素含量的气候学意义及全新世古气候定量重建”(41807447);河南省自然科学基金青年项目“雅鲁藏布江中游极端洪水事件研究”(212300410101)。

摘　　要：随着全球气候变化加剧,强天气过程以及由此引发的洪水危害愈来愈严重。理解现代洪水沉积特征,不仅可以为减轻洪水灾害提供理论指导,而且也为识别古洪水沉积提供参照依据。2018年8月中旬,山东弥河流域受双台风影响发生洪涝灾害,对当地社会发展、人民生活造成严重影响。在对洪水淹没区考察基础上,于下游高河漫滩区、洪水沉积物保存完好的地点获取21.5 cm长岩芯MH1(含现代土壤),并进行了粒度、孢粉、磁化率、烧失量分析。结果显示:钻孔岩芯洪水层沉积物以黏土和细粉砂为主,平均砂含量仅为1.7%,反映洪水强度不大;洪水沉积层粒度可识别出7.9和30.0μm两个敏感组分,根据其含量变化特征,可将此次洪水过程划分为洪水初期、第一次洪峰、高水位期、第二次洪峰、退水期5个阶段;洪水沉积层烧失量显著高于土壤层,而磁化率值整体低于下伏土壤层;洪水层与土壤层孢粉特征无明显差异,表明两者孢粉组合均能反映小流域植被状况,但洪水堆积层孢粉丰度(7313.96粒/g)远高于下伏土壤层(1562.65粒/g)。实验结果揭示洪水沉积环境有利于孢粉富集,磁化率值可能反映土壤发育过程中磁性矿物的产生与积累(成壤强度),因此可作为识别古洪水层与古土壤层的参考指标,但其地理空间适用性有待进一步探讨。With the aggravation of global climate change,severe weather processes and resulted flood disasters become more and more serious nowadays.Understanding the characteristics of modern flood deposition,not only provide theoretical guidance for flood mitigation,but also offer evidence and referential benchmarks for the identification of paleoflood deposits and reconstruction of paleoenvironment.In the midAugust of 2018,two typhoons hit the drainage basin of the Mihe River in the northern Shandong Province and caused serious damage and economic loss.Based on the surveys of the flooded areas,a 21.5-cm-long sediments core labeled MH1,including modern soil,was drilled in the high floodplain of downstream area where flood deposits are well preserved,and the grain size,pollen,magnetic susceptibility,and loss-on-ignition are analyzed.The results suggest that flood layer deposits are mainly composed of clay and fine silt,and the average content of sand is only 1.7%,indicating that the flood intensity was quite low.Two environmentally sensitive grain size components,7.9μm and 30μm respectively,are identified in the flood sediment layer.According to the variation characteristics of sediments,the flood process can be divided into five stages:initial flooding,first flood peak,high-water level period,second flood peak,and flood recession period.The loss-on-ignition of flood sediment layer is also significantly higher than that of soil layer,with a lower magnetic susceptibility value.There is no significant difference in pollen characteristics between the flood layer and soil layer,suggesting that the pollen assemblages of flood plain soil and flood sediment can both be used to define the vegetation of the watershed.However,the pollen abundance of flood accumulation layer(7313.96grains/g)is much higher than that of underlying soil layer(1562.65 grains/g).The experimental results suggest that the flood has the function to enrich the sporopollen to certain extent,and the magnetic susceptibility value may reflect the generation and

关 键 词：现代洪水沉积 水动力过程 粒度 孢粉 磁化率 弥河 

分 类 号：P534.63[天文地球—第四纪地质学]