基于盐度动态模拟估算潮间带地下淡水排泄量  

Submarine fresh groundwater discharge estimation in the intertidal zone based on dynamic salinity simulation

作　　者：王志秀 李亚松 郝奇琛[1,2] 张媛静 肖勇[4] 刘春雷 WANG Zhixiu;LI Yasong;HAO Qichen;ZHANG Yuanjing;XIAO Yong;LIU Chunlei(Fujian Provincial Key Laboratory of Water Cycling and Eco-Geological Processes,Xiamen,Fujian 361021,China;Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang,Hebei 050061,China;College of Urban Geology and Engineering,Hebei GEO University,Shijiazhuang,Hebei 050031,China;Faculty of Geosciences and Engineering,Southwest Jiaotong University,Chengdu,Sichuan 611756,China)

机构地区：[1]福建省水循环与生态地质过程重点实验室,福建厦门361021 [2]中国地质科学院水文地质环境地质研究所,河北石家庄050061 [3]河北地质大学城市地质与工程学院,河北石家庄050031 [4]西南交通大学地球科学与工程学院,四川成都611756

出　　处：《水文地质工程地质》2024年第5期56-67,共12页Hydrogeology & Engineering Geology

基　　金：国家重点研发计划项目(2022YFF1301301);厦门自然科学基金项目(3502Z202373152);福建省水循环与生态地质过程重点实验室开放基金项目(SK202305KF01);水环所基本科研业务费项目(SK202305);中国地质调查局地质调查项目(DD20190303,DD20230459)。

摘　　要：目前关于砂质潮间带海底地下淡水排泄速率、海水再循环速率及相应比例随潮位的变化研究较少。文章以厦门湾某砂质潮滩为例,对地下水渗出面的盐度进行实地动态监测,采用变密度流数值模拟技术,对潮间带地下水盐度变化过程进行动态模拟,以此反演潮间带海底地下淡水排泄量。研究结果显示:(1)潮间带不同位置地下水盐度随潮汐发生不同规律的变化,通过数值模型估算出典型剖面海底地下水排泄量为17.47 m^(3)/(m·d),其中海底地下淡水排泄量为3.19 m^(3)/(m·d),占海底地下水排泄总量的18.26%,海水再循环量为14.28 m^(3)/(m·d),占海底地下水排泄总量的81.74%,处于主导地位;(2)潮汐作用下,海水入渗与海底地下水排泄交替发生,落潮阶段发生交替的时间略早于平潮位,涨潮阶段发生交替的时间略晚于平潮位,海水入渗速率与海底地下水排泄速率达到峰值时刻分别早于潮位达到高潮和低潮时刻,整个潮汐周期内(从高潮时刻到下一个高潮时刻)海底地下淡水排泄量比例逐渐增大;(3)潮间带地下水盐度的变化可间接反映海底地下淡水排泄量的变化,与其他研究相比,该典型剖面的海底地下淡水排泄量占海底地下水排泄总量比例相对较高,显示潮间带存在着大量海底地下淡水排泄;(4)通过敏感性分析可知,内陆水头对海底地下淡水排泄量及盐度空间分布有重要影响。研究可为海岸带地下水开发利用和滨海环境管理提供一定参考。Currently,limited studies focused on the variations in submarine fresh groundwater discharge rates,seawater recirculation rates,and their respective proportions with tidal level change in sandy intertidal zones.This study conducted in-situ dynamic monitoring of the salinity at the groundwater seepage face in a sandy tidal flat in Xiamen Bay.Using variable-density flow numerical model,the dynamic groundwater salinity in the intertidal zone was simulated to calculate the submarine fresh groundwater discharge in the intertidal zone.The results show that groundwater salinity at different locations in the intertidal zone exhibits varying patterns with the tides.The submarine groundwater discharge at a typical profile was estimated to be 17.47 m^(3)/(m·d),in which the submarine fresh groundwater discharge was calculated to be 3.19 m^(3)/(m·d),accounting for 18.26%of the total submarine groundwater discharge.In contrast,recirculated submarine groundwater discharge was estimated to be 14.28 m^(3)/(m·d),constituting 81.74%of the total submarine groundwater discharge and thus playing a dominant role.Under the influence of tides,seawater infiltration and submarine groundwater discharge are alternate.The alternation during ebb tide occurs slightly earlier than the slack water level,while during flood tide,it occurs slightly later.The peak moment of seawater infiltration rate and submarine groundwater discharge rate precede the tidal peaks at high and low tides,respectively.Throughout the tidal cycle(from high tide to the next high tide),the proportion of submarine fresh groundwater discharge gradually increases.The variation in groundwater salinity in the intertidal zone can represent the changes in submarine fresh groundwater discharge.The proportion of submarine fresh groundwater discharge in the total submarine groundwater discharge is relatively high in this typical profile than that in the previous studies.It indicates the presence of a substantial amount of submarine fresh groundwater discharge in the intertidal zon

关 键 词：海岸带 海底地下淡水排泄 数值模拟 地下水盐度 砂质海岸 渗出面 

分 类 号：P641.8[天文地球—地质矿产勘探]