基于氡同位素示踪的洞庭湖区枯水期湖水与地下水交互作用研究  

Interaction between surface water and groundwater during the dry season in Lake Dongting based on 222Rn tracing

作　　者：谌宏伟[1,2,3] 杨瑶 黄荷 周慧 彭向训[1,2,3] 于莎莎 喻娓厚 李正最 王赵国 CHEN Hongwei;YANG Yao;HUANG He;ZHOU Hui;PENG Xiangxun;YU Shasha;YU Weihou;LI Zhengzui;WANG Zhaoguo(School of Hydraulic and Environmental Engineering,Changsha University of Science&Technology,Changsha 410114,China;Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province,Changsha University of Science&Technology,Changsha 410114,China;Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province,Changsha University of Science&Technology,Changsha 410114,China;Hunan Hydrology and Water Resources Survey Center,Changsha 410005,China)

机构地区：[1]长沙理工大学水利与环境工程学院,湖南长沙410114 [2]长沙理工大学水沙科学与水灾害防治湖南省重点实验室,湖南长沙410114 [3]长沙理工大学洞庭湖水环境治理与生态修复湖南省重点实验室,湖南长沙410114 [4]湖南省水文水资源勘测中心,湖南长沙410005

出　　处：《地学前缘》2024年第2期423-434,共12页Earth Science Frontiers

基　　金：湖南省水利科技重大项目(XSKJ2019081-09);湖南省水利一般科技项目(XSKJ2019081-43)。

摘　　要：洞庭湖区水系发达,水文地质条件复杂,人类活动强烈,地表水和地下水的水力联系变化频繁,其研究的难度以及由此造成的研究不足影响了对湖区地下水赋存和运动规律的深入认识。本文以洞庭湖整体为研究对象,采用水位动态分析和氡(222 Rn)同位素示踪法,定性和定量研究枯水期洞庭湖区地表水与地下水的交互作用关系与交互通量。枯水期洞庭湖区水位和氡浓度空间分布特征指示研究区内地下水向湖水排泄,尤以东洞庭湖最为显著。氡箱模型计算结果显示枯水期地下水排泄222 Rn通量为455.09 Bq/(m^(2)·d),占总输入222 Rn通量的60.07%,地下水排泄总量为0.29×10^(8)m^(3)/d,平均排泄速率为56.27 mm/d,地下水排泄对湖水的贡献率为7.04%。敏感性分析表明:风速、地下水和湖水222 Rn浓度以及湖面面积等参数较为敏感,合理布置取样点并提高敏感参数测量准确度能提高模型计算结果的可靠度。氡同位素示踪法物理意义明确、操作过程简便,是研究复杂区域地下水补、径、排特征的有效方法。研究成果一定程度上提供了洞庭湖区水量均衡的更多认识,可为洞庭湖区地下水资源评价和管理提供参考。Lake Tongting area has a dynamic water environment with developed surface water networks,complex hydrogeological conditions and intensive human activities,which makes it difficult to gain in-depth understanding of groundwater storage and movement in the lake area.This study applies dynamic analysis of water levels and radon(222 Rn)tracer method to carry out qualitative and quantitative analyses of surface water-groundwater interaction and exchange fluxes in Lake Tongting area in the dry season.The spatial distribution patterns of water levels and 222 Rn concentrations in the lake area in the dry season(between 20182020)indicated that groundwater(GD)discharge to the lake occurred in the dry season,especially in eastern Lake Dongting.According to calculation using radon box model,the GD-borne 222 Rn flux in the dry season was 455.09 Bq/(m^(2)·d),or 60.07%of total 222 Rn flux to the lake;the total groundwater discharge was 0.29×10^(8)m^(3)/d,and the average discharge rate was 56.27 mm/d.Groundwater discharge contributed to 7.04%of surface water in the dry season.Sensitivity analysis showed that sensitive variables in the model were wind speed,222 Rn concentration in groundwater/lake water and surface area.Improvements of sampling scheme and measurement accuracy of sensitive variables can improve reliability of calculation results.With clear physical significance and simple application protocol,radon(222 Rn)tracer has certain application advantageous that it can be effectively used to quantify groundwater recharge,runoff and discharge in complex water environments.The research results provide better understanding of water balance in Lake Dongting and can serve as reference for water resource evaluation and management in the lake area.

关 键 词：地表水地下水交互作用 水位动态 氡同位素 枯水期 洞庭湖区 

分 类 号：P597[天文地球—地球化学] P641[天文地球—地质学] P343.3