A study of the increase in subsurface freshwater on coral islands by slope seepage control: Experiment and modeling
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摘要:
地下淡水是支撑海岛居民生活用水保障和生态岛屿建设的重要战略资源。目前海岛淡水资源十分匮乏，鉴于我国灰沙岛的现实复杂性，亟需实施低成本、易操作且对岛礁稳定性及生态系统影响较小的增加地下淡水的措施。本研究提出了采用在海陆边坡处铺设防渗材料人为干预地下淡水体形成、增加淡水储量的措施，并通过砂箱试验和数值模拟相结合的方法在实验室尺度下分析了边坡防渗对灰沙岛淡水透镜体形成的影响，评估了不同因素在边坡防渗条件下增加地下淡水储量的效果，并以永兴岛为例定量评估了边坡防渗对地下淡水储量的影响。研究表明，边坡防渗通过改变地下水流场、增加淡水水头的方式增加了淡水储量。淡水体所需的稳定时间随之增加。在长、宽、高分别为50，5，35 cm的砂箱中，在35°的边坡处铺设14 cm长的隔水材料，淡水透镜体达到稳定后最大厚度由原有的13.7 cm增加至24.9 cm，淡水储量由561.8 cm3增加至1592.3 cm3，所需稳定时间由120 min增加至150 min。增加的淡水储量随降雨强度增加、砂体渗透系数减小、边坡防渗深度增加、防渗材料渗透系数减小而增加。若在永兴岛海陆边坡铺设2 m深的隔水材料，在未来30 a，淡水储量将由天然状态的3.4×106 m3增加至4.4×106 m3，增加原有储量的1/4。研究可为我国岛屿地下淡水科学管理、水资源安全保障提供理论支撑和实践指导。
Abstract:Fresh groundwater lenses are important resources for local inhabitants and ecosystems in coral islands. In view of the complexity of the coral islands, it is necessary to seek the measures of low-cost, effective and less impact on the stability and the ecosystem to increase freshwater reserves. Based on the sandbox experiments and numerical simulations, this study proposes an engineering measure to increase freshwater reserves by laying impermeable materials on the slope of an island. The effects of the measure on fresh groundwater lenses formation and different factors on increasing freshwater reserves in slope seepage prevention are evaluated. The practical feasibility of this measure is also discussed in case of the Yongxing Island. The results show that the slope seepage control increases the freshwater reserves by changing the groundwater flow field to increase the freshwater head. The stabilization time of the freshwater lens is also increased. After laying impermeable materials on slope of the sandbox (with the length, width and height of 50 cm, 5 cm and 35 cm, respectively), the maximum thickness of freshwater lens increases from 13.7 cm to 24.9 cm, the freshwater reserves increases from 561.8 cm3 to 1592.3 cm3, and stabilization time increases from 120 min to 150 min, respectively. The increased freshwater reserves develop with the increasing rainfall intensity and slope impermeable depth, and also extend with the decreasing permeability of coral sand and impermeable materials. The Yongxing Island is taken as an example, and laying impermeable materials with a depth of 2 m on the slope will increase the freshwater reserves from 3.4×106 m3 to 4.4×106 m3 in the next 30 years, increasing the original reserve by 1/4. This study can provide theoretical support and practical guidance for sustainable groundwater management and water resources security in island areas of China.
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Key words:
- slope seepage control /
- coral islands /
- freshwater lenses /
- numerical simulations /
- sandbox experiments
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表 2 参数赋值
Table 2. Parameters selection
参数选取 参数赋值 降雨强度/（cm·min−1） 0.2, 0.4, 0.6, 0.8, 1.0 砂体渗透系数/（cm·min−1） 12, 16, 20, 24, 28 边坡防渗长度/cm 2, 5, 8, 11, 14 防渗材料渗透系数/（cm·min−1） 0, 0.5, 1.0, 1.5, 2.0, 2.5 
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[1] 赵焕庭,王丽荣,宋朝景. 南海诸岛灰沙岛淡水透镜体研究述评[J]. 海洋通报,2014,33(6):601 − 610. [ZHAO Huanting,WANG Lirong,SONG Chaojing. Review on freshwater lens of lime-sand island in Nanhai Zhudao[J]. Marine Science Bulletin,2014,33(6):601 − 610. (in Chinese with English abstract)
[2] 赵焕庭,王丽荣. 珊瑚礁岛屿淡水透镜体研究综述[J]. 热带地理,2015,35(1):120 − 129. [ZHAO Huanting,WANG Lirong. Review on the study of freshwater lens in the coral reef island[J]. Tropical Geography,2015,35(1):120 − 129. (in Chinese with English abstract) doi: 10.13284/j.cnki.rddl.002643
[3] 周从直, 方振东, 魏营. 珊瑚岛礁淡水透镜体的开发利用[M]. 重庆: 重庆大学出版社, 2017
ZHOU Congzhi, FANG Zhendong, WEI Ying. Development and utilization of freshwater lens of coral reef[M]. Chongqing: Chongqing University Press, 2017. （in Chinese）
[4] 盛冲,张云帆,李付成,等. 钙质珊瑚砂水理参数测定与涵淡水能力模拟[J]. 河海大学学报(自然科学版),2020,48(6):562 − 568. [SHENG Chong,ZHANG Yunfan,LI Fucheng,et al. Measurement of hydrological parameters of coral sand and freshwater storage capacity simulation[J]. Journal of Hohai University (Natural Sciences),2020,48(6):562 − 568. (in Chinese with English abstract)
[5] WERNER A D,SHARP H K,GALVIS S C,et al. Hydrogeology and management of freshwater lenses on atoll Islands:Review of current knowledge and research needs[J]. Journal of Hydrology,2017,551:819 − 844. doi: 10.1016/j.jhydrol.2017.02.047
[6] WHITE I,FALKLAND T. Management of freshwater lenses on small Pacific Islands[J]. Hydrogeology Journal,2010,18(1):227 − 246. doi: 10.1007/s10040-009-0525-0
[7] 韩冬梅,曹国亮,宋献方. 南海珊瑚礁人工岛淡水透镜体形成过程及影响因素[J]. 地理学报,2020,75(5):1053 − 1064. [HAN Dongmei,CAO Guoliang,SONG Xianfang. Formation processes and influencing factors of freshwater lens in artificial island of coral reef in South China Sea[J]. Acta Geographica Sinica,2020,75(5):1053 − 1064. (in Chinese with English abstract) doi: 10.11821/dlxb202005012
[8] BRYAN E,MEREDITH K T,BAKER A,et al. Island groundwater resources,impacts of abstraction and a drying climate:Rottnest Island,Western Australia[J]. Journal of Hydrology,2016,542:704 − 718. doi: 10.1016/j.jhydrol.2016.09.043
[9] POST V E A,HOUBEN G J. Density-driven vertical transport of saltwater through the freshwater lens on the island of Baltrum (Germany) following the 1962 storm flood[J]. Journal of Hydrology,2017,551:689 − 702. doi: 10.1016/j.jhydrol.2017.02.007
[10] 周从直, 方振东, 官举德, 等. 珊瑚岛礁淡水透镜体的模拟与开发利用[J]. 杭州应用工程技术学院学报, 1999, 11（增刊1）: 16 − 20
ZHOU Congzhi, FANG Zhendong, GUAN Jude, et al. Numerical simulation and development of the freshwater lens on a coral island[J]. Journal of Hangzhou Institute of Applied Engineeking, 1999, 11（Sup 1）: 16 − 20. （in Chinese with English abstract）
[11] 周从直,方振东,梁恒国,等. 珊瑚岛礁淡水透镜体的数值模[J]. 海洋科学,2004,28(11):77 − 80. [ZHOU Congzhi,FANG Zhendong,LIANG Hengguo,et al. Numerical simulation of freshwater lens on coral island[J]. Marine Sciences,2004,28(11):77 − 80. (in Chinese with English abstract) doi: 10.3969/j.issn.1000-3096.2004.11.017
[12] 周从直,方振东,梁恒国,等. 雨量变化对珊瑚岛礁淡水透镜体的影响[J]. 中国给水排水,2006,22(1):53 − 57. [ZHOU Congzhi,FANG Zhendong,LIANG Hengguo,et al. Influence of rainfall on freshwater lens in a coral island[J]. China Water & Wastewater,2006,22(1):53 − 57. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-4602.2006.01.013
[13] 甄黎,周从直,束龙仓,等. 海岛淡水透镜体演变规律的室内模拟实验[J]. 吉林大学学报(地球科学版),2008,38(1):81 − 85. [ZHEN Li,ZHOU Congzhi,SHU Longcang,et al. Laboratory simulation experiment of evolution of island freshwater lens[J]. Journal of Jilin University (Earth Science Edition),2008,38(1):81 − 85. (in Chinese with English abstract)
[14] 赵军,温忠辉,束龙仓,等. 海岛淡水透镜体形成及倒锥演变规律分析[J]. 工程勘察,2009,37(5):40 − 44. [ZHAO Jun,WEN Zhonghui,SHU Longcang,et al. Formation of freshwater lens in islands and evolution rules of the upconing[J]. Geotechnical Investigation & Surveying,2009,37(5):40 − 44. (in Chinese with English abstract)
[15] 周从直,谯华,杜蓉. 珊瑚岛淡水透镜体的模拟与开发[J]. 后勤工程学院学报,2016,32(3):1 − 10. [ZHOU Congzhi,QIAO Hua,DU Rong. Simulation and exploitation of the freshwater lens in coral island[J]. Journal of Logistical Engineering University,2016,32(3):1 − 10. (in Chinese with English abstract) doi: 10.3969/j.issn.1672-7843.2016.03.001
[16] HERNDON R,MARKUS M. Large-scale aquifer replenishment and seawater intrusion control using recycled water in Southern California[J]. Boletín Geológico y Minero,2014,125(2):143 − 55.
[17] BOUWER H. Artificial recharge of groundwater:Hydrogeology and engineering[J]. Hydrogeology Journal,2002,10(1):121 − 142. doi: 10.1007/s10040-001-0182-4
[18] POST V E A,GALVIS S C,SINCLAIR P J,et al. Evaluation of management scenarios for potable water supply using script-based numerical groundwater models of a freshwater lens[J]. Journal of Hydrology,2019,571:843 − 855. doi: 10.1016/j.jhydrol.2019.02.024
[19] 盛冲,许鹤华,张文涛. 地貌变化对永兴岛淡水透镜体影响的数值模拟[J]. 水文地质工程地质,2018,45(6):7 − 14. [SHENG Chong,XU Hehua,ZHANG Wentao. Numerical simulation of the effect of geomorphologic changes on freshwater lens in the Yongxing Island[J]. Hydrogeology & Engineering Geology,2018,45(6):7 − 14. (in Chinese with English abstract) doi: 10.16030/j.cnki.issn.1000-3665.2018.06.02
[20] SHENG Chong,JIAO J J,XU Hehua,et al. Influence of land reclamation on fresh groundwater lenses in oceanic Islands:Laboratory and numerical validation[J]. Water Resources Research,2021,57(10):e2021WR030238.
[21] LU Chunhui,CAO Hongfan,MA Jing,et al. A proof-of-concept study of using a less permeable slice along the shoreline to increase fresh groundwater storage of oceanic Islands:Analytical and experimental validation[J]. Water Resources Research,2019,55(8):6450 − 6463. doi: 10.1029/2018WR024529
[22] 马婧,鲁春辉,吴吉春,等. 一种可增加海岛地下淡水资源储量的方法研究[J]. 水文地质工程地质,2020,47(3):1 − 7. [MA Jing,LU Chunhui,WU Jichun,et al. A method for improving the fresh groundwater storage of oceanic Islands[J]. Hydrogeology & Engineering Geology,2020,47(3):1 − 7. (in Chinese with English abstract) doi: 10.16030/j.cnki.issn.1000-3665.201909048
[23] 赵焕庭,王丽荣,宋朝景. 南海珊瑚礁地貌模型研究[J]. 海洋学报,2014,36(9):112 − 120. [ZHAO Huanting,WANG Lirong,SONG Chaojing. Geomorphological model of coral reefs in the South China Sea[J]. Acta Oceanologica Sinica,2014,36(9):112 − 120. (in Chinese with English abstract)
[24] STOECKL L,HOUBEN G. Flow dynamics and age stratification of freshwater lenses:Experiments and modeling[J]. Journal of Hydrology,2012,458/459:9 − 15. doi: 10.1016/j.jhydrol.2012.05.070
[25] DOSE E J,STOECKL L,HOUBEN G J,et al. Experiments and modeling of freshwater lenses in layered aquifers:Steady state interface geometry[J]. Journal of Hydrology,2014,509:621 − 630. doi: 10.1016/j.jhydrol.2013.10.010
[26] 薛禹群, 谢春红, 吴吉春, 等. 海水入侵咸淡水界面运移规律研究[M]. 南京: 南京大学出版社, 1991
XUE Yuqun. XIE Chunhong, WU Jichun, et al. Study on migration law of salt-fresh water interface[M]. Nanjing: Nanjing University Press, 1991. （in Chinese）
[27] 周从直,何丽,杨琴,等. 珊瑚岛礁淡水透镜体三维数值模拟研究[J]. 水利学报,2010,41(5):560 − 566. [ZHOU Congzhi,HE Li,YANG Qin,et al. Three-dimensional numerical simulation of freshwater len in coral Islands[J]. Journal of Hydraulic Engineering,2010,41(5):560 − 566. (in Chinese with English abstract) doi: 10.13243/j.cnki.slxb.2010.05.001
[28] ABDOULHALIK A,AHMED A A. The effectiveness of cutoff walls to control saltwater intrusion in multi-layered coastal aquifers:Experimental and numerical study[J]. Journal of Environmental Management,2017,199:62 − 73.
[29] LUYUN R J,MOMII K,NAKAGAWA K. Effects of recharge wells and flow barriers on seawater intrusion[J]. Ground Water,2011,49(2):239 − 249. doi: 10.1111/j.1745-6584.2010.00719.x
[30] 沈建伟,杨红强,王月,等. 西沙永兴岛珊瑚礁坪的群落动态和浅水碳酸盐沉积特征[J]. 中国科学:地球科学,2014,44(3):472 − 487. [SHEN Jianwei,YANG Hongqiang,WANG Yue,et al. Community dynamics and shallow water carbonate deposition characteristics of coral reef flat in Yongxing Island[J]. Scientia Sinica (Terrae),2014,44(3):472 − 487. (in Chinese with English abstract) doi: 10.1360/zd-2014-44-3-472
[31] VACHER H L. Dupuit-Ghyben-Herzberg analysis of strip-island lenses[J]. Geological Society of America Bulletin,1988,100(4):580 − 591. doi: 10.1130/0016-7606(1988)100<0580:DGHAOS>2.3.CO;2
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