南海珊瑚礁人工岛淡水透镜体形成过程及影响因素

doi:10.11821/dlxb202005012

摘要/Abstract

摘要：

中国目前在珊瑚礁上建设人工岛的目标是建成生态宜居岛屿,人工岛地下海水在降雨入渗驱替作用下逐渐淡化,形成的淡水透镜体是支撑岛屿生态系统的重要水源。本文针对南海珊瑚礁普遍存在的上土下岩的二元地质结构,考虑不同测量方法得到的南海人工岛填筑所用珊瑚砂渗透系数存在较大差异,建立了珊瑚礁人工岛淡水驱替海水形成淡水透镜体的动态模拟模型,对南海某珊瑚礁人工岛开展了系列数值模拟研究。结果表明,人工岛礁二元地质结构不同的渗透性对人工岛淡水开始形成时间无明显影响,填岛完成2年左右的时间可观测到淡水,估计（或理论计算）在10~20年内可形成相对稳定的淡水透镜体;在人工岛面积达到一定规模的前提下,全新世珊瑚砂沉积物渗透性是控制人工岛礁淡水透镜体的主要因素,能够形成的淡水透镜体体积随渗透系数增大而呈对数减小,并且淡水透镜体体积随全新世沉积物渗透性增大而减小的速率较淡水透镜体厚度更加显著;淡水透镜体越过不整合面进入更新世礁灰岩后,由于含水层渗透系数突然增大,淡水透镜体向水平方向扩展,在礁灰岩顶界形成“髭”状淡水体。

关键词: 人工岛礁, 二元地质结构, 淡水透镜体, 珊瑚砂渗透性, 南海

Abstract:

The goal of constructing artificial islands on coral reefs in China is to build ecological habitable islands. The seawater in the artificial islands is gradually replaced by rainfall infiltration, and the freshwater lens formed is an important water source supporting the island ecosystem. The double-layer geological structure is widespread in coral reefs in the South China Sea. Considering the fact that there exists a great large difference in the permeability coefficients obtained using different measurement methods, this study established numerical simulation models for a coral reef island in the South China Sea to simulate the seawater refreshing process. The results show that different permeabilities of the double-layer geological structure of the artificial islands have no obvious influence on the formation time of fresh water on the artificial islands. The permeability of the Holocene coral sand sediment is the main factor controlling the freshwater lens of the artificial reef. The volume of the forming freshwater lens decreases logarithmically with the increase of the permeability coefficient, and the volume of the freshwater lens decreases more significantly with the increase of the permeability of the Holocene sediment than the thickness of the freshwater lens. After the freshwater lens crossed the unconformity surface and entered the Pleistocene reef limestone, due to the sudden increase of the permeability coefficient of the aquifer, the freshwater lens expanded to the horizontal direction and formed the mustached-shape freshwater body in the reef limestone.

Key words: artificial island, double-layer geological structure, freshwater lens, coral sand permeability, South China Sea

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.

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参考文献 43

[1]	Zhao Huanting, Wang Lirong . Construction of artificial islands on coral reef in the South China Sea Islands. Tropical Geography, 2017,37(5):681-693. doi: 10.13284/j.cnki.rddl.002974
	[ 赵焕庭, 王丽荣 . 南海诸岛珊瑚礁人工岛建造研究. 热带地理, 2017,37(5):681-693.] doi: 10.13284/j.cnki.rddl.002974
[2]	Zhao Huanting, Wang Lirong, Song Chaojing . Geomorphological model of coral reefs in the South China Sea. Acta Oceanologica Sinica, 2014,36(9):112-120. doi: 10.3969.issn.0253-4193.2014.09.013
	[ 赵焕庭, 王丽荣, 宋朝景 . 南海珊瑚礁地貌模型研究. 海洋学报, 2014,36(9):112-120.] doi: 10.3969.issn.0253-4193.2014.09.013
[3]	Zhao Huanting, Wang Lirong . Review on the study of freshwater lens in the coral reef island. Tropical Geography, 2015,35(1):120-129.
	[ 赵焕庭, 王丽荣 . 珊瑚礁岛屿淡水透镜体研究综述. 热带地理, 2015,35(1):120-129.]
[4]	Zhao Huanting, Wang Lirong, Song Chaojing . Review on freshwater lens of lime-sand island in Nanhai Zhudao. Marine Science Bulletin, 2014,33(6):601-610.
	[ 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. 海洋通报, 2014,33(6):601-610.]
[5]	Cao Yingjie . Numerical simulation of the formation and evolution of freshwater lens in islands[D]. Nanjing: Hohai University, 2008.
	[ 曹英杰 . 海岛淡水透镜体形成和演化规律的数值模拟研究[D]. 南京: 河海大学, 2008.]
[6]	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. Journal of Hydrology, 2017,551:819-844. doi: 10.1016/j.jhydrol.2017.02.047
[7]	Zhou Congzhi, He Li, Yang Qin , et al. Three-dimensional numerical simulation of freshwater len in coral islands. Journal of Hydraulic Engineering, 2010,41(5):560-566.
	[ 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. 水利学报, 2010,41(5):560-566.]
[8]	Fang Zhendong, Zhou Congzhi, Liang Hengguo , et al. Research on influential factors upon the up-cone of the freshwater lens in a coral island. Journal of Logistical Engineering University, 2012,28(4):57-66.
	[ 方振东, 周从直, 梁恒国 , 等. 珊瑚岛淡水透镜体抽水倒锥影响因素研究. 后勤工程学院学报, 2012,28(4):57-66.]
[9]	Zhou Congzhi, Fang Zhendong, Liang Henguo , et al. Influence of rainfall on freshwater lens in a coral island. China Water & Wastewater, 2006,22(1):53-57.
	[ 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. 中国给水排水, 2006,22(1):53-57.]
[10]	Sheng Chong, Xu Hehua, Zhang Wentao . Numerical simulation of the effect of geomorphologic changes on freshwater lens in the Yongxing Island. Hydrogeology and Engineering Geology, 2018,45(6):7-14.
	[ 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. 水文地质工程地质, 2018,45(6):7-14.]
[11]	Zhen Li . Physical simulation of formation and evolution of freshwater lens in island[D]. Nanjing: Hohai University, 2008.
	[ 甄黎 . 海岛淡水透镜体形成与演化规律的物理模拟[D]. 南京: 河海大学, 2008.]
[12]	Li Daning, Xu Jiexin, Zhao Hui , et al. Temporal variations and influencing factors of freshwater lens in Yongxing Island. Journal of Guangdong Ocean University, 2019,39(2):67-74.
	[ 黎大宁, 许洁馨, 赵辉 , 等. 永兴岛淡水透镜体的时间变化规律及其影响因素. 广东海洋大学学报, 2019,39(2):67-74.]
[13]	Zhao Jun . Analysis on the evolution law of freshwater lens in island under mining condition[D]. Nanjing: Hohai University, 2007.
	[ 赵军 . 开采条件下海岛淡水透镜体演变规律分析[D]. 南京: 河海大学, 2007.]
[14]	Zhou Congzhi, Qiao Hua, Du Rong . Simulation and exploitation of the freshwater lens in coral island. Journal of Logistical Engineering University, 2016,32(3):1-10.
	[ 周从直, 谯华, 杜蓉 . 珊瑚岛淡水透镜体的模拟与开发. 后勤工程学院学报, 2016,32(3):1-10.]
[15]	Zhou Congzhi, Fang Zhendong, Liang Hengguo , et al. Numerical simulation of freshwater lens on coral island. Marine Sciences, 2004,28(11):77-80.
	[ 周从直, 方振东, 梁恒国 , 等. 珊瑚岛礁淡水透镜体的数值模拟. 海洋科学, 2004,28(11):77-80.]
[16]	Zhou Congzhi, Fang Zhendong, Wei Ying , et al. Development and Utilization of Freshwater Lenses on Coral Reefs. Chongqing: Chongqing University Press, 2017.
	[ 周从直, 方振东, 魏营 , 等. 珊瑚岛礁淡水透镜体的开发利用. 重庆: 重庆大学出版社, 2017.]
[17]	Hu Mingjian, Cui Xiang, Wang Xinzhi , et al. Experimental study on the effect of fine particles on permeability of the calcareous sand. Rock and Soil Mechanics, 2019,40(8):1-6.
	[ 胡明鉴, 崔翔, 王新志 , 等. 细颗粒对钙质砂渗透性的影响试验研究. 岩土力学, 2019,40(8):1-6.]
[18]	Zhao Xiaowei . Experimental study on the effect of freshwater seawater mixing on the distribution and permeability of coral sand [D]. Beijing: China University of Geosciences (Beijing), 2018.
	[ 赵孝伟 . 咸淡水混合对珊瑚砂溶蚀及渗透特性影响试验研究[D]. 北京: 中国地质大学(北京), 2018.]
[19]	Ren Yubin, Wang Yin, Yang Qing . Effects of particle size distribution and shape on permeability of calcareous sand. Rock and Soil Mechanics, 2018,39(2):491-497.
	[ 任玉宾, 王胤, 杨庆 . 颗粒级配与形状对钙质砂渗透性的影响. 岩土力学, 2018,39(2):491-497.]
[20]	Jiang Hanghai . Study on the permeability and characteristics of the groundwater quality of corel reef[D]. Nanning: Guangxi Univeristy, 2018.
	[ 蒋航海 . 珊瑚礁砂渗透性与地下水质变化特征研究[D]. 南宁: 广西大学, 2018.]
[21]	Hu Mingjian, Jiang Hanghai, Zhu Zhangqi , et al. Discussion on permeability of calcareous sand and its influencing factors. Rock and Soil Mechanics, 2017,38(10):2895-2900.
	[ 胡明鉴, 蒋航海, 朱长歧 , 等. 钙质砂的渗透特性及其影响因素探讨. 岩土力学, 2017,38(10):2895-2900.]
[22]	Qian Kun, Wang Xinzhi, Chen Jianwen , et al. Experimental study on permeability of calcareous sand for islands in the South China Sea. Rock and Soil Mechanics, 2017,38(6):1557-1564, 1572.
	[ 钱琨, 王新志, 陈剑文 , 等. 南海岛礁吹填钙质砂渗透特性试验研究. 岩土力学, 2017,38(6):1557-1564, 1572.]
[23]	Ren Yubin . Experimental study on the permeability characteristics of calcareous sand in South China Sea[D]. Dalian: Dalian University of Technology, 2016.
	[ 任玉宾 . 南海钙质砂渗透特性试验研究[D]. 大连: 大连理工大学, 2016.]
[24]	Ou Yixi, Fang Xiangwei, Zhang Nan , et al. Influence of solution salinity on microbial biocementation of coral sand. Journal of Logistical Engineering University, 2016,32(1):78-82.
	[ 欧益希, 方祥位, 张楠 , 等. 溶液盐度对微生物固化珊瑚砂的影响. 后勤工程学院学报, 2016,32(1):78-82.]
[25]	Ou Yixi, Fang Xiangwei, Shen Chunni , et al. Influence of particle sizes of coral sand on biocementation. Journal of Water Resources and Architectural Engineering, 2016,14(2):35-39.
	[ 欧益希, 方祥位, 申春妮 , 等. 颗粒粒径对微生物固化珊瑚砂的影响. 水利与建筑工程学报, 2016,14(2):35-39.]
[26]	Underwood M R, Peterson F L, Voss C I . Groundwater lens dynamics of atoll islands. Water Resources Research, 1992,28(11):2889-2902. doi: 10.1029/92WR01723
[27]	Zhao Huanting, Yuan Jiayi . The landscape and regional palaeogeography of Nansha Islands. Acta Geographica Sinica, 1995,50(2):107-117.
	[ 赵焕庭, 袁家义 . 南沙群岛景观及区域古地理. 地理学报, 1995,50(2):107-117.]
[28]	Ceng Zhaoxuan . Types of atolls in China. Marine Science Bulletin, 1982,4(4):43-50.
	[ 曾昭璇 . 中国环礁的类型划分. 海洋通报, 1982,4(4):43-50.]
[29]	Zhao Liang, Zhang Zhengsheng, Nan Wenlong . Zeng Zhaoxuan's contributions to the geographical research of the South China Sea. Acta Geographica Sinica, 2016,71(3):515-523. doi: 10.11821/dlxb201603013
	[ 赵亮, 张争胜, 南文龙 . 曾昭璇先生对南海地理研究的重要贡献. 地理学报, 2016,71(3):515-523.] doi: 10.11821/dlxb201603013
[30]	Yu Hongbing, Sun Zongxun, Mao Qingwen . Geomorphic features of upper seaward slope of Yongshu Reef, Nansha Islands. Marine Science Bulletin, 1999,18(3):49-54.
	[ 于红兵, 孙宗勋, 毛庆文 . 南沙群岛永暑礁上部向海坡地貌特征研究. 海洋通报, 1999,18(3):49-54.]
[31]	Sun Zongxun, Zhan Wenhuan, Zhu Junjiang . Rockmass stability of Yongshu Reef, Nansha Islands. Marine Geology & Quaternary Geology, 2003,23(4):9-14.
	[ 孙宗勋, 詹文欢, 朱俊江 . 南沙群岛永暑礁岩体稳定性评价. 海洋地质与第四纪地质, 2003,23(4):9-14.]
[32]	Liu Jingru, Wang Jianping, Guo Dong , et al. Three-dimensional morphology and stratigraphic structure of coral reef in Xisha and Nasha Islands. Advances in Geosciences, 2019,9(2):61-68. doi: 10.12677/AG.2019.92008
	[ 刘景儒, 王建平, 郭东 , 等. 西南沙珊瑚礁三维形态和地层结构特征研究. 地球科学前沿, 2019,9(2):61-68.] doi: 10.12677/AG.2019.92008
[33]	Tang Guoyi, Zheng Jianguo . Engineering properties of reef calcareous rock in Southeast Asia. Geotechnical Investigation & Surveying, 2015,43(6):6-10.
	[ 唐国艺, 郑建国 . 东南亚礁灰岩的工程特性. 工程勘察, 2015,43(6):6-10.]
[34]	Zhao Huanting, Zhu Yuanzhi, Nie Baofu , et al. Preliminary division of geological age and Quaternary strata of Yongshu reef. Chinese Science Bulletin, 1992,37(23):2165-2168.
	[ 赵焕庭, 朱袁智, 聂宝符 , 等. 永暑礁地质年代和第四纪地层初步划分. 科学通报, 1992,37(23):2165-2168.]
[35]	Wang Xinzhi, Wang Xing, Hu Mingjian , et al. Study of permeability of calcareous silty layer of foundation at an artificial reclamation island. Rock and Soil Mechanics, 2017,38(11):3127-3135.
	[ 王新志, 王星, 胡明鉴 , 等. 吹填人工岛地基钙质粉土夹层的渗透特性研究. 岩土力学, 2017,38(11):3127-3135.]
[36]	Sun Zongxun, Zhan Wenhuan, Zhu Junjiang . Rockmass structure and engineering geological zones of coral reefs, Nansha Islands of South China Sea. Journal of Tropical Oceanography, 2004,23(3):11-20.
	[ 孙宗勋, 詹文欢, 朱俊江 . 南沙群岛珊瑚礁岩体结构特征及工程地质分带. 热带海洋学报, 2004,23(3):11-20.]
[37]	Post V E A, Bosserelle A L, Galvis S C , et al. On the resilience of small-island freshwater lenses: Evidence of the long-term impacts of groundwater abstraction on Bonriki Island, Kiribati. Journal of Hydrology, 2018,564:133-148. doi: 10.1016/j.jhydrol.2018.06.015
[38]	Sun Zongxun . Engineering properties of coral sands in Nansha Islands. Tropic Oceanology, 2000,19(2):1-8.
	[ 孙宗勋 . 南沙群岛珊瑚砂工程性质研究. 热带海洋, 2000,19(2):1-8.]
[39]	Shu Longcang, Zhou Congzhi, Zhen Li , et al. Measurement of the hydrological properties of coral sand in a laboratory. Journal of Hohai University (Natural Sciences), 2008,36(3):330-332.
	[ 束龙仓, 周从直, 甄黎 , 等. 珊瑚砂含水介质水理性质的实验室测定. 河海大学学报(自然科学版), 2008,36(3):330-332.]
[40]	Hou Lianhua, Wu Xiling, Lin Chengyan , et al. Determination of permeability in ecologic reef reservoir. Acta Petrolei Sincia, 2003,24(5):67-70, 73.
	[ 侯连华, 吴锡令, 林承焰 , 等. 礁灰岩储层渗透率确定方法. 石油学报, 2003,24(5):67-70, 73.]
[41]	Terry J P, Falkland A C . Responses of atoll freshwater lenses to storm-surge overwash in the Northern Cook Islands. Hydrogeology Journal, 2010,18(3):749-759. doi: 10.1007/s10040-009-0544-x
[42]	Bailey R T . Quantifying transient post-overwash aquifer recovery for atoll islands in the western Pacific. Hydrological Processes, 2015,29(20):4470-4482. doi: 10.1002/hyp.v29.20
[43]	Stoeckl L, Houben G J, Dose E J . Experiments and modeling of flow processes in freshwater lenses in layered island aquifers: Analysis of age stratification, travel times and interface propagation. Journal of Hydrology, 2015,529(6851):159-168. doi: 10.1016/j.jhydrol.2015.07.019

测定方法		试样个数/实验组数	渗透系数范围(m/d)	渗透系数平均值(m/d)	数据来源
室内实验	常水头渗透实验	7	535.3~1334.1	706.6	[39]
	常水头渗透实验	5	0.3~1.5	0.9	[22]
	常水头渗透实验	1		1023.8	[19]
	常水头渗透实验	1		58.6	[17]
原位实验	双环渗透实验	12	1.0~52.0		[21]
	多孔稳定流抽水实验	3	0.7~1.6	1.1	[20]
	多孔稳定流抽水实验	4	103.1~114.4	110.0	[16]

全新世珊瑚砂渗透系数(KHH)(m/d)	更新世礁灰岩渗透系数(KHP)为500 m/d			更新世礁灰岩渗透系数(KHP)为1000 m/d
全新世珊瑚砂渗透系数(KHH)(m/d)	淡水透镜体开始形成时间(a)	淡水透镜体最大厚度(m)	淡水透镜体体积(万m³)	淡水透镜体开始形成时间(a)	淡水透镜体最大厚度(m)	淡水透镜体体积(万m³)
5	1.64	22.5	4774.75	1.72	19.5	4463.25
10	1.47	22.5	3969.25	1.84	20.5	3103.5
20	1.7	20.5	2850.25	1.75	19.5	2670.75
30	1.54	21.5	2492.25	1.64	19.5	2378.75
40	1.52	20.5	2257.25	1.53	19.5	2134
50	1.51	20.5	2081.5	1.53	18.5	1964.5
60	1.51	20.5	1963	1.52	18.5	1829.75
70	1.47	19.5	1835.5	1.48	18.5	1769.75
80	1.49	19.5	1715.25	1.49	19.5	1699.75
90	1.46	18.5	1599	1.46	18.5	1587.75
100	1.43	17.5	1502.25	1.43	17.5	1487.25
150	1.44	14.5	1148.75	1.43	14.5	1137.75
200	1.42	12.5	958	1.45	12.5	945.75
300	1.43	8.5	633.5	1.4	7.5	554.75
400	1.43	6.5	387.75	1.43	6.5	389.25
500	1.45	4.5	194.5	1.42	5.5	179.5