Estimation of seawater–groundwater exchange rate: case study in a tidal flat with a large-scale seepage face (Laizhou Bay, China)
Estimation of seawater–groundwater exchange rate: case study in a tidal flat with a large-scale seepage face (Laizhou Bay, China)
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DOI：
10.1007/s10040-014-1196-z
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发表时间：
2015-03
影响因子：
2.8
通讯作者：
Q. Ma;Hailong Li;Xuejing Wang;Chaoyue Wang;L. Wan;Xu-sheng Wang;Xiaowei Jiang
中科院分区：
文献类型：
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作者：
Q. Ma;Hailong Li;Xuejing Wang;Chaoyue Wang;L. Wan;Xu-sheng Wang;Xiaowei Jiang
莱州湾滩涂海水与地下水交换率研究考虑到渗流面和密度的影响，基于地下水头、温度和盐度的现场测量，提出了一种简单有效的估算海水-地下水交换率的方法。首先，利用广义达西定律获得每口井的汇率，然后将结果沿整个断面进行插值和积分。海底地下水总排放量 (SGD) 和流入量估计分别为 8.8 和 15.3 m3d−1m−1。 SGD和流入量的空间分布与沙滩或砾石滩不同，可能是由于低渗透沉积物（粉砂和泥）、非常平缓的坡度和大范围的渗流面。在低潮线附近发现了一条淡水排放管，那里观察到的地下水流出量显着增加且盐度较低，就证明了这一点。渗流面的 SGD 占总 SGD 的 ∼21%。渗流面流出量、渗流面流出量占总流出量的比例均向海方向显着单调下降。
The exchange rate between seawater and groundwater in a tidal flat was investigated at Laizhou Bay, China, where there are large-scale seepage faces with horizontal extension of several hundred meters developed during low tides. Taking into account the effects of seepage face and density, a simple and efficient method for estimating seawater–groundwater exchange rate is proposed, based on field measurements of groundwater hydraulic head, temperature and salinity. First, the exchange rate at each well was obtained using the generalized Darcy’s law, then the results were interpolated and integrated along the whole transect. The total submarine groundwater discharge (SGD) and inflow were estimated to be 8.8 and 15.3 m3d−1m−1, respectively. The spatial distributions of SGD and inflow were different from those of sandy or gravel beaches possibly owing to the low-permeability sediment (silty sand with mud), very gentle slope, and the large-scale seepage faces. A freshwater discharge tube was identified near the low-tide line, as evidenced by significant increase in outflow and low salinity of groundwater observed there. The SGD from the seepage faces accounted for ∼21 % of the total SGD. The outflow rate that occurred from the seepage faces, and the ratio of the outflow from the seepage faces to the total outflow, decreased seaward significantly and monotonically.