Tritium profiles of pore water in the Chinese loess unsaturated zone: Implications for estimation of groundwater recharge
Tritium profiles of pore water in the Chinese loess unsaturated zone: Implications for estimation of groundwater recharge
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DOI：
10.1016/j.jhydrol.2005.12.010
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发表时间：
2006-08
影响因子：
6.4
通讯作者：
R. Lin;K. Wei
中科院分区：
文献类型：
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作者：
R. Lin;K. Wei
在IAEA 9402号研究合同的框架内，1997年和1998年分别在内蒙古和山西黄土包气带采集了两个岩心，其中一个测试坑和一个80年代采集的岩心的孔隙水氚剖面已被报道。研究表明，即使在20世纪90年代后期，孔隙水的氚剖面仍然显示出清晰的峰，如以前报道的那样。这是因为两个采样点都位于北方的高纬度地区。这也是由于黄土存款的非常特殊的特性，提供了缓慢的渗透率的孔隙水在非饱和区。从这些氚剖面得到的平均入渗速率为0.30m/a。内蒙古和山西地下水年补给量分别为47和68 mm/a。然而，两个采样点附近地下含水层的氚含量都高于预期。因此，黄土区土壤的垂直入渗可能不是地下水补给的唯一机制。无压含水层也可通过深谷或垂直劈理的地表水流得到补给，垂直劈理通常在黄土存款中形成。因此，在黄土包气带中利用氚剖面得到的地下水补给量可能被低估。
Within the framework of the IAEA research contract No. 9402, two cores were taken in 1997 and 1998 in the loess unsaturated zone in Inner Mongolia and Shanxi province, respectively, where the tritium profiles of pore water from a test pit and a core taken in 1980’s had already been reported. It has been shown that even in the late 1990’s, the tritium profiles of pore water still showed clearly defined peaks, as those formerly reported. This is because both sampling sites were located at rather high latitudes of the Northern Hemisphere. This is also, thanks to the very special characteristics of the loess deposit, providing slow infiltration rate of pore water in the unsaturated zone. Average infiltration rate obtained from these tritium profiles was 0.30m/a. The values of annual groundwater recharge were 47 and 68mm/a for Inner Mongolia and Shanxi province, respectively. However, the tritium content of the groundwater aquifers near both sampling sites was higher than expected. Consequently, it can be concluded that the vertical infiltration in the soils of the semi-arid loess region, perhaps, is not the only mechanism of groundwater recharge. The unconfined aquifers may also be recharged by surface flow through deep valleys, or through vertical cleavages, which are generally developed in the loess deposit. Therefore, the values of groundwater recharge obtained by using tritium profiles in the loess unsaturated zone may be underestimated.