Use of Water Balance and Tracer-Based Approaches to Monitor Groundwater Recharge in the Hyper-Arid Gobi Desert of Northwestern China
Use of Water Balance and Tracer-Based Approaches to Monitor Groundwater Recharge in the Hyper-Arid Gobi Desert of Northwestern China
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DOI：
10.3390/environments5050055
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发表时间：
2018-05-01
期刊：
影响因子：
3.7
通讯作者：
Kharrazi, Ali
中科院分区：
文献类型：
--
作者：
Akiyama, Tomohiro;Kubota, Jumpei;Kharrazi, Ali
采用水量平衡法和示踪法分析了中国西北极端干旱戈壁滩地下水补给机制。2004年4月至8月，对蒸发、土壤水分及其与单次降雨事件的关系进行了研究。还对雨水、地下水和地表水进行了水样采样。在此期间，观测到10次降水事件，总量为41.5毫米，最大降水为28.9毫米。该期间的蒸发量估计为33.1毫米。只有来自最大降水的土壤水分留在了包气带中。这是因为在最强降水事件发生几天后形成的干燥表层阻止了蒸发。在此之前，最大的降水迅速渗透，没有受到蒸发的影响。这一点得到了同位素证据的证实，即最大的降水和地下水都没有留下显著的动力蒸发的痕迹。基于同位素分馏及其质量平衡理论的土壤剩余水分估计值也表明，在入渗过程中没有动力学分馏的痕迹。此外，最大降水的稳定同位素组成与地下水非常相似。因此，我们认为高强度降水是地下水的主要来源，它快速入渗，没有任何蒸发痕迹。
The groundwater recharge mechanism in the hyper-arid Gobi Desert of Northwestern China was analyzed using water balance and tracer-based approaches. Investigations of evaporation, soil water content, and their relationships with individual rainfall events were conducted from April to August of 2004. Water sampling of rainwater, groundwater, and surface water was also conducted. During this period, 10 precipitation events with a total amount of 41.5 mm, including a maximum of 28.9 mm, were observed. Evaporation during the period was estimated to be 33.1 mm. Only the soil water, which was derived from the heaviest precipitation, remained in the vadose zone. This is because a dry surface layer, which was formed several days after the heaviest precipitation event, prevented evaporation. Prior to that, the heaviest precipitation rapidly infiltrated without being affected by evaporation. This is corroborated by the isotopic evidence that both the heaviest precipitation and the groundwater retained no trace of significant kinetic evaporation. Estimated -values of the remaining soil water based on isotopic fractionation and its mass balance theories also demonstrated no trace of kinetic fractionation in the infiltration process. Moreover, stable isotopic compositions of the heaviest precipitation and the groundwater were very similar. Therefore, we concluded that the high-intensity precipitation, which rapidly infiltrated without any trace of evaporation, was the main source of the groundwater.