3D mapping, hydrodynamics and modelling of the freshwater-brine mixing zone in salt flats similar to the Salar de Atacama (Chile)
3D mapping, hydrodynamics and modelling of the freshwater-brine mixing zone in salt flats similar to the Salar de Atacama (Chile)
复制标题
类似于阿塔卡马盐沼（智利）的盐滩淡水-盐水混合区的 3D 测绘、流体动力学和建模
DOI：
10.1016/j.jhydrol.2018.04.010
复制
发表时间：
2018
影响因子：
6.4
通讯作者：
C. Ayora
中科院分区：
文献类型：
--
作者：
M. A. Marazuela;E. Vázquez;E. Custodio;T. Palma;A. García;C. Ayora
盐滩卤水是矿物质的主要来源，特别是锂。此外，盐滩边缘还普遍存在生态脆弱的宝贵湿地。因此，有效和可持续地开采其中所含的盐水需要对该系统的水文地质学有详细的了解。一个关键的问题是淡水-盐水混合区，这是由于再充淡水和蒸发的盐水之间的质量平衡而形成的。盐滩中发生的复杂过程需要三维（3D）方法来评估混合区的几何形状。在这项研究中，在盐坪的混合区的3D地图，使用Salar de Atacama作为一个例子。这个映射过程中提出的计算效率的三维数值模型的基础上，提供的淡水和混合沃茨的水头校正的基础上，其密度变化，将它们转换成盐水头。经过这种校正后，泻湖和湿地的边缘地带的盐滩的特点的位置与区域最小水（盐水）heads.The不同的形态的混合区从这个3D映射所产生的混合区已被解释使用一个二维（2D）的流动和运输的混合区的理想化横截面的数值模型。该模型的结果显示了混合区的斜率，该斜率与通过3D映射获得的斜率相似，并且低于先前的模型。为了解释这种几何形状，使用2D模型来评估混合区几何形状中的非均匀性的影响。上部含水层渗透率越高，边坡越低，混合带越浅。出现这种情况的原因是，由于上层含水层的渗透率高得多，大部分淡水侧向补给流经上层含水层，从而降低了淡水水头。在这些水文地质系统的上部存在几米的高渗透性物质，如冲积扇或岩溶岩，这些物质通常与盐滩有关，足以大大改变盐水界面的几何形状。
Salt flat brines are a major source of minerals and especially lithium. Moreover, valuable wetlands with delicate ecologies are also commonly present at the margins of salt flats. Therefore, the efficient and sustainable exploitation of the brines they contain requires detailed knowledge about the hydrogeology of the system. A critical issue is the freshwater-brine mixing zone, which develops as a result of the mass balance between the recharged freshwater and the evaporating brine.The complex processes occurring in salt flats require a three-dimensional (3D) approach to assess the mixing zone geometry. In this study, a 3D map of the mixing zone in a salt flat is presented, using the Salar de Atacama as an example. This mapping procedure is proposed as the basis of computationally efficient three-dimensional numerical models, provided that the hydraulic heads of freshwater and mixed waters are corrected based on their density variations to convert them into brine heads. After this correction, the locations of lagoons and wetlands that are characteristic of the marginal zones of the salt flats coincide with the regional minimum water (brine) heads.The different morphologies of the mixing zone resulting from this 3D mapping have been interpreted using a two-dimensional (2D) flow and transport numerical model of an idealized cross-section of the mixing zone. The result of the model shows a slope of the mixing zone that is similar to that obtained by 3D mapping and lower than in previous models. To explain this geometry, the 2D model was used to evaluate the effects of heterogeneity in the mixing zone geometry. The higher the permeability of the upper aquifer is, the lower the slope and the shallower the mixing zone become. This occurs because most of the freshwater lateral recharge flows through the upper aquifer due to its much higher transmissivity, thus reducing the freshwater head. The presence of a few meters of highly permeable materials in the upper part of these hydrogeological systems, such as alluvial fans or karstified evaporites that are frequently associated with the salt flats, is enough to greatly modify the geometry of the saline interface.
影响因子：
5.4
作者：
E. Hamann;V. Post;C. Kohfahl;H. Prommer;C. Simmons
通讯作者：
E. Hamann;V. Post;C. Kohfahl;H. Prommer;C. Simmons