中国西北内陆干旱盆地地下水形成演化模式及其意义

The formation and evolution model of groundwater and its significance in inland arid basin,northwest china

随着系统理论分析方法的引入和同位素、遥感、计算机技术和先进物探手段等的应用，内陆干旱区的地下水勘查与研究得到迅速发展。本文以作者在中国西北地区近十几年的地下水勘查与研究成果为主要基础，将内陆干旱盆地平原区地下水划分为四级地下水流系统，即山前局部地下水流系统（Ⅰ）、区域地下水流系统（Ⅱ）、滞流地下水流系统（Ⅲ）和细土平原区易变的局部地下水流系统（Ⅳ）。盆地地下水的形成演化和盐分迁移主要发生在Ⅰ、Ⅱ和Ⅳ这三级水流系统中。山前局部地下水流系统（Ⅰ）的地下水接受补给条件好，径流交替积极，以盐分溶滤作用为主。在区域地下水流系统（Ⅱ）和易变的局部地下水流系统（Ⅳ）共同作用下，地下水和地层中的盐分在水平方向上从盆地边缘向中心迁移和聚集，在垂向上则从深部向浅部迁移和聚集。

Hydrogeologic research of arid regions has got a rapid development with the introduction of systematic analysis method and the application of new technologies,such as isotope,remote sensing,computer and advanced geophysical prospecting.Based mainly on the authors' works of groundwater exploration and research in Northwest China in recent 15 years,this article divides the groundwater of inland arid basin into 4 grades of groundwater flow system.They are the local foreland groundwater flow system (Ⅰ),the regional groundwater flow system (Ⅱ),the stagnant groundwater flow system (Ⅲ) and the changeable local groundwater flow system (Ⅳ) in alluvial plain.The formation and evolution of groundwater and salt migration in the basin are mainly included in the groundwater flow systems Ⅰ,Ⅱ and Ⅳ.For the flow system Ⅰ,it has a good condition of groundwater recharge and runoff,and belongs to salt leaching zone.Under the combined action of flow systems.Ⅱ and Ⅳ,the salt in groundwater and sediment migrated and accumulated from the foreland plain to the basin center horizontally ,and from deeplevel to shallow vertically .This is the main reason why the deep groundwater is relatively fresh and the shallow groundwater is salted in the vast alluvial plain,and why there exists deep “lingual fresh aquifer” extending from the foreland to the center of a basin.