额济纳盆地地下水补给机理研究

 黑河下游的额济纳盆地，气候干旱，降雨稀少，盆地内分布着复杂的地下水含水层，濒临崩溃的生态系统靠其有限的地下水资源维持着，如何有效的评价地下水资源量，怎样合理的开发利用地下水资源，以及近期黑河治理规划工程实施后，对地下水资源产生何种影响，成为亟待解决的问题。对此，应用皮帕尔（Piper）图解法分析地下水的水化学特征类型，结合区域构造水文地质、地下水流场和环境同位素，分析盆地内不同地区的地下水补给机理：发现自流井区为一小区域的沉积中心，其来源不同于其他以黑河河水为补给源的地下水，而是来自中蒙边境山区的补给；古日乃草原地下水主要依靠黑河河水通过古河道渗漏的补给，而不是巴丹吉林沙漠的补给；赛汗桃来沉积中心的深层承压水来自其邻近上游地区潜水的侧向渗流补给。利用放射性同位素氚含量，初步估算出不同地区地下水的更新期，其地下水年龄均低于35 a。为评价黑河干流规划对地下水资源所产生的影响、合理开发利用地下水资源、保护脆弱的生态环境提供科学依据。

Mechanism of Groundwater Replenishment in Ejin Basin

Ejin Basin underlying complex aquifer, lies in the lower reaches of Heihe River with arid climate and 39.8 mm mean annual precipitation. In Ejin Basin, because the balance of natural ecosystem is frangible to upset, it is very important to estimate and to rationally utilize the limited groundwater resources in order to maintain the balance. Water samples were collected from the Heihe River and from wells for chemical and isotopic measurement all over the basin. Piper diagram gives two main types of hydrochemical features. On the background of regional geology, combining isotope δ18O, Tritium and chemical analysis with groundwater flows indicated by shallow groundwater level's contour map, different kinds of groundwater source and how to replenish groundwater were discovered. In the north of the study area, artesian wells get them replenishment from the mountainous area at the boundary between China and Mongolia. Most of the groundwater resources replenishment in Gurinai oasis comes from Heihe River seepage flow by the highly conductive paleochannel, not from Badain Jaran Desert in terms of TDS and Tritium analysis. By radioactive isotope Tritium analysis, different groundwaters ages were approximately estimated, which are younger than 35 years. On such efforts, groundwater resources can be effectively evaluated with the engineering impact of The Heihe River Project.