鄂尔多斯自流盆地地下水来源争议问题讨论

Discussion on the Origin of Groundwater in the Orods Basin

本文讨论了鄂尔多斯自流盆地地下水来源存在争议的两种学术观点,指出了前人关于鄂尔多斯地下水补给、径流、排泄模型所存在的问题:①在四水转化过程中缺少了最重要的研究内容——土壤水的运动,通过概念模型得到的地下水循环模型不能解释地下水分水岭与基底断裂带重合的事实。②部分学者在进行地球化学反向模拟的的研究中,没有对白云石、方解石中的同位素进行对比分析,碳同位素不支持模拟分析结果。③采用14C测定地下水年龄中受到深部CO2的干扰,在中国北方地区不适合采用14C测定地下水的年龄。笔者等通过黄土剖面土壤水中的氘—氧同位素与Cl-分布特征,指出鄂尔多斯盆地的降水非但不能补给到地下水中,而且土壤水的主要来源是地下水。鄂尔多斯自流盆地的主要补给源是外源水,深大断裂带是导水的主要通道。

Two controversial opinions on the recharge of theOrdos Basin groundwater were discussed in this study. The problems in the previous studies on recharge, runoff, and discharge models of the Ordos Basin were discussed ： （ 1 ） The soil water, the most important part of the conversion among atmospheric water, surface water, soil water and groundwater, is not taken into account. The groundwater circulation model obtained by the conceptual model cannot be used to explain the fact that watershed is in coincidence with the basement fault zone. （2） The comparison of the isotopic compositions in dolomite with that in calcite is not conducted in some scholars＂ studies of the geochemical reverse simulation, with the resuh that the simulation results can be applied to explain the C isotope compositions in dolomite and calcite. （3） 14 C can not be used to obtain the ages of the groundwater in north China because of the interference of the deep CO2. Based on the D, 18Oand C1- compositions in the soil water, it is pointed out that the precipitation is not the main recharge source of the groundwater and the soil water is fed by the groundwater. The groundwater in the Ordos Basin is recharged by the exogenous water and deep faults are the main water channels.