中文摘要：

鄂尔多斯盆地西北部最干旱的乌海地区地下水水位近几年来持续上升,地下水溢出地表形成了一些水泡子,部分居民房屋地基遭受到渗水的浸泡。分析乌海地区渗水、地下水、地表水、降水中的同位素与水化学成分,结合水量平衡分析与地质构造特点,对乌海地下水水位上升的原因进行深入研究。结果表明：乌海地区降水与地下水的δ18O-δD关系点分布没有落在同一条蒸发线上,当地降水对乌海地区的地下水没有补给;乌海地区南北向断裂带上地下水的δ18O与δD值比东西向断裂带上的富集,溶解总固体（TDS）小于1 g/L,与乌海地区的涌水一致,由此推测乌海地下水水位上升主要是因为南北向断裂带涌水所致;鄂尔多斯地区地下水的3He/4He与3H分析结果表明,岩石圈中的高导低速层可能是深循环地下水的导水构造。

英文摘要：

The groundwater level in the Wuhai area,which is the most arid area in the northwestern Ordos Basin,has continuously risen in recent years. The groundwater overflows to the surface and forms small lakes,causing the foundations of the houses of local residents to be immersed by water. Through analysis of the isotopes and hydrochemical compositions in the seepage,groundwater,surface water,and precipitation across the Wuhai area,and based on water balance analysis and geological structural features,the reasons for the groundwater level rise of the study area are examined. The results show that the deuterium and oxygen isotopic compositions of precipitation and groundwater in the Wuhai area are not scattered along the same evaporation line, indicating that the groundwater is not recharged by local precipitation. The groundwater in the north-south trending fault zone（ ρ（ TDS）〈 1 g /L） in the Wuhai area is more enriched in deuterium and oxygen isotopes than that in the west-east trending fault zone. These characteristics are in accordance with those of the overflowing water in the Wuhai area,suggesting that the rise of the groundwater level is caused by the overflowing water in the north-south trending fault zone. Analysis of3 He /4He and3 H in the groundwater of the Ordos Basin shows that the high-conductivity and lowvelocity layer in the lithosphere may be the drainage structure of deep-circulating groundwater.