Hydrogeology of the Ordos Basin, China

The Ordos Basin is located in the east of NW China that is composed of different aquifer systems. Karst groundwater is stored in the Carmbrian-Ordovician carbonates along the margins of the basin. Fissured-pore water is present in the Cretaceous strata in the central-western basin and pore water is stored in the overlying Quaternary deposits discontinuously. The main origin of groundwater in the basin is direct or indirect infiltration of precipitation. Groundwater flows from recharge areas to adjacent local discharge areas. Besides evaporation and abstraction, groundwater feeds springs and rivers, such as the Yellow River and its tributaries. According to the karst aquifer lithologic structure, the features of karst development and circulation, the karst aquifer is divided into three structural and circulation patterns. Based on the control of Cretaceous sedimentary environment, lithologic structure, lithofacies, and palaeogeographic characteristics, the Cretaceous system is divided into the northern desert simple plateau aquifer system and the southern loess plateau aquifer system. PACKER was used to obtain temperature, hydrogeochemical and isotope data at specific depths. Groundwater circulation is studied using hydrodynamic fields, temperature fields, isotopes, hydrogeochemical data and numerical simulations. According to the result, it is divided into local, intermediate and regional systems.

The Ordos Basin contains a wealth of natural resources including coal, petroleum, oil shale and natural gas. There are four national-classenergy bases, e.g. northern Shaanxi energy basin, Inner Mongolia Ordos base, eastern Ningxia energy base, and Longdong base. And it is one of the most important bases for China’s energy and heavy chemical industries. Because the basin is located in arid and semi-arid areas, the lack of water and its vulnerable ecological environment are the main limitations to the development of local economy and to the improvement of living standards. In order to assess the water resources and the utilization prospect and to provide the hydrological information for the establishment of the energy bases and economic development, groundwater investigation in the Ordos Basin has been carried out.