Theoretical and practical meaning of stagnant points of groundwater flow system in the Cretaceous Basin of the Ordos Basin

Groundwater flow systems, the Darcy’s Law and the Theis formula are the major theories of hydrogeology. The groundwater flow system theory is the guiding theory for groundwater investigation, especially for regional groundwater investigation. It is a powerful tool for identifing hydrogeological conditions. Stagnant points are the identifiers for the division of shallow, intermediate and regional groundwater flow systems and have been proved to be present theoretically. So far, stagnant points have not been found in reality. In this paper, stagnant points were found in a cross section in the Ordos Basin, using radioactive carbon and hydraulic methods. This paper drawn the conclusion that stagnant points are present, they occupy a certain area and TDS around the stagnant points are not high. The results are the basis for further analyses and improvement of groundwater flow systems.