Groundwater circulation patterns in the northern Cretaceous Basin, China

Information of groundwater level, isotope and hydrogeochemistry from different depth were taken by the Packer system. Through a detailed study of a typical profile in the northern basin, groundwater circulation can be divided into three patterns. Shallow circulation pattern: This pattern is characterized by fast circulation, high renewal capacity, short circulation path, and good water quality. Circulation depth is generally 150 ~ 200m, Groundwater age is between 20 ~ 50 years. Middle circulation pattern: Compared with the shallow circulation pattern, middle circulation system is involved with more extent and deeper with the maximum circulation depth of up to 550m.The groundwater age is less than 5000 years; Deep circulation pattern: In this system, the groundwater is most extent and deepest, long circulation path, and piston movement, weak circulation. The groundwater flowing rate is extremely low and circulation depth varies between 800~1000 years. Groundwater age is more than 5000 years, and this pattern has weakly renewal capacity.