Water circulation model of karst water system in Jinan spring area

ABSTRACT This study employs field monitoring, hydrochemical analysis, lab experiments, and tracer tests to characterize multilevel groundwater flow systems and circulation patterns in karst aquifers, establishing a classification framework for spring protection. The main findings are as follows: (1) The Jinan area comprises two first-order karst water systems, specifically the Jinan Monocline Karst Water System and the Laiwu Basin Karst Water System. The Jinan Monocline system is further subdivided into five second-order intermediate flow systems. (2) The multilevel karst water circulation patterns are primarily classified into three major categories. The unconfined local flow system includes three circulation patterns. The confined intermediate flow system comprises three patterns, with the window-type intermediate system further divided into three subtypes. (3) The local flow system performs water conservation functions, serving as an indirect recharge source for the four major spring groups. The intermediate flow system constitutes the primary direct recharge source, mandating rigorous protection of the Cambrian-Ordovician karst aquifer in its recharge area. The confined regional system with deep circulation must adhere to the ‘heat extraction without water withdrawal’ development principle, preventing geothermal development activities from impacting the sustainable discharge of the spring clusters.