Characteristics, formation models and water cycle differences of ten major spring groups in Jinan City

The purpose of this work is to systematically and comprehensively understand the ten major spring groups in Jinan City. By comparison， characteristics of the distribution，flow，landscape and water quality of these spring groups are revealed. Through fine description of hydrogeological structure and analysis of spring discharge conditions，the genetic differences of the spring groups are further clarified，the formation modes of spring water are summarized，and the differences of water cycles are clarified. The results show that the ten spring groups can be roughly divided into two categories，six ascending spring groups in the drainage area and four descending spring groups in the southern supply area. Their formation models can be divided into five types：structural uplift and limestone "sky light"，structural uplift and crack connection，shallow multi-layer sand layer and high permeability clay conduction， crack cutting and erosion overflow. Macroscopically，the water circulation of the ten spring groups in Jinan is controlled by the northward inclined monocline structure，in which the input conditions，transport systems and output modes have small differences. On a micro scale，there are obvious differences in the way of spring water output among the six pressure spring groups， of which the type，thickness，permeability of limestone overburden and burial depth of limestone roof vary greatly，resulting in different spring water outflow forms，flow and water quality，forming their own unique landscapes. The detailed study on the micro genesis of karst springs can provide an important geological basis for the classified protection of the ten spring groups in Jinan.