Dynamic evolution of karst water levels and its controlling and influencing factors in Northern China: a case study in the Dawu water source area

The Dawu water source is the most important urban water supply source in Zibo City, Shandong Province, China. In this paper, the karst water level, precipitation, exploitation and flood discharge data during 2012–2018 were used to study and explore the characteristics and factors that control and influence the dynamic evolution of the karst water level in the Dawu water source area. The results showed that the dynamic evolution of the karst water level from 2012 to 2018 can be divided into three stages: (1) from 2012 to 2013, the karst water levels were relatively stable and maintained at approximately 36 m. (2) However, the karst water levels decreased from 30.5 to 4.2 m with a decline rate of 6.58 m/a from 2014 to 2017, and the rapid decrease caused a change in the runoff of the karst water flow field. (3) The karst water flow was restored to the original mode of south to north flow with the increase in the karst water level in 2018. The results of the correlation analysis and hierarchical cluster analysis showed that flood discharge, precipitation and exploitation all influence karst water level dynamic changes in the Dawu water source area. Among them, the increase in exploitation was the main reason for the karst water level decline, the flood discharge from the Taihe reservoir is the most direct and effective recharge source. The results of the principal component analysis showed that the influencing intensity of the three factors was constantly changing with time. The main factor that influenced the karst water level dynamic changes in the Dawu water source area was flood discharge in 2012 and 2013, exploitation in 2015 and 2016 and precipitation in 2018. Although in 2014 and 2017, the main factors were the combination of precipitation, exploitation and flood discharge.