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This study enhances the understanding of the evolution of water transport in karst water flow systems. This paper explores the karst water flow system from a hydrogeochemical perspective. It has been discovered that in the recharge area, the hydrochemical effect of karst water is primarily influenced by dissolution and filtration. In the fault zone and concentrated discharge area, it is primarily influenced by mixing. In the geothermal area, the dominant factors are dissolution, precipitation, and dolomitization. From the southern to the northern area, the hydrochemical type of karst water gradually changes from HCO3-Ca type to SO4·Cl-Ca·Na type. Atmospheric precipitation is the primary recharge source of karst water, with a recharge elevation range of 181–1,495 m. According to geological drilling statistics, the groundwater transport depth transits from the shallow transport in the south to the deep transport in the north, with a depth range of 3,000–3,500 m, and using isotope data to obtain the groundwater retention time range is 6–27,000 years. The groundwater transport mode is divided into three levels: open-shallow transport karst cold water phreatic flow, semi-open-medium-deep transport karst cold water confined flow, and weak open-deep transport geothermal water confined water flow. HIGHLIGHTS This study has revealed the hydrochemical evolution and transport patterns of karst water in the Jinan spring area.; The transport mode of the karst water flow system in the monoclinic structure of the Jinan spring area has been classified.;

Extreme precipitation triggered by climate change is a hot issue of global concern. This study investigates changes in temporal trends of precipitation at Jinan City, Shandong Province over the last six decades. It first constructs a long series of measured daily precipitation data (1951–2017) and then exploits the relative variability, Mann–Kendall, and rescaled range analysis (R/S analysis) methods to update precipitation characteristics. Results indicate that: (1) annual precipitation varies over 116%, with 74.1% of total precipitation concentrated from June to September, especially for heavy rains and storm days; (2) at the 95% confidence level, the annual rainfall does not increase significantly (U = 1.15), but there is a significant upward trend in the spring (U = 2.08), whereas there is no significant downward trend in the fall (U = −1.03); (3) precipitation sequence mutates in 1990, consistent with spring precipitation series, while there are two to four mutations in summer, autumn, and winter. The above results will provide the theoretical basis and data support for the rational development of water resources in Jinan; meanwhile, studying the law of precipitation changes in Jinan City has important practical significance for flood disaster prevention. HIGHLIGHTS A latest measured long-sequence precipitation data set (over 60 years) is established;; Precipitation characteristics in Jinan are updated;; Annual precipitation varies over 116%, with 74.1% of total precipitation concentrated from June to September, especially for heavy rains and storm days;; Precipitation sequence mutates in 1990, consistent with spring precipitation series;; Future precipitation trends continue to increase.;

The stormwater management model (SWMM) was adapted and calibrated to Jinan, a typical piedmont city in China, to verify the large-scale applicability of the model to piedmont cities. Fourteen storms were used for model calibration and validation. The calibrated model predicted the measured data with satisfactory accuracy and reliability. A sensitivity analysis was then conducted to evaluate the impact of the model parameters; it showed that: (1) the model outputs were most sensitive to imperviousness and conduit roughness; and (2) infiltration parameters and depression storage play an important role in total runoff and peak flow. The urban drainage system of Jinan was assessed using urban design storms with the calibrated model, and the effects of engineered flood control measures were evaluated. The overall results demonstrate that SWMM is applicable on a large scale to piedmont cities. [ABSTRACT FROM AUTHOR]