Land subsidence is an environmental geological phenomenon with slowly decreasing ground elevation, The North China Plain is one of the areas with the most serious land subsidence in China, and Guangrao County is one of the subsidence centers. This paper is based on the hydrogeological and engineering geological data of Guangrao County, the groundwater monitoring data for many years and the land subsidence monitoring data, systematically analyzes the dynamic characteristics of groundwater, the distribution and evolution of land subsidence, and the correlation between groundwater exploitation and land subsidence development in different layers of this area. Based on Biot porous medium consolidation theory, establishes a three-dimensional fluid solid coupling numerical model of land subsidence in Guangrao County, restores the development process of land subsidence, predicts and analyzes the subsidence evolution law under different groundwater exploitation schemes, and proposes targeted prevention and control measures. The research results show that: the shallow groundwater forms a cone of depression with Guangbei Salt Field as the center, and the deep groundwater forms an elliptical regional cone of depression with the urban area as the center. The ground is gradually formed two small settlement areas with the urban area of Guangrao County and Guangbei Salt Field as the settlement center, and there is a trend of interrelated expansion. The three-dimensional fluid solid coupling model of land subsidence accurately restored the development process of land subsidence in the study area, predicted that under the current groundwater exploitation conditions, by 2040, the settlement of Guangrao urban settlement center will increase to 1,350 mm, forming a large regional funnel centered around the urban area, and gradually developing and expanding around. Prohibition of groundwater exploitation in the main funnel area is a more reasonable and effective exploitation plan to prevent the development of land subsidence.

The solute transport process in porous media is central to understanding many geophysical processes and determines the success of engineered applications. However, fundamental understanding of solute transport in heterogeneous porous media remains challenging especially when inertial effects are significant. To address this challenge, we employed direct numerical simulations in a variety of intrapore geometries at a high Reynolds number (Re = 10) flow regime, where recirculation zones (RZs) are present with significant inertial effects. We find that the volume of RZs depends on pore geometries. Moreover, RZs serve as an immobile domain that can trap and release solutes that lead to non-Fickian transport, characterized by the early arrival and heavy tailing of breakthrough curves and bimodal residence time distributions (RTDs). Lastly, the late time portion of RTDs is fitted to the power law function with determined exponent n, where n depends on the pore geometries and consequently the volume of RZs. Our study sheds light on the mechanisms of an immobile zone on the solute transport, especially improving our understanding of late time transport tailing in pressurized heterogeneous porous media.

The northwest area of Shandong Province is rich in geothermal resources. As renewable energy and clean energy with heat energy and water resources as a whole, more and more attention has been paid to it, and it is widely used in heating, breeding, bathing and other industries, good economic and social benefits have been achieved. In the process of long-term development and utilization of geothermal resources and deep groundwater, as both groundwater and geothermal resources belong to groundwater resources, they are utilized by underground pumping and extraction and overlap each other in vertical distribution, experts and scholars have been discussing whether there is a hydraulic connection between geothermal resources and deep groundwater and whether the exploitation of geothermal resources will affect the exploitation of deep groundwater. Based on the comprehensive analysis of the stratigraphic structure, hydrochemical and isotopic characteristics, groundwater regime and water temperature in the northwest of Shandong, it is concluded that the geothermal water in the sandstone reservoir in the northwest of Shandong has a weak hydraulic connection with the deep groundwater, it provides a reference for the protection of deep groundwater resources.

Groundwater is the primary source of water for human development in the Yishu River basin, and therefore characterizing groundwater quality is essential for sustainable development of groundwater resources in the region. This study aimed to determine the hydrochemical characteristics and water quality of groundwater in the Yishu River basin by sampling 45 wells in October 2016 and May 2017. Hydrochemical characteristics of groundwater were determined using integrated hydrochemical analysis and the groundwater quality was evaluated based on the water quality index (WQI). Groundwater of the Yishu River basin was characterized as weak alkaline hard water with mean concentrations of total hardness and total dissolved solids of less than 500 mg L−1 and 1000 mg L−1, respectively, and the principal chemical components of groundwater were higher in 2016 than in 2017. A Piper diagram showed that 64.4% of the water samples contained Ca–HCO3 type water and 27% contained mixed water (27%). The dominant processes driving the chemical composition of groundwater were found to be dissolution of silicate and carbonate minerals and cation exchange. The saturation index indicated that carbonate minerals were supersaturated, whereas gypsum, fluorite, and halite were unsaturated. The WQI indicated good groundwater quality in the Yishu River basin, with only one water sample classified as having "poor" water quality in 2016 and 2017, respectively. However, these samples contained high nitrate concentrations (> 200 mg L−1), which may be the result of domestic sewage discharge and/or the use of agricultural fertilizers.

Geothermal water resources are a kind of clean energy, which is a renewable resource to a certain extent and has a high value of development and utilization. To understand the hydrochemical characteristics, origins, and temporal variations of geothermal water quality in Tangtou, 13 geothermal water samples from 2007 to 2019 and geothermal geological conditions were collected. Cl− and Na+ are the major ions, which make the geothermal water belong Cl-Na type. The total dissolved solids values of geothermal waters were 1560–2512 mg/L and pH were in the range of 6.7–8.8. The development of faulted structures provides conditions for the formation of geothermal water. In addition, geothermal water is recharged by shallow underground cold water. Water-rock interaction, as well as mixing processes, in the process of long runoff path and the slower deep-water cycle is the main factor controlling the chemical composition of geothermal water. Calculated saturation index values indicated that the geothermal water was saturated with respect to silicate and carbonate minerals. Cation and silica chemical geothermometers indicated that reservoir temperatures ranged from 94.63 to 196.10 °C and from 69.13 to 123.75 °C, respectively. Based on the grey relational analysis, the main physicochemical components of geothermal water are obviously correlated with the geothermal water exploitation and precipitation. Overall, affected by exploitation and precipitation, main physicochemical components (such as the total dissolved solids, total hardness, temperature, Na+, Ca2+, Cl−, K+, and Mg2+) showed a certain stage.

The alluvial-diluvial plain of southwest Shandong Province is an important agricultural economic zone and energy base in Shandong Province. Groundwater plays an extremely significant role in the development of the regional social economy. In this study, 50 sets of water samples, collected from 25 wells during October 2016 and June 2017, were utilized to determine the hydrogeochemistry and the suitability of groundwater in the alluvial-diluvial plain of southwest Shandong Province for different applications, such as drinking and irrigation. Most of the water samples could be classified as hard-fresh water or hard-brackish water, and the dominant water types were HCO3-Na and mixed types. Water-rock interactions and evaporation were the dominant controlling factors in the formation of the hydrochemical components in the groundwater. Dissolutions of silicate, calcite, dolomite, and gypsum are the major reactions contributing and defining the groundwater chemistry in this plain. Moreover, cation exchange is a non-negligible hydrogeochemical process in this plain. Calculated saturation index (SI) values indicate that aragonite, calcite and dolomite are saturated, while the SI values for gypsum and halite are unsaturated. Based on fuzzy comprehensive evaluation, the groundwater quality ranges from excellent to very poor. More than 50% of all groundwater samples from 2016 are categorized as poor or very poor, suggesting that the water from these wells is not suitable for drinking. According to the sodium adsorption ratio and percentage sodium, most of the samples are suitable for agricultural irrigation. Overall, the quality of the groundwater in 2017 was found to be better than in 2016.