In order to ensure a sustainable water resource for residents of the lower reaches of the Changhua River on Hainan Island, it is crucial to understand the chemical characteristics and formation mechanisms of their shallow groundwater. To achieve this, we collected and analyzed 100 groundwater samples using various methods. Our findings indicate that the groundwater is generally near-neutral to weakly alkaline, suggesting an oxidized environment. We identified 56 chemical types, with Ca•Na-HCO₃ and Ca-HCO₃ being the most common. Water–rock interactions—particularly with silicate rocks—are the primary factor influencing the water’s chemical characteristics, with Na⁺ and K⁺ coming from the leaching of silicate rocks, and Ca²⁺ and Mg²⁺ originating from the dissolution of carbonate rocks. Unfortunately, human activities such as agricultural practices and domestic sewage have had a significant impact on the groundwater, with NO₃⁻ levels surpassing SO₄²⁻ in most samples. These findings provide valuable insights into the development and protection of the shallow groundwater in this area.

With the rapid development of cities in northwest China, there has been an increasing focus on groundwater pollution in plateau cities, specifically the common occurrence of nitrate pollution. The special climatic, geological, and geomorphological characteristics of plateau and river valley cities contribute to distinct groundwater chemical characteristics. Therefore, the formation and evolution process of groundwater nitrate contamination differs from that of plain cities. To explore these issues, we conducted an analysis of eight major ions in various groups of water samples obtained from rivers, springs, and groundwater in Haidong. By utilizing factor analysis and correlation analysis, we were able to identify the characteristics and formation of groundwater chemistry and nitrate pollution in Haidong. Our findings reveal that the chemical characteristics of groundwater in Haidong are primarily controlled by rock weathering, mineral dissolution, and evaporation, leading to the formation of highly mineralized groundwater. Additionally, the excessive nitrate content in certain areas is a result of domestic sewage discharge and agricultural fertilizer use, exceeding Chinese drinking water health standards. Furthermore, for cities located in valleys, the geological structure significantly impacts the nitrate content of groundwater in different regions. Areas with obstructed groundwater flow tend to have higher nitrate levels, whereas regions with unobstructed groundwater experience lower nitrate concentrations. Notably, shallow groundwater is more vulnerable to nitrate pollution compared to deep groundwater. This study holds great significance in understanding the chemical characteristics of groundwater and the formation and evolution of nitrate pollution in highland river valley cities.

The lower reaches of the Changhua River are located in the northwest of Hainan Island, and the shallow groundwater in this area is the main water source for residents living at both sides of the river. In order to sustain the exploitation and use of water resources in this area, it is essential to clarify the chemical characteristics and the formation mechanism of the groundwater. We collected 100 sets of shallow groundwater samples from the lower reaches of the Changhua River, and analyzed the chemical characteristics of the groundwater in shallow aquifers as well as its controlling factors by means of the methods including descriptive statistical analysis, Piper diagram, Gibbs diagram, and ion ratio. The results show that the overall characteristics of groundwater in the study area are near-neutral to weakly alkaline nature, indicating a generally oxidized environment. The groundwater involves in 56 chemical types, and the most predominant types are Ca•Na-HCO3 and Ca-HCO3, respectively. NO- 3 has become a macro component exceeding SO2- 4in most of the sampling groundwater, suggesting a significant impact of human activities in this area. At the same time, the chemical characteristics of groundwater in the study area are mainly affected by the water-rock interaction, while the water-rock interaction is mostly affected by the dissolution of silicate rocks and less by the dissolution of carbonate rocks and evaporite rocks. According to the ion ratio results, Na+ and K+ in the study area are mainly from the leaching of silicate rocks, Ca2+ and Mg2+ are mainly from the dissolution of carbonate rocks, in addition to a certain degree of cationic exchange. NO- 3 is mainly related to human activities, and the human activities are more affected by agricultural activities and domestic sewage than by industrial and mining activities. This study can provide a reference for the development and protection of shallow groundwater in the lower reaches of the Changhua River.

Due to the scarcity and uneven distribution of data, as well as the complexity of geological conditions, high-precision 3D hydrogeological structure modeling, especially at large scales, remains a significant challenge in the field. To address this issue, this study undertakes an in-depth analysis of the correlation between stratigraphic and hydrogeological structures. Utilizing the cumulative thickness of various aquifer types as a criterion, we establish a quantitative correlation model between stratigraphic and hydrogeological structures. This innovative approach transforms the task of 3D hydrogeological structure modeling into 3D geological structure modeling, where data are relatively abundant, thereby overcoming the data scarcity problem. To demonstrate the scientificity and feasibility of our approach, we utilize the 3D hydrogeological structures modeling of Wuhan’s metropolitan development area (MDA) as a case study. This study provides a quantitative criterion for the correlation between stratigraphic and hydrogeological structures, addressing the subjectivity and arbitrariness of previous qualitative evaluations. Additionally, it offers a scientific solution to the data scarcity issue commonly encountered in 3D hydrogeological structure modeling. Consequently, this study holds significant scientific value and practical implications.

With the rapid development of cities in northwest China, there has been an increasing focus on groundwater pollution in plateau cities, specifically the common occurrence of nitrate pollution. The special climatic, geological, and geomorphological characteristics of plateau and river valley cities contribute to distinct groundwater chemical characteristics. Therefore, the formation and evolution process of groundwater nitrate contamination differs from that of plain cities. To explore these issues, we conducted an analysis of eight major ions in various groups of water samples from rivers, springs, and groundwater in Haidong. By utilizing factor analysis and correlation analysis, we were able to identify the characteristics and formation of groundwater chemistry and nitrate pollution in Haidong. Our findings reveal that the chemical characteristics of groundwater in Haidong are primarily controlled by rock weathering, mineral dissolution, and evaporation, leading to the formation of highly mineralized groundwater. Additionally, the excessive nitrate content in certain areas is a result of domestic sewage discharge and agricultural fertilizer use, exceeding Chinese drinking water health standards. Furthermore, for cities located in valleys, the geological structure significantly impacts the nitrate content of groundwater in different regions. Areas with obstructed groundwater flow tend to have higher nitrate levels, while regions with unobstructed groundwater experience lower nitrate concentrations. Notably, shallow groundxwater is more vulnerable to nitrate pollution compared to deep groundwater. This study holds great significance in understanding the chemical characteristics of groundwater and the formation and evolution of nitrate pollution in highland river valley cities.

Currently, many types of software including those used for environmental geological survey, investigation of groundwater resources, groundwater pollution investigation and urban geological environment investigation have been developed by hydrogeological investigation industries. In order to rationally and scientifically evaluate the quality of the software and guide software development, a study on hydrogeological survey software evaluation was conducted unsing an index system. A weighting method was used to establish a three-stage quality indicator system model including technical modules, test items and test sub-items. The evaluation index system model was divided into seven technical modules, 26 test items and 71 test sub-items, and scoring methods and scoring criteria of various evaluation indicators were established. The groundwater resources survey software was evaluated and the evaluation index system model was tested. Hydrogeological survey software evaluation is still in its infancy, so the hydrogeological survey software evaluation index system is the primary probe for hydrogeological survey software evaluation standards and norms.