Solving for Dispersivity in Field Dispersion Test of Unsteady Flow in Mixing Flow Field: Mass Transport Modeling

AbstractA combined groundwater flow and mass transport model was constructed to simulate the migration of contaminants and to obtain dispersion parameters from a field dispersion test in unsteady flow in mixing flow field in groundwater. Aquifer parameters were obtained by a pumping test. Tracer tests were carried out in order to characterize the characteristics of groundwater flow and to determine the velocity of the pollutant diffusion process from the source to the pumping well. Groundwater head and velocity were analyzed in the groundwater flow model and the total dissolved solids (TDS) concentration was computed in the mass transport model. The observed drawdown and the observed TDS concentration were found to respectively match closely with the computed drawdown and TDS concentration

The hydrochemical characteristics and quality assessment of groundwater in Shuangliao City, China

In this study, a hydrochemical investigation was conducted in Shuangliao city to identify the hydrochemical characteristics and the quality of groundwater using descriptive statistics and correlation matrices. And on that basis, combined with Analytic hierarchy process (AHP), an improved two-level fuzzy comprehensive evaluation method is used to evaluate the groundwater quality. The results indicate that the major cations and anions in groundwater are Ca2+ and HCO3-, respectively. The chemical types are mainly HCO3—Ca type water, some areas are complicated due to the influence of human activities. The evaluation results show that the water quality in the area is mostly III type water, and the groundwater quality in some areas is IV or V water due to the influence of primary geological conditions or human activities. The groundwater quality in the East Liaohe River Valley and Shuangliao urban area is relatively poor, and in the northwest part which is the saline alkali soil area is also relatively poor

Extraction Method of Baseflow Recession Segments Based on Second-Order Derivative of Streamflow and Comparison with Four Conventional Methods

Baseflow recession analysis is widely used in hydrological research, water resource planning and management, and watershed hydrogeological research. The first step of baseflow recession analysis is to extract the baseflow recession segments from the hydrograph. Different extraction results lead to different analysis results. At present, the four major recession segment extraction methods applied by hydrologists are mostly based on experience, and there is no clear theoretical basis. Therefore, this study derives a second-order derivation (Sec-D) recession segment extraction method based on the power law relationship between storage and discharge. Moreover, by applying the Sec-D method and the four conventional extraction methods to four hydrological stations in the Tao’er River basin in northeastern China, the differences in the recession segment extraction, determination of basin-wide hydrogeological parameters, and groundwater balance estimation are compared. The results demonstrate that, contrary to the four conventional methods, the Sec-D method can effectively eliminate the early recession stage affected by the surface runoff or rainfall and some streamflow data with more than 1% non-sequential error. The hydraulic conductivity of the four basins estimated by the Sec-D method is between 2.3 × 10−5–4.9 × 10−5 m/s, and the aquifer thickness is between 131.2 and 202.5 m. However, the four conventional extraction methods may underestimate (by about 2.5 times) the basin-wide hydraulic conductivity and overestimate (by about 3 times) the aquifer thickness. The groundwater balance elements calculated by the Sec-D method and the four conventional methods present similar intra-annual fluctuation characteristics; the correlation coefficients of daily evapotranspiration calculated by the five methods ranged from 0.7 to 0.95, and those of daily effective groundwater recharge ranged from 0.95 to 0.99. The use of the Sec-D method in baseflow recession analyses is significant for future studies and can be combined with conventional methods

Hydrogeochemical Characteristics and Genesis Model of Jinjiang and Julong Hot Springs in Changbai Mountain, Northeast China

Changbai Mountain in China has been explored as a potential area for its rich hot springs including the Jinjiang and Julong hot spring groups. The hydrogeochemical characteristics and conceptual genesis models of the Jinjiang and Julong hot springs were evaluated by hydrogeochemical analysis, isotope analysis, rock sample analysis, hydrogeochemistry simulation, and geophysical exploration method. The results showed that HCO3− and Na+ were the most abundant anion and cation in the hot springs, and the hydrochemical type was Na-HCO3. And the hot springs are enriched with trace components such as H2SiO3 and Sr. The major gas composition of the Jinjiang hot springs and Julong hot springs were CO2, N2, and CH4, which were derived from the mantle. The chemical compositions were produced by feldspar and pyroxene mineral hydrolysis. The recharge source of the hot springs was atmospheric precipitation and was also influenced by evaporation, and the genetic models for the Jinjiang hot springs and Julong hot springs were as follows: the heat source of both was a magma body and heat was mainly migrated in the form of thermal conduction. The cap rocks were both composed of trachyte of Baitoushan formation, basalt of Junjianshan formation, and rhyolitic pyroclastic rocks of Changbai formation. The geothermal reservoir of both hot springs was a fracture zone with the lithology of volcanic breccia, sand, and gravel and volcanic breccia and marble, respectively

Hydrogeochemistry of Groundwater from Kazaure Area, NW Nigeria using Multivariate Statistics

This study was aimed at understanding the factors affecting groundwater for the benefit of water resources management. Groundwater collected from 18 sites over an area of 770 Km2 was analysed. Temperature (Temp.), pH, Total Dissolved Solids (TDS) and Electrical Conductivity (EC) were measured in the field and 15 chemical parameters analysed in the laboratory. Factor Analysis (FA) of physiochemical results indicated mineralization, weathering of silicates and K-feldspar, and anthropogenic sources were mainly responsible for groundwater chemistry. Hierarchical Cluster Analysis (HCA) revealed sample clusters were mainly controlled by structure rather than by lithology, water source or altitude because 86% of cluster I samples occurred along a NNE-SSW trending fault zone. It was thus concluded that water-rock interaction, tectonics and anthropogenic factors are responsible for water physiochemistry

Study on Ecological Threshold of Groundwater in Typical Salinization Area of Qian’an County

A suitable groundwater level is an important condition to maintain the stability of the vegetation community, especially in arid and semi-arid areas. The surface of Qian’an County in Western Jilin Province is often accompanied by salinization due to the influence of natural and human factors. In order to maintain the healthy development of ecological vegetation and reduce the risk of soil salinization, the concept of an ecological threshold of groundwater level is proposed, and two methods are used to determine the reasonable ecological threshold of groundwater. (1) Based on field investigation and indoor experiment, the data layer of soil texture, land use type and groundwater mineralization degree in the research area was established by using remote sensing technology and GIS technology. According to the thickness of vegetation root layer and the height of capillary rise of different soil and water types, the influence of groundwater salinity is considered, and the sum of the two is taken as the ecological threshold of groundwater in the study area. The reasonable threshold value of suitable growth of various vegetation crops is 3.76~5.66 m. (2) According to the relationship between the normalized vegetation index (NDVI) and the groundwater buried depth and phreatic salt, the groundwater buried depth and the mineralization degree under the best vegetation cover are analyzed as follows: the buried depth of groundwater is between 4.8 m and 6.1 m, and the salinity of groundwater is between 0.37 and 1.25 g/L, which are reasonable groundwater properties in the study area of the ecological threshold. This result not only enriches and broadens the content of groundwater research, but also helps to predict the prospect of water resource development

Potential Impact of In-Situ Oil Shale Exploitation on Aquifer System

The effects of heat on physical and hydraulic properties of oil shale were investigated. The porosity and water absorption of oil shale increased with increasing pyrolysis temperature. The porosity increased by 19.048% and water absorption increased by 0.76% when oil shale was heated to 500 °C. Thus, originally impermeable oil shale was converted to a permeable rock formation, facilitating interactions between surrounding groundwater and oil. Heated oil shale was immersed in water, which showed strong alkaline properties. The content of Ca2+ remained stable and a slight decrease in SO42− content was observed. Hydrocarbon content in the water samples reached maximum concentration within three days

Study on the influence of water-rock interaction on streamflow conductivity based on hydrograph separation

The conductivity of the streamflow is controlled by the content of the dissolved components, which mainly come from the water-rock interaction of the baseflow. This paper showed that the conductivity sequence controlled by water-rock interaction in the runoff process can be screened out by the two-parameter recursive filter method. The analysis of the streamflow and conductivity series of USGS gauge numbered 02298202 from October 2005 to October 2009 showed that the water-rock interaction controls the conductivity characteristics of the stage of streamflow recession. And with the increase of water-rock interaction time (T), the conductivity of the streamflow increases in a power function, which satisfies the equation C = 252.92T0.262

Hydrogeochemical Characteristics and Groundwater Quality Evaluation Based on Multivariate Statistical Analysis

Hydrogeochemical research and water quality evaluation are an important part of groundwater development and management projects in Dehui City, Jilin Province, China. We collected 217 groundwater samples in the study area and used two multivariate statistical methods, hierarchical cluster analysis and principal component analysis to classify groundwater; combined graphical method, piper diagram, and Gibbs diagram to characterize groundwater chemical types and distinguish the water chemical control mechanism; and fuzzy comprehensive evaluation method to evaluate groundwater quality. Three major categories have been identified. Most of the groundwater in the study area is Ca-HCO3 type water. The water chemistry control mechanism is determined to be based on water-rock interaction and less evaporation. From east to west in the study area, the total dissolved solids (TDS) gradually increased, and water quality gradually deteriorated. In the whole region, 79.26% of the groundwater is suitable for drinking. With Yinma River at the boundary, the water quality in the eastern part is excellent, while that in the southwest is poor. After appropriate treatment, it can be used in industry and agriculture. The excess NO3− is mainly affected by human activities. The unique geological conditions of the Songnen Plain result in an excess amount of Fe3+ and Mn2+ in some areas. This study determined the chemical characteristics of groundwater in the study area and distinguished water quality levels. The results will be helpful for the development and management of groundwater resources

Source and Mobilization Mechanism of Iron, Manganese and Arsenic in Groundwater of Shuangliao City, Northeast China

Excessive levels of Fe, Mn and As are the main factors affecting groundwater quality in Songliao plain, northeast China. However, there are few studies on the source and mobilization mechanisms of Fe, Mn and As in the groundwater of Northeastern China. This study takes Shuangliao city in the middle of Songliao plain as an example, where the source and mobilization mechanisms of iron, manganese and arsenic in groundwater in the study area were analyzed by statistical methods and spatial analysis. The results show that the source of Fe and Mn in the groundwater of the platform is the iron and manganese nodules in the clay layer, while, in the river valley plain, it originates from the soil and the whole aquifer. The TDS, fluctuation in groundwater levels and the residence time are the important factors affecting the content of Fe and Mn in groundwater. The dissolution of iron and manganese minerals causes arsenic adsorbed on them to be released into groundwater. This study provides a basis for the rational utilization of groundwater and protection of people’s health in areas with high iron, manganese and arsenic contents