Hydrochemical Characteristics and Multivariate Statistical Analysis of Natural Water System: A Case Study in Kangding County, Southwestern China

Abstract

Abstract:The utilization for water resource has been of great concern to human life. To assess the natural water system in Kangding County, the integrated methods of hydrochemical analysis, multivariate statistics and geochemical modelling were conducted on surface water, groundwater, and thermal water samples. Surface water and groundwater were dominated by Ca-HCO 3 type, while thermal water belonged to Ca-HCO 3 and Na-Cl-SO 4 types. The analyzing results concluded the driving factors that affect hydrochemical components. Following the results of the combined assessments, hydrochemical process was controlled by the dissolution of carbonate and silicate minerals with slight influence from anthropogenic activity. The mixing model of groundwater and thermal water was calculated using silica-enthalpy method, yielding cold-water fraction of 0.56-0.79 and an estimated reservoir temperature of 130-199 • C, respectively. δD and δ 18 O isotopes suggested that surface water, groundwater and thermal springs were of meteoric origin. Thermal water should have deep circulation through the Xianshuihe fault zone, while groundwater flows through secondary fractures where it recharges with thermal water. Those analytical results were used to construct a hydrological conceptual model, providing a better understanding of the natural water system in Kangding County.

Hydrogeochemical Characteristics and Conceptual Model of the Geothermal Waters in the Xianshuihe Fault Zone, Southwestern China

“…A total of 36 water samples were collected from geothermal springs, geothermal drilled water wells, and cold springs and rivers in the vicinity of the XFZ on 18-20 May 2017. Field sampling procedures and analytical methodology were described by [16]. Temperature, pH, alkalinity, and total dissolved solids (TDS) were measured in the field.…”

“…Hydrochemical parameters including pH and major ions were used for principal component analysis, which is helpful for tracing the sources of those ions [16,17]. The results of the principal component analysis include eigenvalue, percentage of variance, the cumulative percentage of variance, and the factor loading, presented in Table 1.…”

“…Geothermal springs are primarily found in the Yalabamei, Zhonggu, Erdaoqiao, and Yulingong geothermal areas of the XFZ (Figure 1c). Up to now, previous studies have interpreted the genesis of geothermal springs in the Erdaoqiao and Yulingong geothermal areas using geophysical and geochemical methods [16][17][18][19][20][21][22][23][24]. However, only a few previous investigations analyzed the geothermal springs in the Yalabamei and Zhonggu geothermal areas [25], and thus the conceptual model of the geothermal system is unclear.…”

Hydrogeochemical Characteristics and the Suitability of Groundwater in the Alluvial-Diluvial Plain of Southwest Shandong Province, China

“…If the samples are located below the y = x line, cation exchange is a prevalent reaction in groundwater, while the samples above the y = x line suggests the reverse cation exchange as a prevalent process (Equations (7) and (8)). Most of the water samples are located under the y = x line (Figure 7e), indicating that the ion exchange process causes a deficiency of Ca 2+ ions, which is an important result of silicate weathering [31]. Most of the samples are located between the silicate and carbonate (Figure 7f), suggesting that the dissolutions of silicate and carbonates are the prevalent hydrogeochemical reactions in the groundwater system in the study area [32].…”

“…If the equivalent ratio of (SO 4 2− + HCO 3 − )/(Ca 2+ + Mg 2+ ) is equal to 1, the dissolutions of carbonates (calcite and dolomite) and gypsum are the major hydrogeochemical reactions in groundwater system. In addition, the ratio of (SO 4 2− + HCO 3 − )/(Ca 2+ + Mg 2+ ) can be used to determine the ion exchange in a system [31]. If the samples are located below the y = x line, cation exchange is a prevalent reaction in groundwater, while the samples above the y = x line suggests the reverse cation exchange as a prevalent process (Equations (7) and (8)).…”