Red Layer Of Shallow Groundwater Hydrogeochemical Characteristics Of Feng Huang Temple In Enyang District Of Bazhong

Bazhong locates in the red layer region of Northeast Sichuan, where water is relatively poor. In 2013, FengHuang Temple was proposed as the site for Bazhong airport. Thus to study the occurrence and characteristics of Hydrogeochemical shallow groundwater of FengHuang Temple helps to understand the formation and environment of its shallow groundwater, providing a scientific basis for the groundwater exploitation and sustainable development of Bazhong airport. And also helps to disperse farmers' drinking water problems in the red bed hill region, provides reference for groundwater occurrence rule and water chemical form in similar areas.In this paper, the red layer of shallow groundwater of FengHuang Temple in Bazhong city is the object of this study, based on the collection of previous studies, geology and meteorology and hydrology data of the research area, combining the hydrogeological investigations on field water sampling inspection, according to topographical features and types of groundwater in the study area, aquifer medium, burial conditions, the relationship between the runoff discharge and dynamic characteristics of divided hydrogeological unit, based on the research of the different typical watershed of hydrogeological units, the occurrence characteristics of shallow groundwater is confirmed. By different hydrogeological unit composition of shallow groundwater and hydrochemical classification of multivariate statistical analysis, the hydrogeological unit hydrochemistry type and the relationship between the ion components are determined. Based on the water chemical equilibrium calculation and analysis, the water chemistry of hydrogeological unit were studied, the results obtained are as follows:?1? Rolling groove valley hydrogeological units distributed in tread mud bridge-He Guba- Ming Yangchang and on both sides of Feng Jiagou, local troughs on both sides of the mountain are above sea level 380⁴40m, the bottom elevation 350³70m, gully relief between valleys, width is generally 200⁵00m. The shallow fissure water storage medium by shallow mudstone weathering fissures, and the shallow groundwater is mainly formed by underlying shallow sandstone weathering fracture with shallow weathered fissure diving, weathering fissures diving by atmospheric precipitation recharge, groove on both sides of the mountain valley for supplies, low-lying areas along the weathering fissure zone to the terrain, buried in the low-lying in valleys, flatland, depression zone. Platform-shaped valley slope hydrogeological units is mainly distributed in terraces and erosion gully erosion at the distribution area of about 60km2, accounting for 88% of the study area. The topography and more elongated, narrow strip, its temporary ditch side slopes of the valley by the soft and hard rock interbedded crack and structural factors such as the formation of a multi-stage control generally varies in width eroded plateau, erosion small platform area, generally less than 5km2 platform widths ranging from a few to several hundred meters, mostly "strip", "oval", "Changyuan" shape; sulcus mostly perennial or seasonal ditch water, mostly in a "V". The underlying storage medium of shallow groundwater in the area is formed by shallow mudstone weathering fissures and weathering fissures of shallow sandstone, mainly perched water, its distribution in the study area is relatively fragmented, main stranded in the platform rear mountain slope toe and back, buried shallow, runoff time is short, the groundwater dynamic change are greatly influenced by climate factors.?2? By Shukaliefu classification and Piper View of three lines, the wide and gentle troughs and flat-shaped valley slope hydrogeological units of shallow groundwater chemical is divided into HCO₃-Ca type water and HCO₃-Ca+Mg type water. Wide slow troughs hydrogeological units HCO₃-Ca+Mg type water main platform is located in the gully region, Flat-shaped valley slope hydrogeological units HCO₃-Ca+Mg type water is distributed in the upper reaches of the waterways, while the remaining areas are mainly HCO₃-Ca+Mg type, indicating that Mg²⁺ is mainly concentrated in the upper reaches of the river system, and the shorter route runoff, which may be the source of dissolved magnesium sulfate is formed.?3? Through the analysis of wide troughs and flat-shaped relief valley slope hydrogeological units of shallow groundwater parameters in the study area, the shallow groundwater?shallow weathered zone fracture water? as a whole is alkaline, are freshwater; Two kinds of hydrogeological unit of shallow groundwater in the study area cations are given priority to with Ca²⁺, anion were mainly HCO₃-; K⁺, Na⁺ and Cl^- coefficient of variation is opposite bigger, reflects their larger changes in groundwater levels, is the sensitive factor change with environmental factors, Ca²⁺, Mg²⁺ and HCO₃- and SO₄²- coefficient of variation is relatively small, reflecting their relative stability in groundwater levels.?4? Using correlation analysis and cluster analysis, mutual authentication relationship between the groundwater components of different hydrogeological units, to further define the relationship between the different hydrogeological units of shallow groundwater in the study area of each component, drawn-relief trough District SO₄²- close and Ca²⁺, indicating that the area may have calcium sulphate mineral composition. Mg²⁺, Ca²⁺, HCO₃- are closely related in the flat-shaped valley slope region, there may be calcium, magnesium carbonate dissolved minerals precipitate, and the flat-shaped valley slope cuts intensively, good conditions of shallow groundwater runoff and discharge, indicating strong effect of regional leaching.?5? By drawing different hydrogeological units of the components of shallow groundwater and Gibbs Fig ion ratio coefficient map, the different hydrogeological units of shallow groundwater in the study area is consistent, In order to dissolve the carbonate rocks containing calcium carbonate and aluminum silicate minerals, there is a small amount of Ca²⁺ and Na+, Mg²⁺ and Na+ cation exchange. Using water chemical equilibrium calculation method further proves the chemical causes. The use of chemical water balance calculation method demonstrates its water chemistry cause. Through the calculation of CO2 partial pressure, saturation index of calcite and draws feldspar- water aluminum ore- kaolinite-SiO₂-CO₂ system stability field map, it is concluded that the groundwater system overall is open system, in the calcite is mostly in the non saturated condition, groundwater in the flow in the process of continuous dissolved calcite, Ca²⁺ content increasing, leaching effect is strong, albite, anorthite and potassium weathered feldspar dissolved into kaolinite stage, part of the arrival of sodium montmorillonite and calcium montmorillonite stage. Red layer weathered clay with surface charge, under certain conditions, the adsorption of groundwater in the Na+, the groundwater dissolved in the Ca²⁺ can be replaced by the adsorption of Na+, the occurrence of cation adsorption.