| Chuxiong Prefecture belongs to the arid area of the central region of Yunnan Province. The spatial and temporal distribution of water resources is extremely uneven, so it is difficult to centralized use the groundwater exploited by red beds wells. The hydrogeological conditions of the red beds in Chuxiong are complicated, the study on hydrochemical characteristics of groundwater in red beds are scattered, the hydrochemical characteristics of the groundwater in the red bed have not been comprehensively and thoroughly mastered. In order to study the hydrochemical characteristics and spatial distribution of the red beds groundwater in Chuxiong area, representative water samples of different types of red beds groundwater in the study area were collected, the hydrochemical spatial model of the red beds was established by Arc GIS software, and the hydrochemical data was visualized.Analysis of red beds groundwater hydrochemical spatial distribution characteristics in Chuxiong area has important reference basis for the study of red beds groundwater circulation system, which can provide recommendations for the effective development and utilization of groundwater in red beds of Chuxiong area.Through the research, the main results are as follows:(1)The groundwater of the red beds in Chuxiong area is the weathered fissure water, the interlayer fissure water, the dissolved pore fissure water. In the divisiory hydrogeological unit, groundwater flow along fissure or bedding plane in Mouding basin, Luhe basin, Guangtong basin hydrogeological unit, and carved by valleys to expose spring point, discharge into river valley or river. Groundwater mainly for the nearest recharge and discharge in the Tianzimiao, Boluohe hydrogeological unit. Deep interlayer fissure water discharge into spring point underneath the temple and superficial weathering fissure water flow along fissure plane, nearest recharge and discharge in Nanhua basin hydrological unit. Superficial weathering fissure water flow along fracture network and deep interlayer fissure water axial circulate around the syncline to form confined water, and discharge into valleys in Chuxiong basin hydrology unit.(2)Through the study on 92 groups of hydrochemical constant component data, combined with the geological section, we sum up the hydrochemical characteristics and control factors of red beds groundwater:As the main groundwater types in the research area, weathering fissure water is greatly influenced by environment, the cations in groundwater is mainly Ca2+, anion is mainly HCO3-, mineralization degree is between 250~400mg/L and hydrochemical types is mainly HCO3-Ca. Interlayer fissure water is mainly influenced by the rock properties(lithology, thickness of single layer and adjacent strata combination), the cations in groundwater is mainly Ca2+, anions are mainly HCO3-and SO42-, when sandstone thickness is 100~200m, mineralization degree is between 500~700mg/L, when the thickness is 200m~300m, mineralization degree is between 300~500mg/L, hydrochemical types are mainly HCO3-Ca and HCO3·SO4—Ca. Dissolved pore fissure water is mainly influenced by gypsum salt mass in the water-bearing complex, the cations in groundwater are mainly Ca2+, Na++K+, anions are mainly SO42-, HCO3-and Cl- take second place, mineralization degree is between 800~1100mg/L, hydrochemical types are mainly HCO3·SO4—Ca, HCO3·Cl—Ca and SO4—Ca.(3) Using the theory of AHP analytic hierarchy process to set the hierarchical structure of the model, and proceed judgment matrix, construct smooth flow index judgment matrix, we get the water chemical components of the index weight: HCO3-is 0.4247, SO42- is 0.1161, Cl- is 0.0312, K++Na+ is 0.0555, Ca2+ is 0.2613, Mg2+ is 0.1112.(4) Using Arc GIS to analyze all the information layers, the distribution of the hydrochemical and the circulation system of the red beds in Chuxiong area is obtained by using the weighted superposition method:The concentration of K++Na+ ion is higher in the drainage area and the center of the basin, the content is between 30~70mg/L; Ca2+ ions gathered in the drainage area of the each unit, the content is between 140~280mg/L; Mg2+ ion concentration in the runoff area of each unit, the content is between 60~100mg/L; Cl- ions gathered in the drainage area and salt formation of each unit, the content is between 170~380mg/L; SO42- ions gathered in the drainage area of the unit, the content is between 350~650mg/L; the HCO3- mainly concentrated in the recharge area of each unit, the content is between 210~700mg/L; p H is weakly alkaline; the content of TDS is higher in the drainage area of each hydrogeological unit and the central area of the basin, the content is between 800~1200mg/L. Hydrochemical types are mainly HCO3— Ca and HCO3·SO4— Ca.In Nanhua basin, Luhe basin, Chuxiong Basin, Guangtong basin unit groundwater circulation system, groundwater flow from recharge area of the mountains to the plains of the drainage area, showing the feature of hydraulic gradient from big to small, runoff speed gradually slows down, centralized recharge, dispersed discharge, runoff alternately change from strong to weak, From mountain recharge area to the Central Plains drainage area, groundwater In Mouding basin unit have the characteristics of large hydraulic gradient, quicker runoff speed, smoother runoff, positive alternation. While in Tianzimiao, Boluohe unit, groundwater showing a quick speed, short runoff pathway, quick discharge feature.(5) Based on the analysis of the hydrochemical spatial distribution of the red beds groundwater in Chuxiong area, combined with the utilization and the water quality characteristics of the red beds groundwater in the research area, we put forward the effective development and utilization suggestions: Weathering fissure water is suitable for shallow wells development, single well households or small scale household water supply, interlayer fissure water is suitable for development of a variety of tube well, deep well centralized water supply or lead spring water, dissolved pore fissure water, dissolution pore and fissure water is suitable for medium and deep length wells development, centralized water supply, also acquire the same shallow wells development conditions as the weathering fissure water. |
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