| Taohuahe, Langzhong City, is located in the Red Bed Section in Sichuan Province. The shallow groundwater has been utilized as the drinking water for a long time, and the quality of the shallow groundwater direct affects the health of the local residents, therefore researches for groundwater use safety in the area is of much significance.The groundwater use safety of this area is investigated through groundwater quality, groundwater quantity and soil environment quality, giving 47 groups of water samples and 76 groups of soil samples. Combined with the previous geological data, we study the groundwater types, hydrogeochemical characteristics and the distribution of groundwater hydrogeochemical type. The groundwater environment quality is evaluated by Nemerow Index and synthetical index method, the groundwater quantity is calculated by recharge method, specific yield method and the method for average distribution of well, and the soil environment quality is evaluated by geoaccumulation index and Nemerow Index. On the basis of the above research results, groundwater use safety is studied, leading to the corresponding zone division. The influence factors on groundwater quality of this area are analyzed and the corresponding protection methods are put forward in accordance with the current situation of the area. And the main research results in this paper are as follows:1. The types of shallow groundwater in this area can be classified into pore water and fissure water, and the major of aquifers lies in the quaternary unconsolidated formation and JianmenguanFm sandstone of cretaceous system. The dominant ones of the hydrogeochemical types are HCO3-Ca type and HCO3+SO4-Ca type.2. The water quality evaluation was carried out by Nemero Index, and the groundwater environment quality is classified into three grades: good, poor and bad, which is consistent with the evaluation result of the synthetical index method. Thus it can be concluded that the main factors influencing the groundwater quality of the area include turbidity, pH, total hardness and ?.3. The natural recharge resources are calculated by recharge method when the rainfall guarantee degrees are 95%, 75% and 50%, giving the results that the annual planning productions account for 3.02%, 2.80% and 2.35% respectively at the above three degrees, and that the natural recharge resources can satisfy the exploitation demand of the groundwater in the area at any rainfall guarantee degree. On the basis of the calculation of groundwater storage resources through specific yield method, the author arrives at the conclusion that the refresh rate of the groundwater storage resources is 19.64% and the guarantee degree of the refresh rate of groundwater in the area is high. Besides the exploitable yield of groundwater is calculated by the method for average distribution of well and the guarantee rate is 62.14%, a high guarantee rate.On the basis of the research concerning the natural recharge resources, refresh rate of the groundwater storage resources, guarantee rate of groundwater exploitable yield, it arrives the conclusion that the groundwater quantity in the area is enough.4. The soil of the area is mainly contaminated by Cd?Hg???? and Ra from the analysis and researches of the soil environment quality is evaluated by geoaccumulation index; the soil environment quality safe is evaluated by the Nemero Index and the quality ranks from Rate II to Rate III.5. In accordance with the comprehensive analysis of groundwater environmental quality and soil environment quality, the author concludes that the groundwater safety of the area is divided into safety, basic safety and unsafety. The groundwater at Jianshanzi is not safe, Dawantou and Chenjiagou, Mashangling and Taohuahe, Changsangbao, Yuanshanbao and Panguanmiao is basiclly safe; the other areas are safe. |
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