| Lijiang city is located in the northwest of Yunnan province, Lijiang ancient city is China's famous historical and cultural city and tourist scenic spot. In Lijiang city, there are mainly three springs: Heilongtan springs, Qingxi springs and Guchengqu springs. The three springs is a major source of the ancient city water, which were used as domestic water, landscape water and service water. In recent years, Heilongtan springs occurred irregular cutoff, and the cutoff frequency is getting bigger and bigger. The cut-off of Heilongtan springs had seriously affected the production, life and the travel quality, which lead to restrictive effect on the social and economic development of Lijiang city. Therefore, Lijiang city launched Heilongtan springs protection project. Heilongtan springs protection project is filling water in the domain recharge area, Then Heilongtan Springs accept recharge through the leakage, which is based on the feasibility analysis of hydrogeological conditions. However, when Heilongtan springs cut-out, the Qingxi springs flow only slightly decreased, which is higher than its export about 11 m. Guchengqu springs, which below the water level of Heilongtan springs, is still gush from the export and flow stability.In order to find out these phenomenon as well as understand why the Heilongtan spring cut-off, and provide theoretical basis for springs protection project. Based on the drainage characteristics of the three springs. This paper use the back tracking method deeply analyze the groundwater dynamic feature, analysing the relationship between the springs discharge and the rainfall, the groundwater level, and further analyze the groundwater chemistry characteristics by using the software SPSS, the gray correlation method and the hydrogeochemical modeling software PHREEQC. Based on the ?D and ?18O value of the rainfall, this paper calculated the supply altitude of the spring groups. Using the water cycle the deuterium excess result, this paper get the isotope feature. Then, based on all the research metioned above, this paper deeply study the subsystem of the spring system, and explain the reason of the flow character difference between the Qingxi springs and the Guchengqu springs. Finally, Based on the system research, analyze the feasibility of the spring protection engineering.Through the studies above, the following results and conclusions have been obtained:?1?The recharge area of Heilongtan spring karst-water system is northern carbonate formation and karst plateau basin, its` altitude is 2600-3500 m.From Heilongtan to recharge area, limestone formation?T2b? is continuous distribution. By connecting test, it determine that Jiuzihai and the southern three springs` connecting relation is exist, which explains the three springs get groundwater`s recharge in Jiuzihai.?2?The relation between the discharge of Heilongtan and rainfall change is close, Heilongtan springs peak flow lagged peak rainfall about 3 to 5 months. Qingxi springs peak flow had no remarkable relation to rainfall, spring flow only slightly decreased at low rainfall years. This shows that the main recharge source of Qingxi springs and Heilongtan spring is different, in addition to Jiuzihai, Qingxi springs mainly get groundwater recharge from more far-reaching and stable place.?3? Analyze the correlation of various spring water samples of hydrochemistry ion concentration by using SPSS software, the results shows that Ca2+ and Mg2+, Ca2+ and HCO3-, Mg2+ and HCO3- are significant correlation. It shows that the groundwater constantly dissolved calcite, dolomite and gypsum when it flow in the carbonate formation. Analyze the correlation of spring water macro elements by the Gray Relational Analysis, the result show that southern springs have obvious correlation with Jiuzihai, Heilongtan springs have highest correlation and Qingxi springs have lowest correlation among them. Using PHREEQC software for water chemistry inverse modeling of springs groundwater runoff path, the results show that Jiuzihai karst groundwater and Heilongtan springs,Qingxi springs, Guchengqu springs have hydraulic connection and supply-discharge relationship.?4? In addition to Qingxi springs, hydrogen and oxygen isotopic composition of the six groups karst water basic fall on the rain line, it reflects that the recharge source of karst water is mainly comes from atmospheric precipitation in the research area. According to the calculation of recharge elevation and theinstructions of excess deuterium, we can know that Heilongtan springs, Qingxi springs, Guchengqu springs exists obvious difference. According to the tritium dating, Heilongtan springs` age is about 4 to 5 months, while Qingxi springs` formation age is more than 12.43 years, it shows that in addition to Jiuzihai, Qingxiquan also accept melted snow water supplies which has the far-reaching path, the longer circulationand replacement time.?5? In-depth analysis Heilongtan springs and Qingxi springs system, we can know that they belong to different groundwater flow subsystem. In addition to Jiuzihai, Qingxi springs get snow melt water supplies, it belong to multi-source supplication with a discharge. Heilongtan springs mainly accept Jiuzihai supplies, it belong to monophyletic supplies with a discharge. As a result, when Heilongtan springs cut-out, the higher Qingxi springs` flow only slightly decreased. Based on the analysis of groundwater system, filling water at Jiuzihai areais feasible. |
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