Hydrochemical Characteristics And Influencing Factors Of Reservoirs Under Different Environmental Background In Shiyang River Basin

As an important part of global water resources,reservoir water resources have a profound impact on the production and life of the surrounding human beings.The reservoir plays an important role in the utilization and development of water resources,such as river runoff regulation,flood storage,irrigation and power generation.The reservoir in arid area is an important part of surface water resources in the basin,which interacts with the surrounding sedimentary background,climatic conditions,environmental factors,human society,etc.As an arid area with a large population density in the world,the water resources shortage and water environment problems in Shiyang River Basin have been concerned.The reservoir in the basin is an important source of water for industrial and agricultural production and ecological environment protection in Wuwei basin and Minqin oasis.The water environment security of the reservoir directly affects food security and human health.In this study,representative reservoirs in Shiyang River Basin are selected as the research object.Based on the water samples of three representative reservoirs in mountain area,oasis area and desert area of Shiyang River Basin from June 2015 to Aug 2019,the spatiotemporal differentiation of reservoir water chemistry characteristics under different environmental background are analyzed and discussed.This paper analyzes the hydrochemical characteristics of reservoir water bodies in different environmental backgrounds?mountain area,oasis area,desert area?of Shiyang River Basin,the process of ion migration,dilution,enrichment and influencing factors of surface water bodies in the basin,and systematically explores the differences of hydrochemical characteristics between reservoirs in arid area under the influence of human activities It is expected to provide more scientific theoretical support for the macro-control,utilization and development of water resources and the sustainable development of water environment and ecological environment.The main conclusions of this study are as follows:?1?The regional differences of hydrochemical characteristics of reservoirs in Shiyang River Basin are relatively significant.The hydrochemical characteristics of Nanying Reservoir,Hongyashan Reservoir and Qingtu Lake are Ca-HCO₃,Ca?Mg?-HCO₃ and Na-SO₄?Cl?,respectively.The data of some samples at the end of the basin have shown the characteristics of salt water.?2?The overall ion content of the reservoirs shows the characteristics of Nanying Reservoir<Hongyashan Reservoir<Qingtu Lake.From mountain area to oasis area and desert area,the ion concentration of water body increases gradually.The main cations in the water changed from Ca²⁺to Na⁺,and the main anions changed from HCO₃^-to SO₄^2-.There are also seasonal differences in the total amount of ions in three reservoirs in Shiyang River Basin:the total amount of ions in the upper reservoir in winter and spring is slightly higher than that in summer and autumn,and the total amount of ions in the middle and lower reservoir in summer and autumn is higher than that in winter and spring.The strong evaporation in arid area also leads to the phenomenon that the peak period of ion concentration moves backward in time scale.?3?There are obvious regional differences in the influencing factors of hydrochemical characteristics of different reservoirs in the basin.Rock weathering is the key driving factor for the change of hydrochemical characteristics of reservoirs in Shiyang River Basin,and evaporation crystallization also has a certain impact on the hydrochemical characteristics of reservoirs.The process of rock weathering and sedimentary background are the main control factors of water chemistry of Nanying Reservoir,and precipitation in mountainous area will also affect the water chemistry characteristics of Nanying Reservoir;rock weathering and evaporation crystallization are the common control factors of water chemistry characteristics of Hongyashan Reservoir and Qingtu Lake.?4?The influence of the reservoir on the spatial allocation of water resources greatly affects the process of ion migration,dilution and enrichment of surface water,which may change the natural water cycle process of the inland river basin,and the impact of this change is unknown.The later research should focus on the influence of the reservoir on the surface water environment characteristics and water cycle process in the middle and lower reaches of the arid basin.