Study On The Relationship Between Groundwater And Surface Water In Daihai Basin

Daihai Basin is located in the southwest of Ulanchabu City,Inner Mongolia Autonomous Region,with a drainage area of 2312.75km².It is in a semi-arid area.The rainfall in the area is naturally insufficient and accompanied by strong evaporation.With the reduction of water resources,the area of lake wetlands has decreased sharply.The ecosystem itself has poor resilience,and its ecological function is seriously degraded.In-depth research on the transformation relationship between surface water and groundwater in the basin,and the establishment of a water cycle model is a key link in solving ecological problems in the region.It can provide help for rational and scientific solutions to various water resources problems in the region in the future,and improve the improvement of similar lake wetlands.Provide scientific and technological support for ecosystem protection and restoration.This paper takes Daihai Basin as the research area,fully understands the topography and geomorphology,meteorological and hydrological,geological and hydrogeological conditions of the research area,as well as previous research results,and uses the theory of water cycle in the basin as the scientific methodology.The comprehensive analysis of water chemistry and hydrogen and oxygen isotope characteristics clarified and revealed the source of various water bodies in the basin and the transformation relationship between surface water and groundwater.The research results are as follows:(1)The replenishment source of each water body:atmospheric precipitation,the hydrogen and oxygen isotopic characteristics of surface water bodies and groundwater indicate that the atmospheric precipitation line equation in the Daihai Basin is:?D=7.434?¹⁸O+2.899(R²=0.9977),the surface water of the Daihai Basin Both groundwater and groundwater receive the replenishment of atmospheric precipitation,which infiltrates through the vadose zone to form soil water replenishment diving,and the surface water is recharged by groundwater outcrops and lateral runoff.(2)The transformation relationship between groundwater and surface water indicated by hydrogen and oxygen isotopes and water chemistry:Taking the Gongba River,a typical river in the region,as an example,mountainous rivers mainly receive basalt pores and fissure water,forming a spring river that flows into Shuanggucheng In reservoirs,the isotopic content of groundwater increased slightly,and groundwater replenished the river water;the hydrogen and oxygen isotope content of rivers in the plain area decreased,and the hydrogen and oxygen isotope content of groundwater increased slightly along the way,and the river water was recharged by groundwater.Daihai Lake is mainly supplied by the pore water of Quaternary loose rocks.(3)Hydrochemical characteristics and the water-rock interaction laws indicated:As the elevation decreases,the total dissolved solid content and conductivity of river water and groundwater gradually increase.The water chemical type of Gongba River is transformed from upstream HCO₃-SO₄-Ca type water to middle and downstream HCO₃-Ca-Na type water,spring water is HCO3-Ca type water,Daihai Lake water is Cl-Na water,and southern basalt cavern fissure water is HCO₃-Ca type water,the Quaternary loose rock pore water in the northeastern valleys,alluvial plains,alluvial plains and some lacustrine plains is HCO₃-Ca-Na type water,the lacustrine plain on the west side of Daihai Lake The pore water is HCO₃-Na type water and Cl-HCO₃-Na type water,and the Quaternary loose rock pore water in Liangcheng County and nearby areas is HCO₃-NO₃-Ca type water.The relationship of the main ion ratio indicates that the water chemical components of the water in the basin mainly come from the weathering and dissolution of silicate and carbonate.The Gibbs diagram of water chemistry shows that,except for lake water that is affected by evaporation,all other water bodies are affected by water and rock.(4)Water supply of Daihai Lake:The water of Daihai Lake is mainly recharged by atmospheric precipitation,river runoff into the lake and shallow groundwater.Calculated by the lake water isotope mass balance model based on the water balance method,the atmospheric precipitation recharge,river runoff recharge and groundwater The replenishment amounts are:22.64 million m³/a,7.209 million m³/a and 23.541 million m³/a,respectively,accounting for 42.41%,13.50%and 44.09%.