Comparison Of Groundwater Circulation Patterns In Typical Watershed Of Qaidam Basin

The Qaidam Basin is located in the northeast of the Qinghai Tibet Plateau,which is the first step on the ground.It is an important ecological barrier and transportation hub.The basin is rich in natural resources.It is the key area of economic construction in the West.With economic development and population growth,the problems of water supply contradiction and ecological environment in the basin are outstanding.Therefore,further research on the groundwater circulation pattern and evolution law in the basin and guiding the rational exploitation and utilization of water resources is the core problem to be solved in the sustainable development of the basin economy and ecology.Based on the series of projects carried out by the Xi'an geological survey center of the China Geological Survey around the economic construction and ecological civilization construction of the Qaidam national circular economy experimental area,the representative sections of four typical basins are selected on the basis of the analysis of previous research data,and the theory of groundwater flow system is referred to as the reference.Through geological and hydrogeological analysis,the groundwater circulation model of typical basin is depicted,and the evolution characteristics of groundwater flow system under different modes are revealed by numerical simulation of section and combined with water chemical isotope data,and the groundwater cycle model of typical basins is compared and analyzed,and the groundwater is followed by human activities.Suggestions for rational utilization of water resources are put forward.The main achievements of the study are as follows:1.The formation and evolution of water in the inland watersheds is the result of geological and geomorphological conditions,meteorological and hydrological factors and human activities.The geological and geomorphic conditions control the formation and distribution of groundwater,the heterogeneity of the aquifer medium controls the gradation of the groundwater flow system,and the groundwater and the atmosphere have strengthened the groundwater and the atmosphere.The coupling between the surface water system and the surface water system controls the intensity of groundwater recharge and discharge.Human activities have greatly changed the pattern,mode and intensity of the formation and evolution of natural conditions,making the underground hydrology process more complex and playing a leading role in the problem of modern water.2.The River groundwater from upstream to catchment center is controlled and influenced by geological structure,geomorphic features and aquifer lithology characteristics,and the multiple conversion of rivers and groundwater is completed.According to the characteristics of the River groundwater transformation,four kinds of groundwater transformation models are summarized.In the four mode,the gradation characteristics of groundwater flow system are mainly affected by the transformation of River groundwater.3.The difference of topography and sedimentary facies determine the difference of hydrodynamic conditions.Under the hydrodynamic drive of different gradation underground water systems,the groundwater chemical types show a horizontal and vertical distribution,showing different landscape patterns.Among them,the amount of water that participates in local underground water system circulation is the largest.4.The influence of human activity on groundwater circulation is mainly manifested in the transformation of groundwater recharge from linear or strip recharge to surface recharge,and the change of groundwater excretion from natural excretion to natural artificial excretion,with the decrease of groundwater resources and a series of ecological effects.5.The reduction of groundwater recharge resources will pose a greater threat to the health of the oasis ecosystem,which is maintained by the drainage of local groundwater systems.For the characteristics and utilization of water resources in the basin,it is suggested that agricultural irrigation should be used to reduce irrigation diversion and increase groundwater supply.