The Study On Groundwater Cycle Model Of Lucaogou Basin In Yili,Xinjiang

The Lucaogou Basin is located in the western part of the Central Asian Water Tower,lied in the northeastern part of the Huocheng Plain and situated in the northwest of Yili Basin.The meteorological and hydrological conditions in the region are unique for it's"Island Effect"to the typical arid region in the northwest of China.The tectonic movement of the Tianshan tectonic belt piedmont has constructed complex hydrogeological conditions of the Lucaogou basin.At the same time,the abundant groundwater resources in the area also play an important role on the Lucaogou Basin and the Huocheng Plain's environment.However,due to the rapidly economic development in recent years,the water demand is going exacerbated,human agricultural production activities are also affecting the region's groundwater circulation go further.Therefore,it is much necessary to carry out the research on the groundwater circulation model in the Lucaogou basin.This study could not only helps understand the groundwater circulation pattern in the basin,but also provides basis for the development and utilization of groundwater resources of the area.The project is based on the project of the Geological Survey Center of Xi'an,China Geological Survey--"1:5,000 hydrogeological survey in the western plain of Yili River Valley".Putting the Lucaogou Basin as the main research area,we carry out the investigation about isotope hydrochemical spatiotemporal variation characteristics,groundwater system division and groundwater cycle characteristics of different water bodies by analyzing hydrogeological conditions,the characteristics of hydrochemistry,isotopic characteristics and hydrodynamic conditions of different water bodies.Moreover,the groundwater circulation model of the Lucaogou basin is revealed.Specific research results are as follows:?1?The aquifer structure in the study area are single thick structure from the upper reaches and become into the double-layer structure in the middle reaches and at last turn out to be multi-layer and inter-layer structure in the down reaches.In the upper reaches,the surface water system basically control the development of aquifer structure.The aquifer structure in the middle reaches is controlled by the hydrodynamic conditions and the uplift of the Tertiary strata of the basement,presented as the thickness of the aquifer relatively got thinner and the appearance of double-layer structure.In the down reaches area,different aquifers are mixed with each other so that the aquifer structure appear multi-layer and inter-layer,and the thick of clay layer increased.?2?The analysis on the different water bodies'hydrochemical temporal and spatial characteristics of the study area show:the content of water ions in the wet season is higher than it is in the dry season,and the content of those ions increases from upper reaches to down reaches.The regional TDS in the upper reaches is 100³00mg/l,and HCO₃-Ca and HCO₃-Ca·Mg are the water chemistry types mainly.The middle reaches'TDS range is 200⁵00mg/l,the water chemistry types become what HCO₃-Ca·Mg and HCO₃·SO₄-Ca·Mg are main type.In the downstream area,the range of TDS are400¹000mg/l.The results of hydrogeochemical evolution show that the water bodies in the study area are mainly affected by rock and evaporation,and a series of dissolution and ion exchange processes occur during the migration of groundwater.?3?The local precipitation line in the study area is y=8.35x+12.82,the evaporation line is y=5.73x-15.06,and the hydrogen and oxygen stable isotopes of all water bodies are located above the precipitation line and close to the local evaporation line,which indicating that the water in the study area are mainly from the mountainous areas and the ice-snow melt-water that affected by evaporation.The hydrogen and oxygen stable isotopes of the water bodies are relatively rich in the wet season.The hydrogen and oxygen isotopes of the springs are relatively poor relative to other water bodies.?4?Based on the analysis of the characteristics of water chemistry,isotopic characteristics and groundwater distribution in 2013,2015 and 2016 of the study area,we divide the Lucaogou Basin into Yichegashan groundwater system,Daxigou groundwater system,Dadonggou groundwater system,Guozigou groundwater system and Saarbulake groundwater system.?5?The groundwater of Lucaogou Basin is mainly supplyed by large area of farmland irrigation water and the river water mixed of the meteoric water,mountainous precipitation and ice-snow melt-water.The groundwater received from the northeast flow firstly to the southwest direction and then turned to be the southward flow.Affected by the Tertiary strata's uplift and aquifer multilayer structure,there are a large number of springs group excreting the groundwater.Then the spring group pooled for the spring river supplying to groundwater during the flowing process to the downstream.Groundwater continues to run southward until it flows out of the basin finally.Compared with other basins,the Lucaogou Basin has some commons and differences at the same time.It has its own unique groundwater circulation pattern.