Study On The Conversion Mechanism Of Surface Water And Groundwater In The Middle And Lower Reaches Of Cherchen River In Xinjiang

Cherchen river basin is located in the southern edge of the tarim basin,the climate perennial drought and little rain.The surface water and groundwater resources are relatively scarce,which is the water supply guarantee for people,livestock,industrial and mining enterprises as well as the irrigation oasis.As is known to all,the protection of ecological environment in arid areas is closely related to the sustainable development and the rational and optimized management of water resources,so it is particularly important to strengthen the research on the conversion of surface water and groundwater.Taking qiemo river middle and lower reaches area as the study area,full analysis of the conditions of the study area geology,climate,hydrological condition,hydrogeological condition and artificial factor under the influence of groundwater flow characteristics,combining the predecessors of the existing research results,on the groundwater system theory as a guide,combined with environmental isotope method,numerical simulation of groundwater and hydrogeochemical method,comprehensive analysis to explore Ju Mo qiemo river on different geomorphic units of groundwater and surface water transformation relationship,and reveal its water circulation characteristics.The main results are as follows:(1)under the control of geological and geomorphic conditions,the groundwater circulation in cherchen basin is a cycle mode of"middle mountain--alluvial and pluvial plain—valley plain—aeolian desert",and the groundwater of surface water has undergone three transformations.The middle and high mountain area is the formation area of water resources in the basin,which has completed the first transformation of meteoric precipitation and groundwater.In the alluvial-diluvial plain area in front of the mountain,the river water is separated from the groundwater,and the river water penetrates into the groundwater surface through the thick vadose zone to replenish the groundwater,forming the second mutual transformation process between surface water and groundwater.The valley plain area is located in the village of agele-lekkoomu.Affected by climate change and human factors,the transformation relationship is complex.However,the overall transformation from groundwater to surface water is presented,and the river water and groundwater are not separated,forming the third mutual transformation process between surface water and groundwater.The eolian desert area is located at the northern boundary between tattijan township and the research area.(2)According to the isotopic characteristics of surface water and groundwater,both river water and groundwater in the study area originated from meteoric precipitation and glacial snow melt water in the southern high mountain areas.After the passage of the river,the disjointed belt of the alluvial plain in the south recharged the groundwater by infiltration,and the groundwater overflowed and mixed with the surface water near the village of agele.The anthropogenic influence on the conversion of surface water and groundwater is obvious in the irrigated area,which generally shows that the river discharge groundwater,irrigation backwater infiltration recharge groundwater is significant,and the groundwater is also replenished by the lateral runoff of the adjacent aquifer.The desert area is formed by the east wind in the lower lekkoomu,the groundwater is shallow and the groundwater is discharged by the river.The conversion rates of groundwater and surface water were 61.5%,40.5%and 23.7%,respectively,in the three conversion sections at the eastern boundary of the research area.(3)The hydrochemical characteristics among the water bodies in cherchen basin show significant differences with the changes of geomorphic units.The river runoff in the study area is fast,and the hydrochemistry type gradually evolves from Cl·HCO₃·SO₄-Na·Mg type water to Cl·SO₄-Na type water.According to Gibbs diagram,alluvial and diluvial plain areas and valley plain areas are mainly affected by rock weathering,while eolian desert areas are significantly affected by evaporation.The water chemistry type of diving is HCO₃·Cl-Na type water in the upstream,which gradually evolves into Cl·SO₄-Na·Mg type water in the irrigated area,which is mainly affected by evaporation and rock weathering.In the east of tatigan,the groundwater gradually changes from dissolving filtration to being mainly affected by evaporation and concentration,and the chemical type of diving water evolves into Cl·SO₄-Na·Mg and Cl·SO₄-Na type water.The hydrochemical types of artesian water showed a trend of evolution from Cl·SO4·HCO₃-Na·Mg water to Cl·SO₄-Na·Mg water.The variation of TDS and cl-concentration of surface water and groundwater further proves the relationship between surface water and groundwater in different geomorphic units^[1].Groundwater runoff to agele township,the river water and groundwater surface water and groundwater mix,the irrigated area water body is affected by human,the overall performance is groundwater recharge surface water;Aeolian desert area,groundwater buried depth recharge river water.(4)Based on the isotopic characteristics of meteoric precipitation in urumqi and hetian stations,the local meteoric precipitation lines were drawn.The isotopic characteristics of surface water and groundwater in the study area indicated that both river water and groundwater originated from meteoric precipitation and glacial snow melt water in the southern high mountain area.After the passage of the river,the disjointed belt of the alluvial plain in the south recharged the groundwater by infiltration,and the groundwater overflowed and mixed with the surface water near the village of agele.The anthropogenic influence on the conversion of surface water and groundwater is obvious in the irrigated area,which generally shows that the river discharge groundwater,irrigation backwater infiltration recharge groundwater is significant,and the groundwater is also replenished by the lateral runoff of the adjacent aquifer.The desert area is formed by the east wind in the lower lekkoomu,the groundwater is shallow and the groundwater is discharged by the river.The conversion rates of groundwater and surface water were 61.5%,40.5%and 23.7%,respectively,in the three conversion sections at the eastern boundary of the research area.