Characteristic of groundwater flows in Hotan River Basin:Isotope and hydrochemistry-based analysis
In order to study the groundwater transformation and runoff characteristics in Hotan River Basin,based on the hydrogeological survey and hydrochemical sampling,we applied SPSS mathematical statistics,Q-type cluster analysis,Gibbs method and simulation analyses to study the two typical profiles,combining with water chemical characteristics analysis and isotope(D,18 O,T and 14 C)tracing methods.The results showed that:1)From south to north(from high mountain areas to piedmont gravel plains,fine soil plains,and desert areas),groundwater runoff conditions are deteriorating.Total dissolved solids(TDS)gradually increase from 0.49g/L to 4.80g/L,and the hydrochemical type changes from HCO3·SO4-Ca·Na to Cl·SO4-Na.The main hydrochemical controls shift from water-rock interaction to evaporation-concentration.2)From the concealed fault at the mouth of the mountain range to the Gujiangbag Town,located 2.5km southwest of Hotan City,the groundwater is concurrently recharged by upstream lateral runoff and river water disjointed infiltration,exhibiting a rapid flow rate.TDS decreases from 1.8g/L in upstream to 0.6g/L,with ages＜100 years.Enroute to the Yingaireke Reservoir,surface water and groundwater undergo multiple mixing resulting in extremely complex transformation relationships between the two.To the north of the Yingaireke Reservoir,groundwater runoff slows down,with a wider age distribution mainly between 100 to 1000 years.3)In the downstream fine soil plain area,within the confined aquifer structure,the hydrochemical characteristics and runoff intensity vary significantly at different depths,shows a pronounced vertical differences.Taking a depth of 80m underground as the boundary,the groundwater runoff exhibits rapid velocities,low TDS values,and young ages in the upper shallow zone.Conversely,it displays slower velocities,higher TDS values,and older ages in the lower deep zone.Hydraulic connectivity between the two part is weak,with only partial overflow recharge relations.4)In inter-river blocks,groundwater flows from the watershed to both sides.Groundwater on the eastern side flows towards the west bank of the Yurungkax River,while on the western side it flows towards the east bank of the Karakash River.After receiving lateral inflow and river water infiltration recharge,groundwater flows northeast towards Hanggui Town in Lop County and northwest towards Kuiya Town in Karakax Count,and finally discharge into surrounding desert areas.The research results can provide theoretical and technical support for the sustainable development and utilization of groundwater resources and ecological environmental protection in Hotan River Basin.
groundwater circulationisotopeshydrochemistrytypical sectionHotan River Basin
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