| 基于水化学和同位素评价马莲河下游地下水补给河水的时空变化 |
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| 引用本文： | 王雨山,郭媛,周殷竹,李戍,王茜.基于水化学和同位素评价马莲河下游地下水补给河水的时空变化[J].干旱区地理,2020,43(2):290-298. |
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| 作者姓名： | 王雨山 郭媛 周殷竹 李戍 王茜 |
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| 基金项目： | 国家自然科学基金项目(41502259)；中国地质调查局项目(DD20160288，DD20190333）资助 |
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| 摘 要： | 准确评价地下水对河水的补给量是流域水资源量管理和合理利用的基础。在马莲河流域下游采集不同季节地表水和地下水样品75组，利用Cl-、电导率（EC）和D、18O同位素多方法联合评价，识别了地下水补给河水的位置、补给量及其季节变化。结果表明：马莲河水EC和Cl-质量浓度沿着流向均呈降低趋势，δD和δ18O值沿流向减小。雨季EC和Cl-质量浓度最低，δD和δ18O值最高。地下水各组分浓度均低于河水，时空变化不明显。地下水单宽排泄量存在时空变异，上段和下段为地下水强排泄区，中段地下水排泄较弱，不同季节地下水排泄量占总排泄量的72.20%～95.07%。雨季地下水单宽排泄量显著降低，河水中基流比例由雨季前期的68.89%降至29.43%。整体上，地下水补给河水季节变化明显，而空间变化规律较为稳定。研究成果有利于深入认识河水和地下水的相互作用机制，并为当地水资源利用提供基础依据。
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| 收稿时间： | 2019-05-12 |
Quantifications of spatial and temporal variations in
groundwater discharge into a river using hydrochemical and isotopic
tracers |
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| WANG Yu shan,GUO Yuan,ZHOU Yin zhu,LI Shu,WANG Qian.Quantifications of spatial and temporal variations in
groundwater discharge into a river using hydrochemical and isotopic
tracers[J].Arid Land Geography,2020,43(2):290-298. |
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| Authors: | WANG Yu shan GUO Yuan ZHOU Yin zhu LI Shu WANG Qian |
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| Abstract: | The Malian River,located in the southwestern portion
of the Ordos Basin,Inner Mongolia,China,is a secondary tributary of the middle
reaches of the Yellow River.It has experienced mounting pressure from
exploration and utilization of water resources,so the area has been facing
serious water shortages and deterioration of water quality.Finding accurate
ways to quantify groundwater discharge to the river is critical for protecting
and managing the water resources in the area.To study the spatial and temporal
variations of groundwater recharge,we collected 75 samples of surface water and
groundwater in the stretch of the river downstream of the Malian River during
pre monsoon,monsoon,and post monsoon seasons.A
multi tracer mass balance approach was applied to
identify the location,amount,and seasonal variations of groundwater
discharge.We used Cl- concentrations and electrical
conductivity in conjunction with oxygen and hydrogen isotopes.We observed
general decreases in Cl- concentrations(387.20-707.42
mg·L-1) and EC(1 705.40-3 123.60 μs·cm-1),as well as δ18O (-10.41‰--6.30‰) and δD
values (-78.25‰--54.88‰) as we moved downstream.The Cl- concentrations and ECvalues reached their minimum
values during the monsoon season,when δ18O and δD values peaked.All of the tracers
had lower concentrations or isotope ratios in the groundwater than they did in
the river water.Groundwater values included Cl- concentrations (115.92-255.96
mg·L-1),EC(409.58-196.84 μs·cm-1),δ18O (-11.19‰--9.11‰),and δD (-79.80‰--68.28‰).No evident spatial or temporal variations in
groundwater tracers were observed.All the groundwater samples had δD
and δ18O values close to the
Local Meteoric Water Line,indicating that groundwater was recharged by
precipitation and experienced limited evaporation.The river water was generally
more enriched in δD and δ18O,which may have resulted from evaporation.Groundwater discharge
rates varied spatially and temporally.Groundwater in the upper and lower
segments had much higher discharge rates (accounting for 72.20%-95.07% of the total) than that in middle
segment.The percentage of base flow in the river discharge was 68.89% during
the pre monsoon and 71.19% during the post monsoon season.Groundwater inflows decreased sharply during monsoon
season,with the ratio of base flow only accounting for 29.43% of the total
river discharge.In general,the seasonal variations in groundwater discharge to
the river were pronounced,while spatial variation was not evident.The extent of
interactions between river water and groundwater was mainly dominated by the
geological and hydrogeological settings and conditions,such as the aquifer
thickness,water hydraulic gradient,and riverbed permeability,so no spatial
variations related to the stable conditions in the downstream direction were
evident.Uncertainties remain in the model.However,when used correctly,a multi tracer method can be applied to provide detailed information on the
spatial distribution of groundwater discharge,especially in gaining rivers.This
study could provide a theoretical basis and technical support for better
understanding the interactions between river water and groundwater,as well as
the sustainable development of water resources and ecological and environmental
protection. |
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| Keywords: | groundwater discharge to river quantification spatial and temporal variations model the Malian River |
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