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China University of Geosciences (2020)

Groundwater Flow Patterns and Numerical Simulation of Typical System in an Arid Inland Basin,Northwest China


Titre : Groundwater Flow Patterns and Numerical Simulation of Typical System in an Arid Inland Basin,Northwest China

Auteur : 王建军;

Grade : Doctoral Dissertation 2020

Université : China University of Geosciences

Résumé partiel
Manas River Basin is a typical mountain-oasis-desert arid inland river basin in Northwest China.As one of the biggest irrigation area in Xinjiang,mulch drip irrigation technology has been applied in the Manas River Basin.Now the Manas River Basin has become the key base of ecomonic development in Xinjiang.Rapid population and agricultural growth have been achieved through the heavy utilization groundwater during the past fifty years.Large-scale groundwater exploitation has caused many eco-environmental problems,such as soil salinization,land subsidence,and groundwater quality degradation.Understanding the various groundwater flow pathways from recharge to discharge is critical for sustainable utilization of groundwater resources and maintaining ecosystems.Based on the geological and hydrogeological conditions,the groundwater flow patterns under natural condition and human activities have been analyzed by using hydrogeochemistry,environmental isotopes,Bromide tracer tests and numerical simulation in the Manas River Basin.The major conclusions of this research are as follows.Three groundwater flow patterns(local,intermediate and regional flow patterns)are identified in the Manas River Basin under natural condition.In the piedmont plains,local groundwater flow systems contain modern water residence times younger than 50years.Groundwater velocities in this region are greater than 0.5 m/d.The groundwater is characterized by the type of HCO3·SO4-Ca with TDS lower than 400 mg/L.In the oasis plains,precipitation and evaporation are considered as recharge source and groundwater discharge,indicating that local flow systems operate.The groundwater residence times are between 50 and 180 a.The intermediate and regional flow systems contain groundwater residence times between 10 and 30 ka in the deep aquifers across the whole basin,with groundwater type from HCO3·SO4-Ca in the recharge area to Cl-Na in the discharge area.Among these two systems,groundwater velocities are lower than 0.05 m/d.Soil flow systems operate with irrigation water providing a highly evaporated recharge source under mulch drip irrigation in the oasis plains.Intermediate and regional flow systems have been changed into mixing flow patterns under human activities.Intense groundwater pumping has caused the groundwater to leak from shallow and deep aquifers to intermediate aquifers.This results in the mixing patterns of exploitation,irrigation and infiltration

Mots clés : Manas River Basin; Human activities; Groundwater flow patterns; Bromide tracer; Numerical simulation;

Présentation (CNKI)

Page publiée le 15 juin 2021, mise à jour le 22 octobre 2021