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Chang’an University (2019)

Study on Groundwater Recharge from Irrigated Lands in Xinjiang Based on Stable Isotope


Titre : Study on Groundwater Recharge from Irrigated Lands in Xinjiang Based on Stable Isotope

Auteur : 宋浩;

Grade : Master’s Theses 2019

Université : Chang’an University

Résumé partiel
Xinjiang Uygur Autonomous Region is located in the arid area of Northwest China,with little rainfall and strong evaporation.Agricultural development in arid area often requires groundwater irrigation to meet the needs of crop growth.Unreasonable exploitation and utilization of groundwater resources often leads to many environmental problems.In order to improve the irrigation efficiency of groundwater,it is urgent to explore the infiltration and migration regularities of soil water in vadose zone of arid area.As a key link between surface water and groundwater,the study of water movement in vadose zone has always been a hot issue in groundwater science.Hydrogen and oxygen stable isotopes can move with water,and can characterize water infiltration,evaporation and other processes.Therefore,stable isotope technology has become an important means to study water transport and exchange in vadose zone in recent years.In this paper,irrigation areas of Huocheng County(Yili Valley)and Shawan County(Manas River Basin)in Xinjiang were used as experimental sites.In order to study the effects of different lithological conditions and crop types on water migration in vadose zone,bare soil,desert and farmland were selected according to different site conditions(farmland includes corn field and cotton field according to different crop cultivation)as test sites.Field experiments were combined with laboratory experiments.Stable isotope techniques and numerical model were used to analyze soil water infiltration and migration regularities under different field conditions.On this basis,the irrigation infiltration recharge coefficients of each test site were calculated using stable isotope mass conservation method,water conservation method,fixed flux method and numerical model method.The following results were achieved :(1)In bare soil,desert,corn field,and cotton field,the moisture content of clay profile in the corn field was the largest before and after irrigation,and the stable hydrogen and oxygen isotopes enrichment of fine sand profile in the desert was the highest.Thereafter,on the basis of the hydraulic head curve,it is found that zero flux surface was formed at 40 cm,38 cm and30 cm in bare soil area,corn field and cotton field respectively.The isotope fractionation effect above zero flux surface was obvious,while the isotope in lower part was relatively stable ;Zero flux surface was formed at 40 cm and the isotope fractionation effect in upper and lower part of zero flux surface was obvious in desert,indicating that the isotope fractionation ability of the fine sand profile is stronger than of the clay profile under evaporation conditions.

Mots clés : stable hydrogen and oxygen isotopes; irrigation; isotope fractionation; infiltration recharge; evaporation;

Présentation (CNKI)

Page publiée le 26 mai 2020