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| DOI：doi：10.13522/j.cnki.ggps.20190017 |
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| Autumn Irrigation Alerted the Geochemistry of Groundwater in Hetao Irrigation District：Take Yichang Irrigation District as an Example |
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HOU Kaixuan, YUE Weifeng, MENG Kaikai, YANG Ying, CHEN Aiping
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1.College of Water Sciences, Groundwater Pollution Control and Repair Engineering Research Center of Ministry of Education, Beijing Normal University, Beijing 100875, China；2.Yichang Experimental Station of Inner Mongilia Hetao Irrigation District, Wuyuan 015100, China
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| Abstract: |
| 【Objective】 Surface infiltration could change biogeochemical reactions in groundwater thereby alerting its chemical compositions. The aim of this paper is to investigate the responsive change in chemical composition of groundwater to infiltration following the autumn irrigation in irrigation districts. 【Method】 The experiment was conducted in Hetao Irrigation District, during which we measured the change in concentration of Na+, K+, Ca2+, Mg2+, SO42-, Cl-, HCO3- and CO32- and then statistically analyzed them. 【Result】 The irrigation increased the concentration of Cl-, SO42-, K++Na+, Mg2+ and HCO3-, but slightly reduced the concentration of Ca2+. The TDS was higher in south and lower in north of the irrigation district. The Piper diagram showed that the Cl-Na was the dominant groundwater type, accounted for 75% and 61% of the studied area before and after the irrigation respectively. Irrigation turned groundwater in 16.7% of the studied area to Mg-SO4-Cl type. The Gibbs model and ion proportional coefficient diagram revealed that the chemistry of groundwater in the studied region was mediated by evaporation, weathering and leaching of silicate and evaporite, and is independent of precipitation.【Conclusion】The mean TDS in the groundwater increased by 32.9% after the autumn irrigation, indicating the impact of soil leaching. Improving drainage after the autumn irrigation is hence essential. |
| Key words: Hetao Irrigation District; hydro-geochemistry analysis; Piper diagram; Gibbs diagram; autumn irrigation; groundwater |
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