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| DOI：10.13522/j.cnki.ggps.2019363 |
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| The Impact of the Alternate Dry and Wet in Controlled Irrigation on Capillary Rise in Paddy Fields |
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XIA Chaofan, HONG Dalin, HE Yupu*, JI Renjing, RUI Xuqian,XIA Chaofan, HONG Dalin, HE Yupu*, JI Renjing, RUI Xuqian,XIA Chaofan, HONG Dalin, HE Yupu*, JI Renjing, RUI Xuqian,XIA Chaofan, HONG Dalin, HE Yupu*, JI Renjing, RUI Xuqian,XIA Chaofan, HONG Dalin, HE Yupu*, JI Renjing, RUI Xuqian
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State Key Laboratory of Hydrology-water Resources and Hydraulic Engineering, Nanjing Hydraulic Research Institute, Nanjing 210029, China
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| Abstract: |
| 【Objective】The purpose of this paper is to investigate experimentally the change in capillary rise and groundwater recharge in response to alternate dry and wet associated with controlled irrigation in paddy fields.【Method】The experiment was conducted in lysimeters with the depth of groundwater table kept at 0.5 m. During the experiment, we measured the change in groundwater recharge and soil moisture distribution, which was used to calculate evapotranspiration and capillary rise.【Result】Groundwater recharge peaked one day after irrigation or precipitation when soil moisture dropped to lowest level during a dry-wet cycle. The measured temporal change in groundwater recharge had multiple peaks during the growth season. The overall recharge was 253.98 mm, increasing by 244.65 mm compared the 9.33 mm recharge under flooding irrigation. About 51.1% of the evapotranspiration under controlled irrigation was due to the capillary rise from the groundwater. The soil moisture in depth below 30cm remained almost constant during the experiment due to the capillary rise from the groundwater, while the soil moisture in top 0~30 cm soil layer decreased as time elapsed.【Conclusion】Controlled irrigation increased capillary rise from groundwater in paddy field significantly, compared with flooding irrigation. More than half of the evapotranspiration under controlled irrigation originated from groundwater due to the increased capillary rise. The results presented in this paper are helpful for optimizing water management in paddy fields. |
| Key words: water-saving irrigation; paddy field; capillary rise; dry-wet alternation |
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