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| DOI：10.13522/j.cnki.ggps.2017.0378 |
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| Impact of Temperature on Soil Water Distribution under Irrigation from a Water Storage Pit |
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REN Rong, MA Juanjuan, ZHENG Lijian, CHENG Qiyun, GUO Xianghong, SUN Xihuan
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College of Water Resource Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Jinzhong University, Jinzhong 030619, China
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| Abstract: |
| 【Objective】 Water storage pit is a technique used in arid and semi-arid regions to save rainfall for reuse. This paper investigated the impact of temperature on soil moisture distribution under irrigation from a water storage pit. 【Method】 An apparatus was constructed to experimentally study water movement under irrigation from a water storage pit. During the experiment, we measured the wetting front and water content distribution. Different temperature combinations were examined. One was to keep the irrigation water temperature at 15 ℃ and vary soil temperature from 15 ℃ to 30 ℃, and the second one was to keep the soil temperature at 30 ℃ and vary the irrigation water temperature from 15 ℃ to 30 ℃. We also numerically simulated the redistribution of soil moisture when the irrigation water temperature was 15 ℃ and the soil temperature varied from 15 ℃ to 30 ℃. 【Result】 When the irrigation water temperature was a constant, the advancing distance of the wetting front in the radial and vertical directions increased by 18% and 4.4%, respectively, as the soil temperature increased. When the soil temperature was constant, the advancing distance of the wetting front in the radial and vertical directions increased by 2% and 1%, respectively, as the irrigation water temperature increased. The water content in the area beneath and adjacent the pit was high and as the temperature increased, this areas expanded. The accuracy of the simulated results depends on soil temperature, especially when the soil and irrigation water temperatures were contrasting. The maximum relative error between the simulated and measured values was as high as 19.87% when their temperature difference was 15 ℃. To ameliorate this, we proposed a modified method which can reduce the error by 4.76%. 【Conclusion】 Under irrigation from a single water storage pit, soil moisture redistribution was sensitive to temperature change in soil, and the model proposed in this paper could be used to predict how the water moves from the pit to the soil under different temperatures. |
| Key words: soil temperature; irrigation water temperature; numerical simulation; soil water distribution; water storage pit |
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