Change in Evaporation from Soil as Affected by Irrigation at Different Freeze-thaw Stages
2022
PAN Daquan | CHEN Junfeng | XUE Jing | CUI Lihong | ZHAO Dexing | DU Qi
【Background and Objective】 Seasonal permafrost is widely distributed in north China and water evaporation from such soils depends on both soil water content and freeze-thawing process. In this paper, we experimentally studied the change in evaporation with irrigation at different stages of the freeze-thawing process. 【Method】 The experiment was conducted in a field; a bare plot without irrigation was taken as the control (CK). The treatments were to irrigate the 225 m3 per hm2 of water at different freeze-thaw stages, which were represented by L1—L7. Evaporation from the soil in all treatments was simulated using the heat-water model (SHAW). 【Result】 Irrigation during the freeze-thaw period increased the cumulative soil evaporation by 24.0%~150.0%, compared with the CK. Irrigation during the unstable freezing stage enhanced evaporation, and compared with CK, it increased the cumulative evaporation by 22.4%~27.0%. Irrigation during the stable freezing stage affected evaporation the least, especially L3 and L4 treatments, where the evaporation was 3.8%~67.1% lower than that in other treatments. Irrigation during the thawing period led to the highest cumulative evaporation, increasing by 55.3%~97.1%, compared with other treatments. 【Conclusion】 Irrigation during the unstable freezing and thawing stages increased evaporation greatly and should be avoided. In contrast, irrigation during the stable freezing stage affected evaporation the least in the first 3 days after the irrigation. Irrigation during the freeze-thaw period could result in 8.6%~9.3% of the irrigating water lost via evaporation.
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