Impact of precipitation on soil moisture in seasonal drought regions in Southwest China
2024
ZHANG Manxue | LUO Houpan | CHEN Chuan | YU Kangning | CHEN Taiyang | HUANG Rong | LIU Zhandong
【Objective】 Soil water is not only a resource to plants but also controls microbial activity and biogeochemical processes which are essential for ecosystem functions. Its spatiotemporal dynamics is controlled by a multitude of biotic and abiotic processes. In this paper, we investigate the response of soil water dynamics to rainfall events in the seasonal drought regions in Southwest China. 【Method】 The study was based on in-situ observations and rainfalls and soil water content measured from April to October 2023 across the region. Using these data, we analyzed the response of soil water content in paddy and corn fields to rainfall events with different intensities. 【Result】 ① Rainfall intensities affected penetration depths of the rainfall water. Rainfall events less than 2 mm/h affected the soil water mainly in the 0-20 cm soil layer, while rainfall events with intensity greater than 2 mm/h but less than 8 mm/h affected soil water in the 0-50 cm soil layer. ② The responses of soil water to rainfall events varied with crops. For the corn and paddy fields, the mean effective recharge efficiency were 0.72%/h and 1.07%/h, the mean effective recharge lag time were 0.88 h and 5.38 h, and the mean regression rates were 0.04%/h and 0.02%/h, respectively, during the experimental period. ③ Compared with the corn fields, the paddy fields were more sensitive to rainfall, probably due to the difference in canopy interception of the crown leaves and water uptake of the roots between the two crops. The initial soil water content also affected the response of soil water to rainfall events. 【Conclusion】 Heavy rainfall events can effectively recharge soil water. Irrigation is needed for both crops during dry periods or periods in which rainfalls were less than 2 mm/h.
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