Daytime and nighttime groundwater contributions to soils with different surface conditions

Xing, Xuguang; Ma, Xiaoyi; Shi, Wenjuan

Daytime and nighttime groundwater contributions to soils with different surface conditions | Contributions diurnes et nocturnes des eaux souterraines aux sols pour différentes conditions de surface Contribuciones diurna y nocturna de agua subterránea a los suelos con diferentes condiciones en la superficie 不同地表条件下白天和晚上地下水对土壤的贡献 Contribuição diurna e noturna das águas subterrâneas para solos com diferentes condições superficiais

2015

Xing, Xuguang | Ma, Xiaoyi | Shi, Wenjuan

Contributions of groundwater to the soil-water balance play an important role in areas with shallow water tables. The characteristics of daytime and nighttime water flux using non-weighing lysimeters were studied from June to September 2012 and 2013 in the extremely arid Xinjiang Uyghur Autonomous Region in northwestern China. The study consisted of nine treatments: three surface conditions, bare soil and cotton plants, each with water tables at depths of 1.0, 1.5, and 2.0 m; and plastic mulch with a water table at 1.5 m but with three percentages of open areas (POAs) in the plastic. The groundwater supply coefficient (SC) and the groundwater contribution (GC) generally varied with surface conditions. Both SC and GC decreased in the bare-soil and cotton treatments with increasing depth of the groundwater. Both SC and GC increased in the plastic-mulch treatment with increasing POA. Average nighttime GCs in the bare-soil treatments in July and August (the midsummer months) were 50.8–60.8 and 53.2–65.3 %, respectively, of the total daily contributions. Average nighttime GCs in the cotton treatments in July and August were 51.4–60.2 and 51.5–58.1 %, respectively, of the total daily contributions. The average GCs in June and September, however, were lower at night than during the daytime. Soil temperature may thus play a more important role than air temperature in the upflow of groundwater.

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