Response of forestland soil water content to heavy rainfall on Beijing Mountain, northern China

摘要

Continuous recording of precipitation and soil water content (SWC), especially during long periods of tor-rential rainfall, has proven challenging. Over a 16 h period spanning 21–22 July, 2012, Beijing experienced historic rainfall that totaled 164.4 mm. We used large lysimeter technology in four forested plots to record precipitation and variation in SWC at 10-min intervals to quantify the response of forestland SWC to heavy rainfall in a semi-arid area. Mean, maximum and minimum rainfall intensities were 23.4, 46.8 and 12.0 mm/h, respectively. Rainfall was concentrated in 2–6 mm bursts that accounted for 67.32%of the total rainfall event. Soil moisture conditions in this region are strongly dependent on patterns of precipitation. Water infiltration into 20, 40, 60, 80, 100, 120 and 160 cm soil layers required 1, 5, 20, 37, 46, 52 and 61 mm of precipitation, respectively, and to fully saturate these soil layers required 80, 120, 140, 150, 180, 200 and 220 mm of precipitation, respectively.