Water Retention Curves of Soils in Linzhi of Tibet Plateau

LI Yuqing; MENG Qiang; ZHANG Cun; ZHANG Wenxian

doi:10.13522/j.cnki.ggps.2017.10.014

Abstract：The genesis of soils in Tibetan plateau differs from those in other areas and knowing their hydraulic properties is critical in understandinghydrological cycle in the plateau. In this paper we measured the hydraulic properties of a number of intact soil samples and evaluated how well the van Genuchten model and the Gardner-Russo model can fit these water retention curves. In particular, twenty-four undistributed soil samples were taken-from hulless barley fields in Milin, Bayi and Nyingchiat altitude of 2905 m, 3240 m and 3879 m, respectively in Linzhi. The results show that within the matric potential of-11.0 kPa to-4.0 kPa ,-42.0 kPa to-11.0 kPa and-54.0 kPa to-42.0 kPa, the average change of water content with matric potential was 5.4 × 10-3 cm3/(cm3 · kPa), 11.2×10-3 cm3/(cm3 · kPa) and 6.7×10-3 cm3/(cm3 · kPa), respectively. The maximum variance of the measured water retention curves was within the matric potential of-54.0 kPa to-42.0 kPa. The water retention curves of different soils depend on their clay content, while their variability depends on the content of sand. The mean and maximum relative errors of the results predicted by the van Genuchten formula were 0.04 and 0.09 respectively, whereas for the Gardner-Russo formula, these errors were 0.06 and 0.14, respectively. For the soils investigated in this paper, the van Genuchten formula is superior to the Gardner-Russo model.