In this paper

we evaluated the variations of soil water and explored the suitability of the soil water characteristic curve fitting model in interdune lowland at the southern edge of Gurbantunggut Desert. Using the pressure membrane apparatus

we measured the soil water characteristic curves at different soil depths (0—150 cm) in desert land. Combined with bulk density

grain size and saturated water content

the distributions of soil water characteristics and pore size in different soil layers were analyzed

and the applicability of Gardner model and van Genuchten model fitting was defined. Our data showed that the sandy soil release rate varied regularly with soil water suction rate in interdune lowland. Soil water characteristic curves in different soil layers showed a steep trend and strong water release in low suction range (0~100 kPa)

while they presented a smooth and slow trend

with a high water holding ability in high suction range (100~1 500 kPa). The soil moisture characteristic curve was consistent with its physical properties. The distribution of soil pore size varied regularly

with increasing the proportion of large pores from the top to the bottom soil layer and the small pores held the biggest ratio in 20—40 cm soil layer

which was conducive to the rapid infiltration of the spring snow melt into the soil. In addition

our results found that both the two models fitted well with the measured data in this region. The VG model was better than G model in fitting the soil water characteristic curve in interdune lowland

but G model was simple in form

with few parameters and easy solving

which was much more convenient for practical application.