关键词: 
soil moisture /
HYDRUS-3D /
wetland /
quantitative simulation /
Sanjiang Plain

摘要: Different types of vegetation occupy different geomorphology and water gradient environments in the Sanjiang plain, indicating
that the soil moisture dynamics and water balance patterns of the different vegetation communities might differ from each other. In this
paper, a lowland system, perpendicular to the Nongjiang River in the Honghe National Nature Reserve (HNNR), was selected as the study
area. The area was occupied by the non-wetland plant forest and the typical wetland plant meadow. The Microsoft Windows-based finite
element analysis software package for simulating water, heat, and solute transport in variably saturated porous media (HYDRUS), which
can quantitatively simulate water, heat, and/or solute movement in variably-saturated porous media, was used to simulate soil moisture
dynamics in the root zone (20–40 cm) of those two plant communities during the growing season in 2005. The simulation results for soil
moisture were in a good agreement with measured data, with the coefficient of determination (R2) of 0.44–0.69 and root mean square
error (RMSE) ranging between 0.0291 cm3/cm3 and 0.0457 cm3/cm3, and index of agreement (d) being from 0.612 to 0.968. During the
study period, the volumetric soil moisture content of meadow increased with the depth and its coefficient of variation decreased with the
depth (from 20 cm to 40 cm), while under the forest the soil moisture content at different depths varied irregularly. The calculated result
of water budget showed that the water budget deficit of the meadow was higher than that of the forest, suggesting that the meadow is
more likely to suffer from water stress than the forest. The quantitative simulation by HYDRUS in this study did not take surface runoff
and plant growth processes into account. Improved root water uptake and surface runoff models will be needed for higher accuracy in
further researches.