2021 Volume 77 Issue 2 Pages I_229-I_234
The purpose of this study is to clarify whether terrestrial water cycle variables can be better represented by improving water retention curve and considering horizontal and vertical distribution of soil hydraulic parameters in a land surface model. The hydraulic function of a land surface model ILS was changed from Clapp and Hornberger (CH) model to observation-based van Genuchten (VG) model. Horizontal and vertical variability of soil hydraulic parameters were estimated globally at 0.5 degree resolution using the latest soil dataset and a machine learning-based pedotransfer function. The improvement of the soil scheme resulted in an increase in the coefficient of determination of estimated soil moisture from 0.45 to 0.54, as well as an improvement in runoff and river discharge. The change in the hydraulic function to VG model improved the accuracy of estimation, especially for sandy soils, due to the increased water holding capacity of the soil. Other hydraulic variables such as runoff and river discharge are better represented as well, which is expected to contribute to the improvement of accuracy of terrestrial hydrodynamic modeling.
PROCEEDINGS OF HYDRAULIC ENGINEERING
