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Three‐dimensional volume‐averaged soil moisture transport model with a scalable parameterization of subgrid topographic variability
Author(s) -
Choi Hyun I.,
Kumar Praveen,
Liang XinZhong
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005134
Subject(s) - moisture , flux (metallurgy) , water content , environmental science , scale (ratio) , curvature , soil science , geology , atmospheric sciences , meteorology , mathematics , geotechnical engineering , geometry , physics , materials science , metallurgy , quantum mechanics
Subgrid variability of subsurface moisture flux transport is strongly influenced by the local variation of topographic attributes, such as elevation, slope, and curvature. A three‐dimensional volume‐averaged soil moisture transport (VAST) model is developed to incorporate these effects using the volume‐averaged Richards equation. The small‐perturbation approach is used to decompose the equation into mean and fluctuation, which are then averaged over the model grid box. This formulation explicitly incorporates the variability of moisture flux due to subgrid variation of topographic attributes. The model is independent of scale, but the parameters need to be estimated at the model scale. It is demonstrated that the flux contribution from the subgrid variability can be comparable to that of mean flux, particularly under drier moisture conditions. This formulation can be substituted for subsurface moisture transport schemes in most existing land surface models.