Premium
Predicting subgrid variability of soil water content from basic soil information
Author(s) -
Qu W.,
Bogena H. R.,
Huisman J. A.,
Vanderborght J.,
Schuh M.,
Priesack E.,
Vereecken H.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062496
Subject(s) - pedotransfer function , water content , soil texture , environmental science , soil science , soil water , water flow , geology , geotechnical engineering , hydraulic conductivity
Knowledge of unresolved soil water content variability within model grid cells (i.e., subgrid variability) is important for accurate predictions of land‐surface energy and hydrologic fluxes. Here we derived a closed‐form expression to describe how soil water content variability depends on mean soil water content ( σ θ (< θ >)) using stochastic analysis of 1‐D unsaturated gravitational flow based on the van Genuchten‐Mualem (VGM) model. A sensitivity analysis showed that the n parameter strongly influenced both the shape and magnitude of the maximum of σ θ (< θ >). The closed‐form expression was used to predict σ θ (< θ >) for eight data sets with varying soil texture using VGM parameters obtained from pedotransfer functions that rely on available soil information. Generally, there was good agreement between observed and predicted σ θ (< θ >) despite the obvious simplifications that were used to derive the closed‐form expression. Furthermore, the novel closed‐form expression was successfully used to inversely estimate the variability of hydraulic properties from observed σ θ (< θ >) data.