## An Index for Degree of Hysteresis in Water Retention

#### Gebrenegus, Thomas and Ghezzehei, Teamrat A.

Soil Science Society of America Journal, volume 75(6), pp. 2122-2127 , 2011.

### Abstract

Direct characterization of hysteresis in water retention (WR) is typically cumbersome and time consuming. Thus, such data are scarce, and even when available are typically ignored in unsaturated flow modeling. One reason for disregard of this ubiquitous and significant feature of WR is lack of a universally applicable index for the degree of hysteresis that allows a priori assessment of its effect on flow. In this note we show that the mismatch between the hydraulic capacity functions of the primary drainage and imbibition curves can serve as generalized index for degree of hysteresis (H). Moreover, we showed that hysteresis indices of a broad range of soils are linearly related with the natural-logarithm of the van Genuchten n parameter (r^2 = 0.73). This model allows predicting the degree of hysteresis and the missing hysteresis branch using only wetting or drying water retention data. The robustness of the proposed index was illustrated by comparing it with error in simulated moisture redistribution in a horizontal column that arises from ignoring hysteresis.

## Citations

#### Cite as:

Gebrenegus, Thomas and Ghezzehei, Teamrat A., An Index for Degree of Hysteresis in Water Retention, Soil Science Society of America Journal, 75(6):2122-2127, 2011.

#### BibTex

@article{2011-Gebrenegus-Ghezzehei,
author = {Gebrenegus, Thomas and Ghezzehei, Teamrat A.},
date-modified = {2018-05-30 21:20:08 +0000},
doi = {10.2136/sssaj2011.0082N},
journal = {Soil Science Society of America Journal},
status = {published},
number = {6},
pages = {2122-2127},
researchgate = {https://www.researchgate.net/publication/274221936_An_Index_for_Degree_of_Hysteresis_in_Water_Retention},
sort-word = {method},
title = {An Index for Degree of Hysteresis in Water Retention},
volume = {75},
year = {2011},
bdsk-url-1 = {https://doi.org/10.2136/sssaj2011.0082N}
}