Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework

<p>Declining soil-saturated hydraulic conductivity (<span class="inline-formula"><i>K</i><sub>s</sub></span>) as a result of saline and sodic irrigation water is a major cause of soil degradation. While it is understood that the mechanisms that lea...

Full description

Bibliographic Details
Main Authors: I. Kramer, Y. Bayer, T. Adeyemo, Y. Mau
Format: Article
Language:English
Published: Copernicus Publications 2021-04-01
Series:Hydrology and Earth System Sciences
Online Access:https://hess.copernicus.org/articles/25/1993/2021/hess-25-1993-2021.pdf
id doaj-92ef2f18849140c690cc153fe2e6de28
record_format Article
spelling doaj-92ef2f18849140c690cc153fe2e6de282021-04-14T11:09:21ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382021-04-01251993200810.5194/hess-25-1993-2021Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling frameworkI. KramerY. BayerT. AdeyemoY. Mau<p>Declining soil-saturated hydraulic conductivity (<span class="inline-formula"><i>K</i><sub>s</sub></span>) as a result of saline and sodic irrigation water is a major cause of soil degradation. While it is understood that the mechanisms that lead to degradation can cause irreversible changes in <span class="inline-formula"><i>K</i><sub>s</sub></span>, existing models do not account for hysteresis between the degradation and rehabilitation processes. We develop the first model for the effect of saline and sodic water on <span class="inline-formula"><i>K</i><sub>s</sub></span> that explicitly includes hysteresis. As such, the idea that a soil's history of degradation and rehabilitation determines its future <span class="inline-formula"><i>K</i><sub>s</sub></span> lies at the center of this model. By means of a “weight” function, the model accounts for soil-specific differences, such as clay content. The weight function also determines the form of the hysteresis curves, which are not restricted to a single shape, as in some existing models for irreversible soil processes. The concept of the weight function is used to develop a reversibility index, which allows for the quantitative comparison of different soils and their susceptibility to irreversible degradation. We discuss the experimental setup required to find a soil's weight function and show how the weight function determines the degree to which <span class="inline-formula"><i>K</i><sub>s</sub></span> is reversible for a given soil. We demonstrate the feasibility of this procedure by presenting experimental results showcasing the presence of hysteresis in soil <span class="inline-formula"><i>K</i><sub>s</sub></span> and using these results to calculate a weight function. Past experiments and models on the decline of <span class="inline-formula"><i>K</i><sub>s</sub></span> due to salinity and sodicity focus on degradation alone, ignoring any characterization of the degree to which declines in <span class="inline-formula"><i>K</i><sub>s</sub></span> are reversible. Our model and experimental results emphasize the need to measure “reversal curves”, which are obtained from rehabilitation measurements following mild declines in <span class="inline-formula"><i>K</i><sub>s</sub></span>. The developed model has the potential to significantly improve our ability to assess the risk of soil degradation by allowing for the consideration of how the accumulation of small degradation events can cause significant land degradation.</p>https://hess.copernicus.org/articles/25/1993/2021/hess-25-1993-2021.pdf
collection DOAJ
language English
format Article
sources DOAJ
author I. Kramer
Y. Bayer
T. Adeyemo
Y. Mau
spellingShingle I. Kramer
Y. Bayer
T. Adeyemo
Y. Mau
Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
Hydrology and Earth System Sciences
author_facet I. Kramer
Y. Bayer
T. Adeyemo
Y. Mau
author_sort I. Kramer
title Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
title_short Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
title_full Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
title_fullStr Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
title_full_unstemmed Hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
title_sort hysteresis in soil hydraulic conductivity as driven by salinity and sodicity – a modeling framework
publisher Copernicus Publications
series Hydrology and Earth System Sciences
issn 1027-5606
1607-7938
publishDate 2021-04-01
description <p>Declining soil-saturated hydraulic conductivity (<span class="inline-formula"><i>K</i><sub>s</sub></span>) as a result of saline and sodic irrigation water is a major cause of soil degradation. While it is understood that the mechanisms that lead to degradation can cause irreversible changes in <span class="inline-formula"><i>K</i><sub>s</sub></span>, existing models do not account for hysteresis between the degradation and rehabilitation processes. We develop the first model for the effect of saline and sodic water on <span class="inline-formula"><i>K</i><sub>s</sub></span> that explicitly includes hysteresis. As such, the idea that a soil's history of degradation and rehabilitation determines its future <span class="inline-formula"><i>K</i><sub>s</sub></span> lies at the center of this model. By means of a “weight” function, the model accounts for soil-specific differences, such as clay content. The weight function also determines the form of the hysteresis curves, which are not restricted to a single shape, as in some existing models for irreversible soil processes. The concept of the weight function is used to develop a reversibility index, which allows for the quantitative comparison of different soils and their susceptibility to irreversible degradation. We discuss the experimental setup required to find a soil's weight function and show how the weight function determines the degree to which <span class="inline-formula"><i>K</i><sub>s</sub></span> is reversible for a given soil. We demonstrate the feasibility of this procedure by presenting experimental results showcasing the presence of hysteresis in soil <span class="inline-formula"><i>K</i><sub>s</sub></span> and using these results to calculate a weight function. Past experiments and models on the decline of <span class="inline-formula"><i>K</i><sub>s</sub></span> due to salinity and sodicity focus on degradation alone, ignoring any characterization of the degree to which declines in <span class="inline-formula"><i>K</i><sub>s</sub></span> are reversible. Our model and experimental results emphasize the need to measure “reversal curves”, which are obtained from rehabilitation measurements following mild declines in <span class="inline-formula"><i>K</i><sub>s</sub></span>. The developed model has the potential to significantly improve our ability to assess the risk of soil degradation by allowing for the consideration of how the accumulation of small degradation events can cause significant land degradation.</p>
url https://hess.copernicus.org/articles/25/1993/2021/hess-25-1993-2021.pdf
work_keys_str_mv AT ikramer hysteresisinsoilhydraulicconductivityasdrivenbysalinityandsodicityamodelingframework
AT ybayer hysteresisinsoilhydraulicconductivityasdrivenbysalinityandsodicityamodelingframework
AT tadeyemo hysteresisinsoilhydraulicconductivityasdrivenbysalinityandsodicityamodelingframework
AT ymau hysteresisinsoilhydraulicconductivityasdrivenbysalinityandsodicityamodelingframework
_version_ 1721527417097420800