A dynamical system approach to soil salinity and sodicity. (September 2015)

• Record Type: Journal Article
• Authors: Mau, Yair; Porporato, Amilcare
• Is Part Of: Advances in water resources. Volume 83(2015)
• Page Start: 68
• Page End: 76
• Publication Date: 2015-09
• Subjects: Salinity -- Sodicity -- Irrigation -- Exchange reactions; Hydrology -- Periodicals; Hydrodynamics -- Periodicals; Hydraulic engineering -- Periodicals; 551.48
• DOI: 10.1016/j.advwatres.2015.05.010
• Languages: English
• ISSNs: 0309-1708

Abstract

Highlights: We model the effects of irrigation on soil salinity and sodicity in the root zone. The time scales of salinization and sodification were quantified. Salinity influences sodification, but is unaffected by sodium levels in the soil. We determine the conditions in which irrigation increases salinity/sodicity hazard. Abstract: Soil salinity and sodicity impose severe constrains to agriculture, especially in arid and semi-arid regions, where good-quality water for irrigation is scarce. While detailed models have been proposed in the past to describe the dynamics of salt and sodium in the soil, they typically require cumbersome calculations and are not amenable to theoretical analysis. Here we present an analytical model for the dynamics of salinity and sodicity in the root zone. We determine the dependence of steady-state salinity and sodicity levels on irrigation water quality and derive the trajectories in the phase space. The only stationary solution the equations admit is a stable node. Through numerical integration and analysis of the eigenvalues of the derived two-dimensional system of equations, the slower time scale associated with sodification is quantified with respect to the faster time scale associated to salinization. The role of different cation exchange equations (Gapon and Vanselow conventions) are shown to be practically the same with regard to the phase-space dynamics and the time scales. The results can be applied in controlling for low levels of salinity and sodicity, and in planning remediation strategies that are timely and economical.