Modeling Saline Soil Remediation Using the Surface Evaporation Capacitor Approach.

Soil salinization is a pervasive problem in arid environments, frequently exacerbated by anthropogenic activities. Remediation commonly involves soil leaching through natural precipitation or controlled, human-made flooding events. Accurate prediction of solute transport during these leaching processes is complex, as it is controlled by soil physical and hydraulic properties, climatic conditions, evaporation rates, and the volume and timing of infiltration. Precise physically-based numerical models are necessary for exact descriptions but demand detailed input regarding soil and environmental parameters.

This study examines a simplified, physically-based alternative: the Surface Evaporation Capacitor (SEC) concept proposed by Or and Lehmann in 2019. Originally developed to predict soil porewater evaporation, the SEC model posits that porewater shallower than the soil capillary length is consumed by surface evaporation, while deeper porewater remains protected from this process.

We adopt the SEC concept to estimate solute dynamics within the vadose zone and predict long-term salt accumulation profiles. By integrating soil capillary length, ambient evaporation, and the depth of natural or artificial wetting, the SEC allows for a simple determination of salt fate, specifically estimating the leaching depth required to prevent salinization in the root zone and near the surface.

We validated the SEC approach by comparing its predictions against detailed field measurements collected in a super-arid region of Israel, alongside results from a detailed physically-based numerical model. Results confirm the Evaporation Capacitor Model's validity as an accurate proxy for estimating annual solute dynamics and salt accumulation in saline soils. While the complex numerical model provides exact temporal descriptions, the simplified SEC model offers an accurate  and easily implementable net estimation of salt transport, making it highly valuable for large-scale practical remediation assessment and management.