Uptake of saline groundwater by plants: An analytical model for semi-arid and arid areas

• Published in: Plant and soil Vol. 175; no. 1; pp. 1 - 11
• Main Authors: Thorburn, Peter J., Walker, Glen R., Jolly, Ian D.
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01-08-1995; Springer
• Subjects: Agricultural soils; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Deficiencies. Phytotoxicity of elements. Salinity; Forest soils; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Groundwater; Plants; Plants and fungi; Soil depth; Soil salinity; Soil texture; Soil water; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Solutes; Water tables; Australia; Oceania; Forest soil; Solutes; Modeling; Eucalyptus; Transpiration; Semi arid zone; Dicotyledones; Angiospermae; Myrtaceae; Salinization; Hardwood forest tree; Water absorption; Simulation model; Mathematical model; Water resources; Briny water; Ground water; Hydraulic model; Arid environment; Prediction; Woody plant; Ecophysiology; Salinity; Water table; Water level; Forestry; Analytical method; Alluvial plain; Numerical simulation; Spermatophyta; Soil plant relation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/bf02413005

An analytical model, based on unsaturated zone water and solute balances, was developed to describe the uptake of saline groundwater by plants in dry regions. It was assumed that: i. initially, the profile had low water and salt contents to some depth; ii. both water and solutes move upwards from the water table by piston flow due only to plant water extraction; iii. the uptake of water concentrates solutes in the soil solution until some threshold salinity is reached, above which plants can no longer extract water due to osmotic effects; iv. uptake of the groundwater does not affect the water table level; and v. uptake of groundwater is only limited by transmission of groundwater through the soil. Model predictions were compared with measurements of groundwater uptake made over 15 months at five sites in a Eucalyptus forest in a semi-arid area, using independently measured model parameters. Depth and salinity of groundwater, and soil type varied greatly between sites. Predicted groundwater uptake rates were close to measured values, generally being within ~ 0.1 mm day⁻¹. Sensitivity analysis showed that groundwater depth and salinity were the main controls on uptake of groundwater, while soil properties appeared to have a lesser effect. The model showed that uptake of groundwater would result in complete salinisation of the soil profile within 4 to 30 yr at the sites studied, unless salts were leached from the soil by rainfall or flood waters. However, a relatively small amount of annual leaching may be sufficient to allow groundwater uptake to continue. Thus groundwaters, even when saline, may be important sources of water to plants in arid and semi-arid areas.