Abstract

The project ‘research and training on irrigation with saline water in Tunisia’ (UNESCO, 1970) was set up to specify Tunisian standards for the use of saline water and to mitigate their effects on crop yields. The objective of this study is to assess the risk of long-term soil salinization by considering the agricultural practices mentioned in the project for the ‘water quality’ experiment in the semi-arid region Cherfech (Tunisia). Hydrus-1D model was used to simulate the movement of water and the transfer of salts. Soil hydraulic and solute transport parameters were estimated using inverse modeling. Calibration and validation of the model was made for the water and salt profiles carried out with four irrigation qualities QA, QB, QC and QD. Four scenarios over 50 years were studied: (i) S1 with rainfall (400 mm) only; (ii) S2 with rainfall and irrigations (1,400 mm); (iii) S3 with a 2 °C increase in temperature; (iv) S4 with the addition of 100 mm·d−1 of rainfall. The four scenarios highlighted the high risk of soil salinization, especially for the QB, QC and QD qualities after 20 years of irrigation and the deep dynamics of water and salts beyond the root zone which increases the risk of groundwater salinization.

HIGHLIGHTS

  • Saline water in Tunisia is a significant constraint to development.

  • CRUESI (1970) is the only local reference for the decision makers.

  • Inverse modeling is an essential tool to estimate soil transport parameters.

  • Assessing of soil salinization under different climate changes scenarios.

  • Use of saline water based on the project practices can lead to the destruction of agricultural soils after 20 years.

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Supplementary data