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Kanzari S.,National Institute for Research in Rural Engineering | Kanzari S.,National Engineering School of Tunis | Hachicha M.,National Institute for Research in Rural Engineering | Bouhlila R.,National Engineering School of Tunis | Battle-Sales J.,University of Valencia
Soil and Water Research | Year: 2012

Arid and semi-arid regions face the risk of soils and aquifers salinization. Rainy events are rare which is characteristic of these regions. They play a significant role in the leaching of salts from topsoil to deeper layers, which increases the risk of aquifers salinization. For this reason, a plot was selected in the semi-arid region of Bou Hajla (Central Tunisia). The simulation of water and salts dynamics was carried out by Hydrus-1D. Model calibration was realised on a flood irrigation experiment during 10 days and in a depth of 4 m. The hydrodynamic parameters were determined by inverse modelling. Model validation was performed successfully during 577 days. The simulation of water and salts dynamics has allowed the analysis of two scenarios: (i) the effect of a very rainy event (> 50mm/day) on the dynamics of salts. This type of event allows leaching of the accumulated salts in the topsoil which promotes their burial in the depth; (ii) the long-term evolution of the saline profile in 20 years showed the cyclical nature of salts leaching in the topsoil, the permanent accumulation of salts in the depth of around 2 m, and a continuous leaching in the deeper layers (around 4 m), which may increase groundwater contamination risk.

Bouksila F.,National Institute for Research in Rural Engineering | Persson M.,Lund University | Bahri A.,African Water Facility | Berndtsson R.,Lund University
Hydrological Sciences Journal | Year: 2012

Electromagnetic induction measurements (EM) were taken in a saline gypsiferous soil of the Saharan-climate Fatnassa oasis (Tunisia) to predict the electrical conductivity of saturated soil extract (ECe) and shallow groundwater properties (depth, Dgw, and electrical conductivity, ECgw) using various models. The soil profile was sampled at 0.2 m depth intervals to 1.2 m for physical and chemical analysis. The best input to predict the log-transformed soil salinity (lnECe) in surface (0-0.2 m) soil was the EMh/EMv ratio. For the 0-0.6 m soil depth interval, the performance of multiple linear regression (MLR) models to predict lnECe was weaker using data collected over various seasons and years (Ra 2 = 0.66 and MSE = 0.083 dS m-1) as compared to those collected during the same period (Ra 2 = 0.97, MSE = 0.007 dS m-1). For similar seasonal conditions, for the Dgw-EMv relationship, R2 was 0.88 and the MSE was 0.02 m for Dgw prediction. For a validation subset, the R2 was 0.85 and the MSE was 0.03 m. Soil salinity was predicted more accurately when groundwater properties were used instead of soil moisture with EM variables as input in the MLR.Editor D. Koutsoyiannis; Associate editor K. HealCitation Bouksila, F., Persson, M., Bahri, A., and Berndtsson, R., 2012. Electromagnetic induction predictions of soil salinity and groundwater properties in a Tunisian Saharan oasis. Hydrological Sciences Journal, 57 (7), 1473-1486. © 2012 Copyright 2012 IAHS Press.

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