Estimating unsaturated soil hydraulic properties to predict water dynamics through a vertical soil profile under the effects of irrigation, drainage and evapotranspiration is imperative for managing soils in the arid regions. The aim of this work was to determine the soil water retention curve and the hydraulic permeability function of a bare soil profile in a Tunisian oasis threatened by salinization. The developed model combines a numerical inversion of the unsaturated flow equation with the BOBYQA optimisation algorithm. The direct model solved the Richards equation using a cell-centred finite difference model. Hydraulic properties were described by van Genuchten-Mualem models. Input data for the inverse problem are the infiltration flow, soil water contents and pressure heads measured during ponded infiltration and internal drainage tests. Numerical simulations of these two tests were performed considering a homogeneous single-layer soil profile but a better fitting between measured and simulated water contents was obtained when the soil profile was divided into five sub-layers. The hysteresis phenomenon was highlighted from the soil water retention and the relative permeability curves corresponding to the ponded infiltration and internal drainage tests.
The groundwater aquifer in the coastal region of the northwest of Oman has been used extensively since the early 1980s for agricultural, industrial and municipal purposes. The over pumping of this reservoir has led to the intrusion of seawater and therefore to the deterioration of the groundwater quality. In this study, an investigation was carried out in the southern part of this region to identify the quality of groundwater, to understand the main sources of groundwater mineralisation, and to check the suitability of groundwater for drinking and irrigation. The spatial distributions and temporal variations of groundwater level and electrical conductivity were studied for the period from 1982 to 2005 using data collected from 225 wells. In addition, groundwater samples were collected recently in 2012 from eight wells and analysed for pH, EC, and major ions to understand the sources of dissolved ions and assess the chemical quality of the groundwater. The study area was divided into two strips parallel to the coastline, A and B, located in the discharge and recharge parts of the aquifer, respectively. Results showed a significant increase in the degree of water mineralisation in the direction of south to north following the regional flow direction. Results showed also that the groundwater in the last area could be used for irrigation with little danger of exchangeable sodium while this aquifer is unsuitable for irrigation in the discharge area because it presents a very high salinity hazard.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.