Evaluation of drainage systems performance using digital soil salinity mapping

A Latin hypercube sampling approach was employed to evaluate the drainage system performance in rehabilitated and modernized lands in Tanour-Lahour, Yazd Province. This determined the locations for collecting 147 soil samples, 28 water samples, and 225 electromagnetic conductivity readings. Soil and water salinity and ionic composition used to interpolate and create root zone soil salinity variation maps. The regression results showed that in both cases, only the ‎device‎ measurement in the horizontal position has a significant relationship with the average root zone ‎soil ‎salinity. Accordingly, the assessment of soil salinity based only on traditional sampling and ‎laboratory ‎analysis cannot provide a proper view of the salinity and also an overview of the ‎performance of the ‎drainage system. The land’s soil salinity estimation using ‎apparent electrical ‎conductivity data showed a better relationship between the plant health status and the ‎performance of the land’s drainage system.‎ Accordingly, the soil salinity in the middle lands has been completely controlled in such a way that the ‎ECe has even reached less than the irrigation water EC, while in the ‎marginal lands equipped by ‎the drainage system and where the drainage occurred only by the main drainage ditch, the ‎soil salinity values ‎were higher than middle lands.‎ ‎The time sequence of drainage salinity indicates that ‎the ‎drainage water salinity was almost constant in time. The drainage salinity in the collectors remained constant about 20dS/m and in the main drain ditch about 33 dS/m. ‎These conditions ‎indicate that the drainage system has approached steady or quasi-steady conditions. ‎