Mapping Soil Salinity in Arid Lands Using Electrode Sensors, Geographic Information Systems (GIS) and Global Positioning Systems (GPS) Techniques

Nassim Al-Abed¹, Fayez Abdulla², Hani Abu-Qudais², Ziad Ghazawi²

¹ Center for Environment and Water, Research Institute
King Fahd University of Petroleum and Minerals. Dhahran, Saudi Arabia
e-mail: nassim@kfupm.edu.sa

² Department of Civil Engineering, College of Engineering, Jordan University of Science and Technology, Irbid, Jordan
 

Abstract

Jordan is categorized as an arid to semi arid country, with characteristics of irregular rainfall, high temperatures and evaporation rate. The soil in the southern part of the Jordan valley is saline due to natural causes. Addressing the soil salinity problem spatially using the traditional method of soil sampling and lab analysis is a tedious task, expensive and time consuming. The use of GIS and GPS in combination with electrode sensors technique can be of great help, in defining the saline areas fast and economically when compared to the traditional method.
This study was carried out on different farm units in development unit 51 which is located in the southern part of the Jordan Valley, Jordan. Soil EC responds to the amount of salt in the soil as well as indicates the soil’s composition such as the amount of sand, clay, organic matter, and water content. In this study we used the Veris 3100 which is a soil EC Mapping System that acquires continuously-sensed soil electrical conductivity data from two soil depths (0-30 cm and 30-90 cm). The EC measured in this study is called the electrical conductivity of the bulk soil (ECa) or the apparent electrical conductivity. We studied the consistency of this new technique by measuring ECa in the field with length and width. The actual data measured for the shallow depth (0-30 cm) with length has a minimum and maximum of 12.1 and 390.6 and mean of 68.84. For the width measurements the minimum and maximum were 16.2 and 380.1 and mean of 77.61. We also studied the effect of rainfall on the soil salinity, where the effect of rainfall on the salinity measurement was very clear. The average salinity value (ECa) measured in February (winter season) for farm unit 411 was 44.92 and the maximum and minimum values were 0.8 and 255.7. This was for the shallow depth (0-30 cm) layer. Comparing this value to the September (summer season) ECa value of the same area, the average was 77.49 and the minimum and maximum were 16.2 and 380.1 respectively. In this study we used ESAP version 2.3. ESAP is a statistical software package for estimating field scale spatial salinity patterns from electromagnetic induction signal data. This study showed that this technique is feasible at a field scale in Jordan for defining the saline soils in a spatial, accurate and detailed way that was difficult in the past using the traditional approach. Eventually, this approach will prove to be very valuable when it comes to mapping arid regions soil salinity for an eventual reclamation.