Investigating Landsat data for continuous monitoring of ground electrical conductivity: implication for propagation at medium frequency in Ondo West

Abstract

Ground electrical conductivity (GEC) has many applications, which makes it worthy of continuous research. Apart from the configurations  of the radio transmitter and receiver, it is a major determinant of the electric field intensity of radio waves in the Medium Frequency (MF)  band. It is usually measured in such a way that both the researcher and the measuring instrument are in direct contact with the ground,  and measurements are made at some predetermined constant intervals to ensure good spatial coverage and even spatial distribution.  The direct method becomes cumbersome when the field of study is large because the GEC over the licensed coverage area must be  known such that electric field intensity can be predicted. At the planning stage, this ensures all parts of the licensed region are reached by  useful signals that can suppress interference at all times and seasons. The study is motivated by the possibility of using Landsat to  estimate GEC. This study utilizes Landsat images to first estimate the normalized difference salinity index and then, with the aid of map  algebra, generate another raster 2 whose pixels' values are the GEC. The study covers a landmass of 967 km in the Ondo West Local  Government Area (OWLGA). During analysis, the GEC was divided into five classes. The results reveal that the ranges of very low, low,  moderate, high, and very high GEC are 0.124 to 0.437, 0.438 to 0.937, 0.938 to 1.635, 1.636 to 2.524, and 2.525 to 3.600 mS/m, which have  mean values of 0.346 ± 0.109, 0.754 ± 0.103, 1.071 ± 0.089, 1.351 ± 2 0.067, and 1.564 ± 0.106 mS/m, and are dispersed over 176.45, 202.24,  214.14, 374.17, and 228.56 km , respectively. The values of GEC, their respective coverage, and spatial distribution recorded in this study  are strong enough to sustain the propagation of useful electric field intensity over the entire landmass of Ondo West Local Government if  a medium wave is established. The study recommends that the change in GEC with time in this field be studied.