Botswana’s Nationwide Tie Line Survey And New Magnetic Compilation

In 2010-2011, the Department of Geological Survey (DGS) acquired a new airborne magnetic Tie Line Survey over Botswana. It was flown on a 10 km by 50 km grid and totalled 70,176 line-km of data. The control lines were flown in single segments over a short time period to provide the most accurate levelled data set. Strategic deployment of magnetic base stations facilitated diurnal correction using a distance-weighting scheme. After compilation of the Tie Line Survey, some 70 higher resolution magnetic surveys were recompiled, most acquired by DGS supplemented by some from industry. They were then levelled to the magnetic datum provided by the Tie Line Survey, from which a new nationwide grid of total magnetic intensity at 50 m resolution was prepared. These data and enhanced nationwide magnetic grids were released by DGS in 2012.