The stretch of river between upstream Tete Province and Cahora Bassa Gorge had not been quiet lately either. East African hydrographic vessels often cruised this section, surveying and marking the channel.
For the Zambezi River below Tete City, silt accumulation was the chief obstacle hindering the development of navigation. For this stretch, however, the greatest natural obstruction was the reefs in the river.
The team led by Koboda, an East African geological expert, was using sonar on the Zambezi River to reexamine the geological conditions of this section.
"As early as the nineteenth century, two scientists from France and Sweden had begun measuring the speed at which sound waves traveled through water. In ancient times, people had already discovered that sound could travel underwater."
"For instance, Da Vinci recorded related experiments at the end of the fifteenth century. By inserting a tube beneath the water, one could hear the sounds of distant vessels. Even earlier, the Far East Empire had similar records in the pre-Qin Warring States period text Mozi."
"However, the rapid development of sonar equipment around the world had to wait until after the twentieth century began, especially as nations sought to counter submarines, this new kind of underwater combat vessel. This drove the swift advancement of sonar equipment in other countries during World War I, particularly Britain and France."
"Our East African research into sonar began in the 1890s of the last century, so we were considered among the world's leaders. In 1897, the first sonar was invented, though it could only passively receive sound waves at the time. It had originally been developed to deal with submarines as well."
"Besides the Empire, Britain also began researching sonar equipment relatively early. Yet it was not until the beginning of this century that Britain's Lewis invented the hydrophone.