Georgi Bonchev’s paper “Contribution to the springs in Bulgaria”, 1939, and its significance for hydrogeology in Bulgaria

In 1939, one of the first summarizing works of the famous Bulgarian geologist Georgi Bonchev “Contribution to the springs in Bulgaria” related to groundwater in the country was published. In his field research, the author visited and described about 60 natural springs or groups of springs with temperatures from 20 °C to over 75 °C, attached to different tectonic zones, over 40 lukewarm and cold springs with mineralized waters and about 290 karst and other cold springs. This article is also relevant for modern hydrogeology. The presented general picture of the locations of the springs, the discharge and qualities of the waters from the natural springs before 1939 allows making comparisons of the occurred changes due to natural and anthropogenic factors.