A forgotten treasure in the libraries: Neusiedler See / Fertő tó daily lake-level data from 30 October 1882 to 31 December 1909 – their climatological and hydrological relevance

This study presents hitherto neglected historical daily lake-level data of Neusiedler See from 30^th October 1882 to 31st December 1909 recorded in Fertőboz [German: Holling] and Neusiedl am See [Hungarian: Nezsider] at its southern and northern shores, respectively. The lake-level measurements were recorded in Hungarian hydrological periodicals and carried out by the Rábaszabályozó társulat (Rába Regulation Association) as part of plans to drain Neusiedler See. These data extend the modern measurements, which started on 17^th May 1930, by more than 28%. They offer important insights into the evolution and behavior of Neusiedler See, starting just 12 years after its famous desiccation (1865–1870), under different climatic and hydrological conditions. They thus provide an important historical data basis for refining our understanding of the present conditions as well as the future of Neusiedler See.