The results of raising maximum, minimum, average annual air temperature in the basin of Desna river for the period from 1959 to 2011 years are shown. Increase of air temperature in the cold season and the increased frequency thaw leads to a decrease of the volume of spring flooding and maximum cost full-flowing drain. Annual rainfall in the basin of the Desna river for the period of 1971-2010 years is greater than it was before 1970. Mineralization of atmospheric precipitation has increased from 27.67 mg/dm3 in 1957-1960 to 40.85 mg/dm3 in 2008 – 2012 years by influence of toxic sodium ion, potassium, sulphates and ammonium or nitrate nitrogen. The chemical composition of atmospheric precipitation changed from calcium bicarbonate to calcium sulphate-sodium-magnesium. The average monthly cost of water during spring flooding in 1884-1940 . are higher than for the whole observation period in the last 40 years, but the costs in summer and winter low flow for the last 40 years had increased.
Keywords: thermal regime, atmospheric precipitation, annual sink, Desna.