At the present time, the increased occurrence of drought and water scarcity (that is the availability of domestically and commercially usable water) is one of the most significant problems of the 21st century. Water is primary means between potential climate changes and the future development of natural subsystems and socioeconomic sectors. In the present time the climate change issue resonates not only among scientists in present time, but also among politicians, in which hands are the possibilities to take appropriate measures to eliminate climate change impacts. In this paper are shown some aspects of the flow regime of the Slovak rivers, derived from the results of continuous monitoring of hydrological processes. Continuous monitoring of the quantity of surface water is the basis for the assessment of the current status of surface water, for assessment of its future development and to estimate negative effects of climate change. This knowledge is necessary to create measures to minimize the consequences of extreme phases of the hydrological regime (floods and droughts) and the consequences of climate change impacts as well. In Slovakia the monitoring of the quantity of water flows is performed by the Slovak Hydrometeorological Institute in the State hydrological network. The outputs of this monitoring represent important input for the state water planning and water policy.