Abstract: This study describes methods of preliminary assessment of the state of meteorological and hydrological exploration of river catchments to develop common approaches to modeling and forecasting of hydrological processes. A brief overview is given of the organization of monitoring systems in different countries. The quantitative assessment is performed of the ground observation coverage over the largest river basins within the European territory of Russia with cartographic visualization in GIS. Recommendations are given on the use of specific hydro-geological models for forecasting for catchments assigned to a particular group according to the state of exploration of runoff formation process.