The main objective of this study consists in systemization, estimation and correction of model parameters and on this basis in investigation and modeling of runoff formation processes for poorly explored basins within the deterministic modeling system with distributed parameters "Hydrograph" . Ten watersheds within r. Lena basin have been chosen as objects of investigation. Based upon comparison of calculated and observed runoff hydrographs, a conclusion was drawn on good possibilities of "Hydrograph" model use for studying the processes of runoff formation on East Siberia regions.