The justification of the geographical river-bed study as substantive research field is founded. The structure of this study is under consideration. Special attention is paid to its component - river-bed morphodynamics that deals with river-bed morphology, river-bed deformation and water regime, technogenic changes of river-bed processes and forms, hydromor-phological interrelations between river-bed forms parameters and factors of river-bed processes. The connections of riverbed morphodynamics with flood-plane study, longitudinal profile theory, and studies of factors and conditions of river bed processes.