Abstract

Effective channel forming discharges are those associated with largest bedload sediment yield over the long-term periods. Those are, therefore, discharges at which a flow produces most of a channel deformations. There can be up to 3 intervals of the effective channel–forming discharges observed on an individual river, differing in magnitude, frequency and relative position of the associated water levels to surfaces of various generations of channel bedforms and floodplain. The paper discusses approaches to the effective channel-forming discharge estimations, presents the experience of their mapping and considers natural and anthropogenic factors influencing their number, magnitude and frequency. It is shown that substantial changes of a river channel deformation regime caused by reservoir construction are caused by new conditions of the effective channel–forming discharges passage, which trigger a channel self-adjustment processes.

Keywords: channel-forming discharge, channel deformations regime, natural and anthropogenic controls, impact of reservoir construction