Conditions to Preserve the Sedimentary Record of Channel Planforms in Temperate Rivers of the Northern Hemisphere

We aim to identify conditions that influence the preservation of a complete record of channel planforms in the topmost layer of floodplains, prior to the maintenance in the rock record. We have tested a hypothesis that a successive decrease of stream power and channel belt width are necessary to preserve the record of channel planforms in the topmost floodplain layer over 10−3to 10−4‐year time scales. A literature review was conducted for rivers of the temperate zone of the Northern Hemisphere. Stream power, valley, and channel belt widths, paleodischarges, sediment grain‐size, and age of paleochannels were used to identify four groups of rivers with preservation potential ranging from tens of thousands years to annual time scales. The decrease in stream power followed by sustained low stream power, and successive decrease of channel belt width were identified in rivers preserving a 10−3to 10−4‐year record of channel planforms. River valleys with the record of at least two generations of paleochannels, and valley width/channel belt width ratios between 6 and 12, potentially preserve fluvial records over 10−3to 10−4‐year time scales. We analyzed unusually well‐preserved records of channel planforms from the Obra and Sió Rivers (central Europe). A determination of trends in changes of stream power and channel belt widths based on an extensive set of geophysical, geological data, and sediment dating from earlier studies, confirmed the tested hypothesis. The proposed framework can be extended by fluvial records preserved by large, and coastal rivers, with the potential to include ancient fluvial records. Sediments deposited by rivers are archives preserving memory of past events, such as floods or changes in the type of channel (e.g., from braided to meandering). The memory of some rivers reaches back to thousands of years whereas others contain the record of channel changes from the last few years. We aim to define what conditions influence these differences. We analyzed changes in past discharges, flow energy, and widths and age of channel belts preserved in valley floors, in rivers situated in the temperate zone of the Northern Hemisphere. We found that a decrease in flow energy followed by sustained low energy of the flow, and successive decrease of channel belt width, favor the preservation of past fluvial events over 10−3to 10−4‐year time scales. Rivers containing annual records are shaped by high flow energy, often eroding the record of past events. We analyzed unusually well‐preserved sedimentary records from the middle Obra and Sió Rivers (central Europe). They contain traces of former river channels from the last 13,000 and 18,000 years, respectively. In both cases, the flow energy and channel belt width decreased in particular generations of former channels, and this confirms the findings from the other analyzed rivers. We aim to identify conditions influencing the preservation of complete record of channel planforms in the topmost layer of floodplainsA successive decrease of stream power and channel belt width favor the preservation of channel planforms over 10−3to 10−4‐year time scalesRiver valleys with valley width/channel belt width ratios from 6 to 12, potentially contain fluvial record over 10−3to 10−4ky time scales We aim to identify conditions influencing the preservation of complete record of channel planforms in the topmost layer of floodplains A successive decrease of stream power and channel belt width favor the preservation of channel planforms over 10−3to 10−4‐year time scales River valleys with valley width/channel belt width ratios from 6 to 12, potentially contain fluvial record over 10−3to 10−4ky time scales