| Summary: | The present study aims to investigate the evolution of river networks and floodplain geomorphological features of river Raidak within the dynamic Himalayan foreland basin regime over 65 year's timescale (1955–2020). High resolution satellite images and old maps have been used to prepare the floodplain geomorphological maps. Additionally, field verification technique has been adopted to improve the accuracy of floodplain landforms mapping. Sedimentary log analysis was conducted in order to identify the floodplain types and fluvial architectural elements in the floodplain. The nature of channel oscillation has been assessed using different parameters (channel length, channel width, sinuosity, bank line migration and erosion-accretion area). Results showed that progressive migration of meander bends and channel shifting on a recent past time-scale have resulted into many floodplain geomorphic features such as cut-offs, palaeochannel, backswamps, abandoned channel and meander scroll bar on Holocene floodplain surface. These floodplain landforms are more prominent on the middle and lower part of the floodplain. Numerical investigation showed variation in channel sinuosity of the middle and lower reach of river Raidak-I (1.85, 1.64 and 1.73 during the year 1955, 1987 and 2020 respectively) suggesting channel lengthening and shortening during different time period through mender development and cut-offs formation. Result also shows spatiotemporal variation in channel width and increasing trend of erosion-accretion area during the period 1987–2020. The sedimentary log analysis suggests non-cohesive medium energy (specific stream power varies between 10 and 300 Wm-2) floodplain of principal class B characterized with meandering and braided channel pattern, multiple sequence of Holocene sediments and existence of different floodplain landforms. Different natural processes (variable discharge, frequent floods, active tectonics, meander migration and channel shifting) and human interferences (channelization, mining activities, construction of cross-sectional structures and land use changes) have been responsible for evolution and morphological modification of Raidak river system and their floodplains.
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