Integrated Analysis of River Channel Patterns in the Lower Yellow River Basin, China: From Inland Reaches to Estuarine Dynamics

This study aims to develop a quantitative classification method for river channel morphology in both runoff-sensitive and tide-sensitive reaches of the lower Yellow River Basin. Methodologically, we integrate hydraulic and sedimentological parameters based on flow resistance theory, employing the Darcy-Weisbach equation and Einstein’s hydraulic radius division method to derive morphological expressions for bedform and bankform. For the tide-sensitive reach, we incorporate the ratio of marine to fluvial transport capacity to capture the interplay of waves, tides, and river discharge. Classification criteria are established through parameter space fitting and validated using remote sensing imagery and field measurements from 1985 to 2021. Key results show that: 1) the runoff-sensitive reaches can be effectively classified into meandering, anabranching, and braided patterns with quantitative criteria; 2) our method identifies a previously unrecognized braided pattern in the Lijin-Qing 4 reach, challenging conventional assumptions about the tail reach morphology; 3) the tide-sensitive reach exhibits five distinct patterns—scattered, single-strand, divergent, realignment, and anabranching—with a general evolutionary cycle of ‘siltation-diffusion, extension-convergence, anabranch swinging, and channel realignment’; 4) analysis of 2012−2021 data reveals that reduced sediment concentrations drive a sustained anabranching pattern in the estuary. These findings contribute a transferable quantitative framework for channel classification and highlight the need for reach-specific adaptive management strategies in response to changing sediment dynamics.