Influence of network geometry on long-term morphodynamics of alluvial rivers

作者：Fergus McNab, Taylor Schildgen, Jens M. Turowski, Andrew D. Wickert · 发表于：Earth Surface Dynamics · 年份：2025 · DOI：10.5194/esurf-13-1059-2025 · 被引用次数：1 · 研究领域：Geological formations and processes、Hydrology and Sediment Transport Processes、Geology and Paleoclimatology Research

Abstract. Alluvial rivers respond to external forcings such as variations in sediment supply, water supply and base level by aggrading, incising and adjusting the rates at which they transport sediment. These processes are recorded by landforms, such as terraces and fans, that develop along river courses, and by stratigraphy in downstream sedimentary basins. Many concepts we use to interpret such records are derived from models that treat alluvial rivers as single-segment streams: for example, the length of an alluvial river has been shown to set its response time to external forcing. However, alluvial rivers in nature exist within interconnected networks, complicating the application of such concepts to real systems. We therefore adapted a model describing long-profile evolution and sediment transport by transport-limited, gravel-bed alluvial rivers to account for network structure, and explored the response of large numbers of synthetic networks to sinusoidally varying sediment and water supply. We show that, in some respects, networks behave similarly to single-segment models. In particular, single-segment models predict well properties that integrate across the entire network, such as the total sediment output. We use this behaviour to define an empirical network response time, and show that this response time scales with network mean length, or the mean distance from all a network's inlets to its outlet. Nevertheless, interactions between segments do lead to complex sign...