Reconstructing Spatial Denudation Patterns in a Reverse-Engineered Fluvial Catchment

Dnyanesh Borse , Arvind Singh, Gary Parker 

Quantifying the spatial heterogeneity of denudation rates is a challenge in geomorphology, particularly in tectonically subdued montane landscapes. We develop a sediment flux-based framework to estimate spatial denudation using a generic reverse-engineered fluvial catchment. The model combines physically based hydraulic geometry with a sediment transport relation to compute gravel flux throughout the channel network using bankfull discharge and grain size. Denudation rates are related to gravel flux and the associated contributing hillslope area through the assumption that denuded material contains a constant fraction of gravel depending on lithology and weathering. We found that the drainage network controls the spatial pattern, whereas climate and sediment/regolith properties control denudation magnitude, which decreases toward the catchment outlet. Sensitivity analyses evaluate the effects of basin scale, grain size, precipitation intensity, and gravel fraction on denudation variability. Our framework provides a computationally efficient approach for estimating spatial denudation in landscapes with sparse geochronological data.