Assessment of structural sediment connectivity using different weighting factors and field data in a mountain–piedmont catchment of the Pampean Ranges of Argentina

Abstract

Sediment connectivity studies provide a holistic approach to assessing sediment fluxes in catchments, as they consider the spatial configuration of landscape components and their functional interrelationships. The index of connectivity (IC) is one of the most widely used methods to evaluate structural sediment connectivity. The IC has been adapted to different landscape contexts through various formulations of the weighting factor (W), reflecting the flexibility of the method. However, we understand that more than developing new variants, it is necessary to critically evaluate existing formulations to contribute to the standardization of the IC. This study evaluates structural sediment connectivity in the Alpa Corral-Seco catchment (Córdoba-Argentina), a mountain–piedmont system with variable vegetation cover. The aim is to compare different formulations of the W factor based on Manning's roughness coefficient (i.e., ICp, ICm and ICz) and to identify the most suitable IC for this environment. The analysis was complemented by satellite image processing and field observations to enhance the interpretation of connectivity patterns. Results indicate that ICz provides the most reliable representation, showing the highest capacity to discriminate spatial variability across different environmental contexts and the strongest agreement with field observations. ICm preserves the main geomorphological contrasts but attenuates spatial variability, making it suitable for coarse scales analyses, whereas ICp tends to smooth connectivity patterns and overestimate connectivity in vegetated areas. Spatial analysis reveals high connectivity in the mountainous sector, where the weathering and erosion of granitic outcrops and sparse vegetation favour the sediments production and transfer. Conversely, the piedmont shows low connectivity, with processes concentrated along the main channel. These findings highlight the importance of field validation and the effectiveness of Manning-based W factors in geomorphological heterogeneous catchments when using medium-resolution DEMs.