Bedload and suspended sediment transport analysis in a Mediterranean intermittent river

Sediment transport processes in intermittent rivers and ephemeral streams remain poorly understood despite their growing ecological and geomorphological importance, particularly in Mediterranean environments where flow regimes are highly variable. This study quantifies and compares bedload and suspended sediment transport in the Sant Miquel River catchment (Mallorca, Spain), a representative Mediterranean intermittent river system. Field investigations were conducted from January 2023 to December 2024, combining passive integrated transponder tracers to monitor bedload with continuous turbidity-based measurements of suspended sediment. Four inter-survey periods were analysed to capture sediment transport dynamics under varying and representative hydrological conditions. The riverbed exhibits weak armouring ( D 50 /D 50ss = 0.70), indicating a mobile coarse surface sensitive to flood disturbance. Bedload mobility was size-selective: the smallest tracers travelled up to 540 m, whereas cobbles displaced on average 23 m, with 71% overall recovery. The first flood period accounted for 97% of the total estimated bedload volume (204 m 3 ), whereas subsequent periods showed limited transport (<3 m 3 each), reflecting event-driven pulses. Suspended sediment dynamics were similarly episodic: yields ranged from 0.2 to 26.8 t km −2 per event, resulting in an annual export of 26.9 t km −2 yr −1 , with >90% occurring during two short flood sequences. Hysteresis analysis revealed 62% clockwise and 38% counter-clockwise responses, demonstrating alternating sediment exhaustion and supply-driven phases. A strong positive correlation (R 2 = 0.79) emerged between mean bedload displacement and suspended sediment load. These findings advance understanding of sediment dynamics in intermittent rivers and ephemeral streams and highlight the importance of integrating bedload and suspended load assessments. The study contributes valuable field-based evidence for improving sediment transport models and supports geomorphic management strategies in Mediterranean catchments increasingly affected by climate variability. • Bedload and suspended load assessed in a Mediterranean intermittent river. • Tracked clast movements reveal variable bedload under episodic flows. • Suspended sediment peaks during floods and shows clear hysteresis. • Bed armouring measured and linked to sediment mobility patterns. • Results improve understanding of sediment dynamics under climate variability.