[A-CG37] Water and Sediment Dynamics from Land to Oceans [En]

[ACG37-03] A reconnaissance study on estuarine suspended sediment dynamics in the Abukuma River, Japan

★Invited Papers

*Sheikh Hefzul Bari¹, Yoshiyuki Yokoo¹ (1.Graduate School of Symbiotic Systems Science and Technology, Fukushima University)

Keywords:suspended sediment, particle size, hysteresis, rating curve, sediment dynamics

Understanding suspended sediment dynamics is crucial for sustaining riverine and estuarine ecosystems. To gain insights into these dynamics, a reconnaissance study was conducted on the Abukuma River in Japan, focusing on its estuary region. Water samples were collected multiple times using a Niskin sampler. The laboratory analysis of samples included suspended sediment concentration, particle size distribution, and mineralogical composition. Ex-situ turbidity was measured using a multi-parameter water quality sonde. The mineralogical composition of the suspended sediment samples closely resembled the surface geology of the river, and ex-situ turbidity exhibited a strong correlation with suspended sediment concentration. Notably, the performance of the power-law rating curve relationship differed when sediment load, rather than concentration, was used. The feasibility of developing particle size rating curves appeared promising, though challenges remain in handling low sand concentrations during low flows as well as the quantity of available data. Analysis of a moderate storm event suggested that the contribution of uplands to the estuarine sediment load is relatively low during such events. Results indicate a potential 'storage-discharge' mechanism characterized by episodic sediment abundance, though further research is necessary to confirm this mechanism. Overall, the insights gained from this study provide a valuable foundation for designing long-term monitoring strategies.