<![CDATA[Suspended-sediment transport in small tropical rivers can change sharply over short distances because discharge, sediment availability, and cross-sectional mixing vary simultaneously. This study examined longitudinal changes in water discharge, suspended-sediment concentration (SSC), and instantaneous suspended-sediment flux along the Mangottong River, South Sulawesi, Indonesia. Five observations were available at each upstream, midstream, and downstream cross-section. Point discharges were verified from the field calculations, SSC was derived from laboratory dry-mass measurements, and section concentration was evaluated using discharge weighting. Suspended load was calculated as 0.0864CQ, with C in mg L⁻¹ and Q in m³ s⁻¹. Section discharge increased from 5.178 to 7.554 and 8.438 m³ s⁻¹, whereas discharge-weighted SSC changed from 626.5 to 568.3 and 1,829.2 mg L⁻¹. Corresponding suspended loads were 280.3, 370.9, and 1,333.5 t d⁻¹. The downstream section therefore carried 4.76 times the upstream load while water discharge increased only 1.63-fold. The lower-reach amplification was driven primarily by sediment enrichment rather than discharge growth alone, demonstrating the value of discharge-weighted sampling for interpreting sparse river surveys.]]>
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