Sedimentary deposits contain a record of long-term sediment flux and sediment yield rates for geological systems. Furthermore, studies that quantify detailed analysis of closed systems are particularly useful for validating the efficacy of other tools to derive sediment discharge, sediment flux, and sediment yield for use in forward stratigraphic modeling. We test the reliability of the BQART equation using millennia-scale sediment-flux estimates derived from five fluvial–bay systems of western Louisiana and Texas. The BQART equation (derived from measurements of modern fluvial load) provides a relatively robust tool to derive sediment yield or sediment flux for small, low-relief coastal-plain fluvial systems.

The fluvial–bay systems studied span humid (Calcasieu, Louisiana) to semiarid (Nueces, Texas) climate zones, and provide a natural laboratory to study effects of Holocene climate change on sediment flux. These systems preserve a Holocene record of variable sediment yield that can be linked to climate-induced vegetation effects. High sediment yield of the Calcasieu fluvial system during the mid-Holocene is attributed to climatic, vegetation-cover shift to semiarid grassland, respectively. Low sediment yield of the Nueces fluvial system during the mid-Holocene is attributed to a climatic, vegetation-cover shift to arid desert, respectively. This study supports theoretical arguments that sediment yield is greatest in semiarid to subhumid fluvial systems with diminishing sediment yield in arid or humid climatic regimes.

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