Creeks are essential for salt marshes by conveying water and sediment through this geomorphic system. In this paper, we investigate the mechanisms that determine the residual sediment flux using measurements conducted in tidal creeks in salt marshes of the Yangtze Estuary. A main creek and a secondary creek were studied to explore whether the mechanisms determining residual sediment fluxes through the main creek differ from those in the secondary creek. Measurements in creeks were carried out over 5 years, spanning different months. Sediment import was found during most tides, both in the main creek and the secondary creek, implying that creeks in Chongming generally function as a conveyor belt of sediment into the marsh. However, sediment export can occur during certain overbank tides. When comparing the role of creeks in drainage and sediment delivery, the main creek functions more in delivering sediment while the secondary creek primarily serves as a drainage conduit. To better understand the mechanisms behind sediment fluxes, the residual sediment flux was compared with the residual discharge and the sediment differential (differences in sediment concentration between flood and ebb). Overbank tides generally lead to a net outward discharge as more water from saltmarshes can be concentrated into the marsh creek during ebb tides. This net outward discharge tends to export more sediment during ebb tides. However, due to the sediment abundance during the flood phase in the turbid environment, sediment import can be expected even with the residual export of water. Export of sediment was only found for the few tides with a net outward discharge and a small positive sediment concentration differential. Large negative sediment differentials (larger averaged suspended sediment concentration during ebb tides) have not been observed because the sediment supply during ebb is limited. This paper unravels how the sediment differential and residual discharge contribute to the residual sediment flux, providing a better understanding of sediment dynamics in marsh creek systems.

@en

In this contribution, We analyze the bandwidth versus accuracy trade-offs of conventional two-step de-embedding approaches, often employed to extract the device model parameters. The accuracy limitation of incorporating the pad/line section of classical DUT test-fixtures into shunt-series complex and frequency-dependent elements is analyzed by means of linear circuit simulations and EM parametric analysis. The de-embedding accuracy is then evaluated by employing 3D surfaces to include both the frequency and the geometrical dependency. To validate the presented analysis, classical device monitoring parameters are extracted versus frequency for the same nMOS device embedded in two different fixtures. One topology only supports pad level calibration, thus including the fixture pad/line section in the de-embedding process. The second topology allows a direct on-Wafer calibration (reference plane set on metal-1 in close proximity to the DUT) thus minimizing the residual parasitics to be removed by the de-embedding step. Experimental data are then presented and compared to simulation test benches to highlight the improved consistency of the extracted model parameters of the metal-1 calibration approach up to 220GHz.@en