![]() ![]() It determines how much sediment can accumulate on the marsh surface (Temmerman et al. Suspended sediment concentration: sufficient sediment in the system is essential for salt marshes to develop towards a long-term sustainable marsh. Older marshes will be able to withstand higher hydrodynamic conditions than younger pioneer marsh. But this will be very location specific, depending on direction of the currents, grain size of the initial substrate and age of the system. Indicative figures: a current velocity in the order of 1.2 m s -1 may be considered as an upper threshold for natural marsh development (Van Loon-Steensma et al. In contrast, the hydrodynamic energy needs to be sufficient to keep sediment suspended and to transport sediment to the upper part of the marsh. Sheltering from strong currents (cross-shore and longshore) and tidal waves is essential to prevent erosion and allow stabilization of the marsh platform by the vegetation. Sheltered hydrodynamic conditions: marsh development generally starts on a bare intertidal flat (mud flat) that is protected from high energy waves. ![]() ![]() The pioneer zone is flooded twice daily, the low marsh zone is inundated during mean spring tides (100-400 floods each year), and the middle/high marsh zone is flooded less than 100 times per year (Bakker et al. Within a salt marsh, various zones can be distinguished based on flooding frequency. Regular flooding is an essential aspect for marshes. They are located in the upper parts of the intertidal zone. Tidal environment: salt marshes are vegetated habitats bordering saline or brackish water bodies under tidal influence. ![]()
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