Brinkman, R., Wattayakorn, G., Wolanski, E., Spagnol, S., and Marshall, K. (2005) Storm-driven erosion of fine sediment and its subsequent transport and trapping in fringing mangroves, Sawi Bay, Thailand. Journal of Coastal Research, 42. pp. 211-220.

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Abstract

A field and model study was undertaken in 1998/1999 of the dynamics of water, fine sediment and particulate carbon in the degraded mangrove environment of Sawi Bay. Thailand. The currents were weak (:S 0.3 m s··\\) and principally diurnal tidal. The mean currents were primarily controlled by the prevailing circulation in the adjoining Gulf of Thailand and river runoff. There was very little biological detritus present to act as a coagulant for the fine cohesive sediment in suspension in the mangrove-fringed, muddy coastal waters. The sediment in suspension was mostly fine silt and clay aggregated into small flocs and resuspended by wind waves. This sediment was winnowed from the coastal zone and was advected back in this area by wind waves. The mangroves trap fine sediment and particulate carbon during such events. Riverine inflow of fine sediment in the mangroves was much smaller than the inflow of fine sediment from the sea. The mangroves at Sawi Bay grew on relatively shallow mud overlying a sandy substrate. They infilled with sediment and particulate carbon at a rate equal to, respectively, only 10% and 1% of that for the pristine mangrove environment of Hinchinbrook Channel, Australia. Further, mangroves were inundated only 10% as often at Sawi Bay than at Hinchinbrook, hence the export of nutrients from vegetation detritus was also smaller at Sawi Bay than at Hinchinbrook. Nutrient retention and recycling in mangroves were presumably higher at Sawi Bay than in Hinchinbrook Channel.

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