Transport and trapping of storm eroded fine sediment in fringing mangroves, Sawi Bay, Thailand

The field study site was the mangrove-fringed Sawi Bay in Thailand. At stations, a Seabird CTD equipped with an Analite nephelometer was used to obtain vertical profiles of temperature, salinity and optical backscatterance. Oceanographic moorings were deployed at sites T1-T4 and T6 during October 1998, April 1999 and November 1999. A mooring included an InterOcean model S4 current meter or a Woods Hole WHISL 2100 current meter, a Dataflow temperature-salinity recorder, and Analite nephelometers spread across the water column. A wave gage was also deployed at site T1, this was either an InterOcean model S4 current meter or a Rigo wave gage. Mooring T1 also comprised an Aanderaa model WLR5 tide gauge. All these units recorded 1-min averaged data at 10 min intervals. The nephelometers’ backscatterance data were converted to suspended matter concentration following the technique of Gibbs and Wolanski (1992) and Wolanski et al. (1995).

Transects of temperature, salinity and suspended sediment concentration were collected, both along-channel in the small tributaries draining into Sawi Bay and cross-shore in Sawi Bay, using a Seabird CTD equipped with an Analite nephelometer. A current meter, a tide gauge and 3 temperature and pressure recorders were attached to the Karmt 100 mooring for the first deployment. The tide gauge was replaced by a temperature and pressure recorder for the second deployment. Wind data were taken during field work using a hand held anemometer. The local bureau of meteorology office also provided long-term statistical data on winds for years prior to study.

Measurements in wave height, water depth, currents, salinity and suspended solids concentration were used to study typical circulation in Sawi Bay and the adjoining coastal waters of the Gulf of Thailand.