Sediment deposition rate in the Falefa River basin, Upolu Island, Samoa.
The (137)Cs method was employed to investigate the recent historical rate of sediment deposition on a lowland alluvial floodplain in the Falefa River basin, Upolu Island, Samoa. Caesium stratigraphy in the floodplain sediment profile was clearly defined, with a broad peak at 145-175 cm depth. The measured rate of vertical accretion over the last 40 years is 4.0+/-0.4 cm per year. This rate exceeds observations in humid environments elsewhere, but is similar to that recorded on other tropical Pacific Islands. Available flow data for the Vaisigano River in Samoa give a 'near-catastrophic' index value of 0.6 for flood variability. This is associated with the occurrence of tropical cyclones and storms in the Samoa area. Large floods therefore probably contribute to the high rate of floodplain sedimentation on Upolu Island. A small but growing body of evidence suggests that fluvial sedimentation rates on tropical Pacific islands are some of the highest in the world.
Terry
James P
JP
Department of Geography, University of the South Pacific, Private Mail Bag, Suva, Fiji Islands. terry_j@usp.ac.fj
Kostaschuk
Ray A
RA
Garimella
Sitaram
S
D002588:Cesium Radioisotopes / Q000032:analysis*; D005843:Geography; D019015:Geologic Sediments; D009689:Nuclear Warfare; D011847:Radioactive Fallout; D011848:Radioactive Pollutants / Q000032:analysis*; D045483:Rivers; D018947:Samoa; D014329:Tropical Climate
D002588:Cesium Radioisotopes; D011847:Radioactive Fallout; D011848:Radioactive Pollutants