| Abstract: | This study provides an initial characterization of pollution associated with storm runoff in Tahiti. A thousand floodwater samples were collected from three representative catchments and subsequently analysed. The main pollution parameters chosen were total suspended sediment (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen (TN) and Total Phosphorus (TP). First, organic pollution appeared to be related closely to sediment, thus TSS could be used as a global indicator. Next, regression models between an event's TSS load and its hydrological characteristics were used to obtain annual load estimates. Great interannual variability was found to be strongly influenced by the few major floods that occur during the rainy season. Our results also emphasize the importance of the impact of urbanization on solid catchment exportation: from 60 TSS t/km2/year in a natural forested catchment, fluxes reached more than 700 TSS t/km2/year during preparatory urbanization earthworks before stabilizing at 140 TSS t/km2/year in a consolidated urbanized area. Clearly, runoff effects need to be taken into consideration for effective urban planning and for the preservation of the coastal environment in Tahiti. Copyright © 2002 John Wiley & Sons, Ltd. |
