<em>Land use and erosion risk in small forest catchments on the Coral Coast of Fiji: baseline estimates of sediment inputs to coastal lagoons.</em> — ASN Events

Land use and erosion risk in small forest catchments on the Coral Coast of Fiji: baseline estimates of sediment inputs to coastal lagoons. (11611)

Arishma R. Ram 1 , James P. Terry 2
  1. School of Geography, Earth Science & Environment, University of the South Pacific, Suva, Fiji
  2. Department of Geography, National University of Singapore, Kent Ridge, Singapore

Information on soil erosion rates and suspended sediment transport in river catchments is scarce in tropical Pacific Island nations. Nonetheless, island coastal ecosystems are threatened by land-based activities that cause erosion and sediment delivery by fluvial processes. In Fiji, coastal hinterlands are often characterized by small steep watersheds which have a low retention capacity for eroded sediments. Adjacent coral reefs and lagoons may therefore suffer degradation when exposed to periodic inputs of high sediment loads. That being said, however, very little empirical evidence exists to quantify the linkage. The ‘Coral Coast’ of southern Viti Levu is Fiji’s longest continuous fringing reef, but faces threats from land use change in coastal catchments. Yet, the identification of vulnerable areas and implementation of watershed restoration efforts is hindered by a lack of sufficient data on erosion risk and suspended sediment transport.

To address such issues, the present study investigates the Votua Creek catchment – a steep naturally forested watershed on the Coral Coast. The aim is to provide baseline data against which comparisons can be made for neighboring catchments where land management is more intense. Combined use of the Universal Soil Loss Equation (USLE) and GIS techniques enabled the identification of potential areas of soil erosion risk. Temporal sediment dynamics were also examined in relation to catchment rainfall parameters by continuous monitoring of stream water turbidity in the Votua Creek over 8 months from October 2009 to June 2010. The presentation will discuss the major findings of the study and implications for environmental protection of the Coral Coast area.

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