Fiji: Observations of erosion and sedimentation problems

As reported in an article on the internet, there was a major precipitation event in January 2012 which caused widespread flooding in western Viti Levu, Fiji’s largest island.  Six months later, while driving Queens Road between the towns of Nadi and Cuvu, I came across some of the resulting road damage shown in the following photos.  Storm water appears to have overwhelmed an inadequately-sized culvert sending flow from an intermittent stream over the highway.  I would guess that the powerful erosive force of water cascading over the lip of the fill caused headword erosion eating into the outer lane of this three-lane section of road.

Rather than making cosmetic repairs which will fail again when there is a comparable storm, maybe they need to construct a large box culvert or even a small bridge across the intermittent stream.

We’re in Fiji – no Corps of Engineers permit or storm water BMPs needed to construct a bridge across a small river on the Kings Road between the towns of Lautoka and Ba.  Note the lack of erosion and sediment controls in the following photos.  But, hey, it wasn’t all that long ago that we did it the same way in the USA!

Burning cropland in Fiji appears to a standard practice as I noticed smoke coming from distant fields in a number of locations along the west coast of Viti Levu.  I would strongly suspect that the practice contributes considerable sediment to local streams.