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Nephelometric turbidity is an optical index for the side scattering of light caused by fine particles suspended in water. When a mixed composition of suspended inorganic and organic materials, including dissolved organic material, is present, turbidity measurements can be affected by the different optical properties of the organic and inorganic materials present, and different turbidimeters are more or less sensitive to these influences. Two different methods of nephelometric turbidity measurement were assessed (using instruments confirming to two different turbidity standard methods: EPA 180.1 and ISO 7027). We investigated the influence of particulate organic matter and coloured dissolved organic matter on relationships between turbidity and suspended sediment concentration for rivers in diverse Otago catchments, in the South Island of New Zealand. The presence of organic matter and dissolved colour affected turbidity measurement owing to light absorption; however, turbidity measurement following the ISO 7027 standard, which specifies near infrared radiation at wavelengths where organic absorption is very weak, was less affected by organics. As a result, rating equations between suspended sediment and turbidity may be significantly different with ISO 7027 compared with EPA 180.1 methods.

Flights of Holocene marine terraces are useful for reconstructing past earthquakes, but coastal erosion can remove terraces from the landscape, potentially leading to incorrect estimates of earthquake magnitude and frequency. Relatively little effort has been afforded to studying terrace erosion processes, and this paper presents the first field evidence that we are aware of documenting terrace erosion rates. Two case studies from New Zealand provide a unique opportunity to observe the beginning and end phases of terrace development. We present downwear and backwear erosion measurements, showing that both sets of processes are important. Microerosion meter measurements from Kaik oura Peninsula, South Island, confirm that downwear processes are modifying new marine terraces that were created when the

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