Measuring erosion rates using the micro-erosion meter: 20 years of data from shore platforms, Kaikoura Peninsula, South Island, New Zealand

Abstract

Fifteen micro-erosion meter sites, giving 42 individual readings of erosion were remeasured twenty years after installation on mudstone and limestone shore platforms on the Kaikoura Peninsula, South Island, New Zealand. The mean annual surface lowering rate was calculated to be 1.43 mm/yr. Longer term data were compared to shorter term data collected over a two-year period between 1973 and 1975 to test the validity of extrapolating average erosion rates from shorter term data. It was found that the average lowering rate for the shorter term data were in statistically acceptable agreement with those for the longer term data. Extrapolation of short term micro-erosion meter data is therefore acceptable in this particular environment. In previous work it has been suggested that measurements from as few as thirty individual micro-erosion meter positions are required to calculate a mean annual lowering rate on shore platforms. Measurements from 30 MEM positions provided an statistically acceptable mean annual lowering rate for shore platforms on the Kaikoura Peninsula.