Accurate measurement of land elevation above sea level is an essential first step in considering the potential impacts of sea level rise.
The investigation behind the Commissioner’s recent report ‘Preparing New Zealand for rising seas’ included commissioned work from NIWA to obtain and standardise LiDAR elevation data from regional councils around the country. This data was used to produce regional land elevation maps that were published in conjunction with the Commissioner’s 2015 report.
LiDAR is a technique in which pulses of light from a laser on an aeroplane are bounced off the ground, and the time taken for the reflected pulse to return is used to measure the elevation of the ground. Topographic surveys using LiDAR are typically accurate to ten to fifteen centimetres – enough that they can be used as a basis for analysing the impacts of sea level rise.