Development and testing of a method to monitor peatland subsidence in the Waikato region

Abstract

The Waikato region has about 84,000 ha of peatlands, of which about 65,000 ha has been drained, mostly for agriculture, resulting in shrinkage, consolidation and oxidation of the organic soil. These three processes are collectively called peat subsidence, which is a gradual lowering of the land surface.

Waikato Regional Council require robust spatial information on regional peatland subsidence rates and spatial variation, and contracted Manaaki Whenua – Landcare Research (in collaboration with the University of Waikato) to develop a new Waikato regional peat subsidence monitoring network for peatlands under agriculture.

This report documents the method development phase. This includes testing of airborne light detection and ranging (LiDAR) and global navigation satellite system (GNSS) surface survey. It also examines the value and limitations of integrating historic peat depth data and provide evidence for the occurrence and the magnitude of seasonal peat surface oscillation (PSO).