Monitoring the Evolution of the Kaiwhata Landslide in New Zealand using Object-based Image Analysis and Sentinel-2 Time Series

Abstract

Landslides are among the most serious geological hazards in mountainous and hilly areas of New Zealand, where they frequently cause significant damage and landscape changes. Monitoring the evolution of landslides and their consequences can help to mitigate hazards that could arise in later reactivation phases or in similar cases. The abundance of time-series remote sensing data has facilitated the mapping and monitoring of landslides. By applying object-based image analysis (OBIA) and using Sentinel-2 satellite data from 2017 to 2021, we aim to semi-automatically map the evolution of the Kaiwhata landslide and the subsequent impacts on the upstream area in the Wairarapa region in New Zealand. The OBIA mapping results revealed a gradual increase in the landslide area, with two major changes in June 2019 and November 2020. These major changes were followed by the formation of temporary landslide-dammed upstream lakes along the Kaiwhata river.