InSAR Maps Peatlands in the Waikato Region of New Zealand

We use remote sensing techniques to map the extent of peatland organic soils in the Waikato Region of New Zealand based on surface subsidence. Both interferometric synthetic aperture radar (InSAR) and digital elevation model (DEM) differencing indicate subsidence occurred between 2013 and 2024 within previously mapped organic soil boundaries. Both the mapped extent and oscillating surface elevation of organic soils derived from InSAR time series align with ground‐based observations. The primary driver of subsidence is the artificial drainage of organic soils for agriculture. This has significant environmental implications for soil conservation, climate change mitigation, water quality and flood risk management. Our findings demonstrate that satellite‐based approaches offer an efficient and scalable method for mapping organic soil that complements ground‐based approaches. More moderate subsidence is apparent in low‐relief, flood‐prone areas beyond mapped organic soils in the Hauraki Plains. However, further validation is needed due to possible fading signal effects in vegetated areas. InSAR fading signal or phase bias is known to cause the overestimation of rates on grassland and cropland and additional work is required to determine the accuracy of mean subsidence rates reported in this study.