Quantifying mass loss in raised bogs and heathlands in the central-northern United Kingdom from satellite-geodetic uplift rates

Since decades, even centuries, blanket and raised bogs in the central-northern United Kingdom have been exposed to climatic and anthropogenic stressors like drainage, land management, evapotranspiration, peat extraction and/or atmospheric pollution. As a result, those landscapes undergo substantial mass changes and soil compaction, but the quantification of these processes remains a challenge: In-situ observations are cost-extensive and/or often biased due to an unstable local measurement reference.

To overcome this, we analyze remotely-sensed surface uplift rates from the European Ground Motion Service (EGMS) that were extracted from four years (2019-2023) of radar-interferometric (InSAR) time-series. We also consulted point-wise uplift rates from two decades of positioning (GNSS) measurements to reference ongoing bedrock uplift. We validate these observations with analytical models that mimic a the load response while also accounting for a remaining glacial isostatic adjustment.

The surface rate maps show ~50 km-wide uplift bulges that correlate with land classified as heathlands and bogs. Maximum uplift surrounding the heather/bogs reaches 2-7 mm/yr. The bogs/heathlands themselves, however, exhibit distinct subsidence due to mass loss (carbon, water) of up to 10 mm/yr, which is already corrected for the simultaneous bedrock uplift due to unloading. Based on these observations, we can reproduce the spatial bedrock uplift pattern with our load model. The explanation of the signal amplitudes requires further fine-tuning of the model parameters and a better understanding of the in-situ bio-chemical processes. This approach will enable us to quantify the amount of water-vs.-carbon loss in this particular landscape.