Monitoring the water table depth with Sentinel-1 intensity time series for peatlands in Germany

Abstract:
The water table depth (WTD) of a peatland has a strong influence on the climate balance of this ecosystem and should therefore be monitored especially before and after rewetting measures to assess their performance. This paper deals with the estimation of the WTD in two peatland sites using a Sentinel-1 intensity time series in VV and VH polarisation over three years. Two percolation peatlands, one drained and one rewetted, are examined in detail. The WTD data are correlated on the one hand with the intensity values (σ⁰) of the same day, and on the other hand with σ⁰ interpolated to daily values. In addition, different water levels are considered in order to analyse the limitation of the data for drained sites. The highest correlation of the data is found with a Pearson correlation coefficient of 0.79 between the water levels above -40 cm depth and the σ⁰-VV mean values over a reference area of approx. half a hectare for the drained peatland.