The surface movement in the Krimpenerwaard polder in The Netherlands results from primary or hydrodynamic settlement/swelling, secondary or creep settlement/swelling, and peat oxidation. We used surface movement measurements in a Bayesian inversion scheme to disentangle the contribution of these three processes to the subsidence. The prior information, including spatial correlations, appeared to be crucial in our procedure. This prior information was derived from geological modeling incorporating the most important uncertainties. The inversion procedure allowed us to quantify the contributions of the three processes with unprecedented accuracy. Surface rise in the data was related to swelling of the clay layers, even though swelling was considered infeasible in the prior information. Despite this, the irreversible nature of peat oxidation was preserved. The improved subsurface description offers prospects for identification of incorrect information and for better assessments of the effects of water management.@en

As part of the Terrafirma Validation Experiment a comparison of Persistent Scatterer Interferometry (PSI) with in-situ measurements is performed. The experiment purports to validate the processing chains of partners participating in the Terrafirma project, in order to obtain a better understanding of the performance of the techniques. Two test sites are chosen in the Netherlands: (i) the trajectory of a subway line in the centre of Amsterdam, still to be constructed, and (ii) the area around the city of Alkmaar, affected by subsidence due to gas extraction. The Amsterdam site is monitored using Envisat-ASAR data, whereas for the Alkmaar area both ERS1/2-AMI and Envisat-ASAR data sets are used. Due to the difference in deformation phenomena, available ground truth and surface characteristics, different validation procedures are applied to the two test sites. Here we describe these validation methodologies and the validation results.

@en