Suitable estimation of the land subsidence is crucial in deltas and coastal areas, where the climate variability effects (e.g., frequent and intense rain storms, peaks in river discharge and sea level fluctuations), coupled with natural or anthropogenic land sinking, represent serious factors of inundation risk. Nowadays, continuous GNSS (Global Navigation Satellite Systems) networks have become precision monitoring tools of the ground displacement. Customarely GNSS site-position time series exhibit a linear trend plus seasonal oscillations of annual and semi-annual periods. These periodic variations may be due to the joint contributions of surface mass redistribution (atmosphere, ocean, snow and soil moisture), frequently masked by the superposition of several correlated or uncorrelated noise sources. These signals have to be recognised and properly modelled in order to estimate the vertical ground lowering. Several authors investigate the seasonal component by using the “peering approach”, which is based on the comparison between the joint contribution of established individual geophysical sources (not removed during the data processing phase) and the observed seasonal variations. This approach allows to quantify influence, distribution and magnitude of the individual sources and to understand the main processes affecting the geodetic time series. Differently from this approach, we propose a procedure based on two steps: multi-disciplinary and multi-methodological comparative analyses are first performed for selecting the physical mechanism (individual source) that better explain the seasonal signals clearly exhibited by the GPS time series. Then, a physically-based model is used for enhancing the extraction of the geodetic trend and thus estimating the geodetic velocity without seasonal oscillations. The proposed approach is applied to the Codigoro test site (southern part of the Po Delta – Northern Italy), which is an area historically affected by both anthropogenic and natural subsidence and influenced by climatic changes.

Hydrological model for retrieving subsidence velocity from GPS data: application to Po Delta area

VITAGLIANO E.;DI MAIO R.;PIEGARI E.;RICCARDI U.;
2018

Abstract

Suitable estimation of the land subsidence is crucial in deltas and coastal areas, where the climate variability effects (e.g., frequent and intense rain storms, peaks in river discharge and sea level fluctuations), coupled with natural or anthropogenic land sinking, represent serious factors of inundation risk. Nowadays, continuous GNSS (Global Navigation Satellite Systems) networks have become precision monitoring tools of the ground displacement. Customarely GNSS site-position time series exhibit a linear trend plus seasonal oscillations of annual and semi-annual periods. These periodic variations may be due to the joint contributions of surface mass redistribution (atmosphere, ocean, snow and soil moisture), frequently masked by the superposition of several correlated or uncorrelated noise sources. These signals have to be recognised and properly modelled in order to estimate the vertical ground lowering. Several authors investigate the seasonal component by using the “peering approach”, which is based on the comparison between the joint contribution of established individual geophysical sources (not removed during the data processing phase) and the observed seasonal variations. This approach allows to quantify influence, distribution and magnitude of the individual sources and to understand the main processes affecting the geodetic time series. Differently from this approach, we propose a procedure based on two steps: multi-disciplinary and multi-methodological comparative analyses are first performed for selecting the physical mechanism (individual source) that better explain the seasonal signals clearly exhibited by the GPS time series. Then, a physically-based model is used for enhancing the extraction of the geodetic trend and thus estimating the geodetic velocity without seasonal oscillations. The proposed approach is applied to the Codigoro test site (southern part of the Po Delta – Northern Italy), which is an area historically affected by both anthropogenic and natural subsidence and influenced by climatic changes.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11588/739972
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