Satellite Radar Interferometry (InSAR)an effective technique for deformation monitoring in geomatics engineering

Resumen

Many engineering infrastructures in all countries are structurally deficient. Rigorous inspection and proper monitoring of these infrastructures is vital for the safety of the citizens. These interventions are both costly and time consuming making it usually impossible to survey every one, which many times represent a high risk. Synthetic Aperture Radar Interferometry (InSAR) is a remote sensing technique very effective for the measure of small displacements of the Earth’s surface over large areas at a very low cost as compared with conventional geodetic techniques. Advanced InSAR time series algorithms for monitoring and investigating surface displacement on Earth are based on conventional radar interferometry. These techniques allow us to measure deformation with uncertainties of one millimeter per year, interpreting time series of interferometric phases at coherent point scatterers (PS) without the need for human or special equipment presence. By applying InSAR processing techniques to a series of radar images over the same region, it is possible to detect vertical displacements of infrastructures on the ground and therefore identify abnormal or excessive movement indicating potential problems requiring detailed ground investigation. A major advantage of this technology is that a single radar image, which can be obtained in darkness and in any weather, can cover a major area of up to 100 km by 100 km or even a swath width of 250 km in the case of the new Sentinel-1 C-band satellites, and therefore all engineering infrastructures in the area, such as dams, dikes, bridges, ports, etc. could be monitored reducing operating cost effectively. The new generation of high-resolution radar imagery acquired by SAR sensors such as TerraSAR-X or COSMO-SkyMed, and the development of multi-interferogram techniques has enhanced our capabilities in recent years in using InSAR. In this paper we address the applicability of using spaceborne SAR sensors for monitoring infrastructures in geomatics engineering and present several cases of study.