Near real-time SAR-based processing to support flood monitoring

Abstract

Earth Observation has proven to be a synoptic and objective source of information to derive crisis and damage maps. In case of flood events, often characterized by weather conditions which prevent the possibility of exploiting data acquired by optical sensors, synthetic aperture radar (SAR) sensors become the only space-born source of information due to their all-weather capability. In order to assure the delivery of damage maps as soon as possible after a disaster, the access and the exploitation of SAR data must be accelerated and simplified with respect to the current procedures. In this context, two issues needed to be addressed: fast access to large data archives, and provision of near real-time on demand processing services. This paper presents a near real-time SAR processing service to support the mapping of flooded areas. The service exploits Grid technology to manage large volumes of data and to provide the computational resources to cope with SAR processing demanding tasks. The algorithm for the implemented orthorectification of the final products is presented. The validation of the derived products shows a reliable accuracy for co-registration of half a pixel. The geolocation accuracy resulted below 100 m. The service makes a significant contribution to accelerating the access and exploitation of ESA SAR data.

Azimuth Ambiguities Removal in Littoral Zones Based on Multi-Temporal SAR Images

“…The use of RGB composition in multi-temporal SAR image analysis has been already presented for flood mapping [28,29]. However, there has rarely been a study on RGB composition for azimuth ambiguities [11].…”

Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model

“…The appropriateness of the ASAR data for flood mapping and herbaceous wetlands monitoring has been widely reported. Some examples can be found in [28][29][30][31][32][33][34].…”

The Use of Radar Imagery in Riverine Flood Inundation Studies

“…However, as far as is known, operational systems for near real-time supply of geo-located high resolution SAR data to users (analogous to ESA-ESRIN's FAIRE system for ASAR/ERS-2 data, which delivers processed geo-registered images to users in about three hours (Cossu et al, 2009)) have still to be developed. In order to ensure that a SAR image was obtained in near real-time, it would be necessary to minimise the time delay between an overpass and the production of the resulting SAR flood extent.…”