Monitoring the September 2010 floods

Centre of Excellence Space-SI has successfully and efficiently integrated accurate meteorological predictions with the acquisition and analysis of satellite data in the early stages of its operation. By combining existing data, real time satellite image acquisition and processing we are helping coordinate actions in the event of a natural disaster.

National Meteorological Service of Slovenia predicted the quantity, time and location of the disastrous floods with extreme accuracy and sent a warning to the Administration for Civil Protection and Disaster Relief (ACPDR). They in turn activated project SAFER and in collaboration with the Centre of Excellence and Scientific Research Centre of the Slovenian Academy of Sciences and Arts (SRC SASA) also activated the international program Space and Major Disasters. Under both initiatives the Centre of Excellence received 13 optical and radar satellite images of central and southern Slovenia from different space agencies, which enabled us to map flood status and dynamics in karstic fields and Ljubljana marshes with their surroundings.

First, the images were precisely placed in the national coordinate system and discrepancies due to different observation angles eliminated by orthorectification. As water is very dark in radar images we labeled it fairly easily by determining reflection threshold, classification and advanced filtering, and sent the results to ACPDR. The series of images enabled monitoring of flood extent in the interval of a few days. The results of radar recordings did not sense flooding in urban environments due to the nature of the recording system and furthermore, the extent of flooded areas was underestimated in regions where tall-grown crops and trees alternated with fields of short-grown crops or meadows in narrow intervals.

An individual satellite image can be processed fairly quickly, but that still demands the presence and decision-making of a professional. Therefore, the Centre of Excellence is developing technology for (nearly) automated processing which will significantly shorten processing time, but mostly it will allow immediate publishing of the interpreted results as an online map. During observation of this year’s floods we have encountered difficulties both in data acquisition and the (in)ability of satellite control which resulted in irregular and delayed data reception. Most importantly, it needs to be stressed that we could not influence recording of the area nor the frequency of observation.

The potential of almost real time data analysis comes to life only through immediate online data delivery. Therefore, an important part of the Centre of Excellence’s activities is an online portal which will be the final destination for product delivery. A part of the portal will be aimed at the general public and lay users.