An operational open source approach for watersheds delimitation and characterization based on digital images and geographical databases

Since natural disasters may cause big human and material losses, the Brazilian government are specially interested in ways to avoid it. Among these ways, the use of computational technologies are specially interesting for monitoring and warning population about such disasters. At this work we present an approach, developed at the Brazilian National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN), for watershed areas delimitation and characterization, based on digital images and geographical databases, using only open source tools. The proposed approach achieves consistent and useful results on operation environment, providing a significant helping for disasters management. Finally, we present some examples of delimited and characterized watersheds, in different regions of Brazil, including one in the Amazon rainforest area. The presented approach is already operational at the situation room in CEMADEN.