Floods with Debris and Anthropogenic Waste: Accounted for or Not?

Natural floods are unusual extreme events resulting from significant or prolonged rainfall, which sometimes turn into disasters. Trends indicate that these phenomena may become more frequent in the future. Therefore, many solutions are being implemented in practice to deal with the problem. In the European Union, enhanced measures have been taken, including the assessment and mapping of flood risks, triggered by the adopted legislation. Despite these solutions, flood disasters continue to occur, even in areas included in Flood Risk Management Plans but outside the territories designated as vulnerable. To investigate the reason, a study was conducted accounting for flood genesis and the role of flood debris and anthropogenic waste as a factor that can worsen the harmful impact of these events. It was considered whether there is a gap in the application of current methods and legislation. A brief review was performed concerning the physical description of the phenomenon and the evaluation methods used, accounting for the role that debris and anthropogenic waste play in them. Some main practices and applicable tools were also discussed in brief. As an illustration of the impact, a case study of a recent significant flood in Bulgaria was also presented. This flood affected an area that is not identified as at risk under the Flood Risk Management Plans developed in accordance with the European and Bulgarian legislation and requirements. The information presented here confirms the significant role that debris and anthropogenic waste play in the process of turning a flood into a disaster and highlights the need for additional work concerning their proper incorporation in both the regulation and assessment processes.