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Floods are one of the most devastating natural disasters that can lead to significant economic and environmental damage and even loss of lives. Flood hazard mapping is one of the measures of disaster risk reduction and becoming a more important function in conserving biological diversity and protected areas now and future. Most of the research is focused on determining flood risk in urbanized areas. In this paper, the protected areas affected by potential floods are studied. Protected areas are according to a directive Directive 2009/147/EC of the European Parliament and of the Council of 30 November 2009 on the conservation of wild birds and Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. The selected study area is the Batova River catchment. A large part of it is a protected area under both directives and there are recorded a lot of significant floods. The software product HEC-RAS, version 6.0, was used to determine the flooded areas. Flood maps are created for three scenarios: 20-, 100- and 1000-years. The data used to simulate flash floods are precipitation from monitoring network of the National Institute of Meteorology and Hydrology (NIMH), a Digital terrain model with pixel cell 6/6m from Military Geographical Service at the Ministry of Defense of the Republic of Bulgaria and land cover data from CORINE Land Cover 2018. As a result of the modeling, the inundated areas during rain with different return period have been determined. An analysis was made of the extent to which they affect the protected areas. This approach can also be applied to other watersheds. Based on these studies, an appropriate set of measures could be drawn up to protect these areas and the endangered species whose habitats fall within them and contribute to the preparation of Flood Risk Management Plans. By integrating floodplain management and wildlife conservation, such as the protection of habitat communities have the opportunity to reduce flood risk, and protect species and their habitat while enjoying the natural resources. [ABSTRACT FROM AUTHOR]

Transitional (brackish) water bodies host extremely vulnerable ecosystems. They are highly sensitive to pollution, changes in the water currents, nutrient levels, etc. Over the course of the 20th century in Bulgaria, many of them were purposely drained or strongly altered. Today, these fragile ecosystems account for just 0.1% of Bulgaria’s area, and hence they are listed among the country’s top priority nature conservation sites. The long-term preservation and survival of numerous rare or threatened hydrobionts depend on the conservation of these aquatic habitats. The site selected for the study herein is Maznia azmak. It represents a highly eutrophicated coastal lake (a former river bed) found in the Kamchia River’s downstream sector, contiguous to the mouth of the estuarine type, where it empties into the Black Sea. The study site represents a constituent part of Kamchia Nature Reserve and two Natura 2000 protected sites, i.e., BG0002045 Komplex Kamchia (Birds Directive) and BG0000116 Kamchia (Habitats Directive). The main goal of the present paper is to analyze the spatio-temporal changes, scale and rate of eutrophication at Maznia azmak and the related loss of sensitive aquatic habitats that are a subject to preservation. This has been achieved through GIS-based analysis and interpretation of archive topographic maps compiled at scale of 1:5,000-1:126,000, historical satellite and contemporary drone imagery. Results of the study demonstrate the constant expansion of the aquatic vegetation at the expense of open water surfaces. These findings imply for a deteriorated ecological status of the associated freshwater habitats in result of eutrophication. [ABSTRACT FROM AUTHOR]