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The topic of this report concerns the expected changes of the important part of the water resources of Bulgaria caused by the moving of the main precipitation to the warm seasons. The study examines the influence of the air temperature and rain intensity as main factors for the change in the potential groundwater recharge / precipitation ratio in the summer months of three recent years on the territory of Southwest Bulgaria (Basins of Struma and Mesta rivers). The assessment has been performed by application of a precipitation-runoff hydrological model, which is a sub-model of NASA’s climate model., Proceeding of 1st International Conference on Environmental Protection and Disaster RISKs, 2020, p. 577-585

Debris flows occur in many areas in Bulgaria, but the studies of these cases are mainly for their structure and insensitivity and less attention is given to the susceptibility and risk assessment. Although the development of computer technology, geoinformation approach in debris flows investigation in Bulgaria is still not wide applied. The current study focuses on the geological-geomorphological features of the debris flows areas and their role in mass movement. Morphometric characteristics of the basins and rivers/streams channels are analyzed in relation of slope hydrologic properties and mass movement. Lithological substrate and land cover are also considered. Normalized difference vegetation index is used for assessment of land cover and outlining the debris flows areas. The research is held on the foothills of Pirin Mountains (Bulgaria). In the area steep slopes, deep weathering and many faults are highly presented, which, combined with sparsely vegetation and intensive rainfall determine the frequent occurrence of debris flows. GIS analyses are done on the base of SRTM digital elevation model, Sentinel 2 images (ESA), geological map in cale 1:100 000 and field investigations. Application of GIS technology provides an opportunity for easy performing of spatial analyses and investigating the functional and spatial relations between different aspects of debris flow environment. The results of the research can be used in debris flows susceptibility assessment and mapping which is a first step in disaster risk reduction and management.

In the east part of the Republic of Croatia there is an agricultural area with a long tradition. This area is part of the Sava valley which natural features were created long time ago. But, in the last few hundred years these natural features were significantly modified by human activities. This area has continental climate and relatively little rainfall. Hydrographic backbone of the newly formed valley is the Bosut River with its few major tributaries (Biđ River and Spačva River). Biđ-Bosut basin extends to the field of three Croatian counties, and it is in the backbone of life for a number of their municipalities. The lower part of the basin is located in the Republic of Serbia and is the life part of the local population. Biđ-Bosut basin ones were swampy and forested lowland area on the civilization crossroads. Then it becomes mainly an agricultural area, been developed within a united state on the basis of socialistic planning and state ownership. Today this area is marked by damage and neglect of previously built hydropower system. Also, valley is marked with the adaptation and extension of the divided basin which is situated on the border of the three neighbor states with different hydrotechnical organization. This paper describes the climate, hydrological and morphological characteristics of the Biđ-Bosut basin and its complex hydrotechnical system. The agricultural production in this area is aided by developed amelioration drainage, but runoff in the basin is very specifically. River beds are regulated, slopes of them are very small, and many local population do not know the name of the individual streams and direction of its water flows. Paper also points out the specific problem in this region in the period of small and high water, and the possible challenges due to climate changes and adaptations for survival. The local challenges are also social relations where benefits and adversity can contribute to the unification or misunderstanding between neighbor countries.