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Reproducing the hydrological process of river runoff is a fundamental part of water resources planning and management. Finding a mathematical model to reproduce the runoff time series aims not only to extract maximum information from the limited available data, but also to extrapolate into the future by representatively generating the historical runoff process. Almost all management decisions are based on forecasts. Our present is characterized by the increasingly frequent occurrence of hydrometeorological process...

A classical approach to the assessment of the available water resources for different users, including environmental, in Europe is the Catchment Abstraction Management Strategy (CAMS). An assessment has to be made of the extent, to which natural runoff regime could be changed without affecting the sustainable functioning of the environment. The aim of the Restoring Sustainable Abstraction (RSA) is to identify over-abstraction in rivers and wetland sites and make the abstraction sustainable again. In this regard, t...

Climate factors are already exerting negative pressure on water resources, society and ecosystems. The analysis of trends and identification of vulnerable water supply areas is related to the River Basin Management Plans. For this end, a methodology for assessment of water resources vulnerability, developed in international projects of the National Institute of Meteorology and Hydrology (NIMH), is adapted. The methodology is further developed by drought risk assessment. The main stages are: 1) Assessment of the cl...

Water resource of a given river basin is the main component of the ecosystem and water resources management system as well. Ecological flows are considered within the context of the Water Framework Directive (WFD) as -a hydrological regime consistent with the achievement of the environmental objectives of the WFD in natural surface water bodies as mentioned in Article 4(1). The so-called Heavily Modified Water Bodies (HMWB) or -regulated rivers- have modified flow, which is influenced by reservoir compensation rel...

The development of indicator systems for drought identification is part of the Drought Management Plans. The analysis of the correlation between the different indices is an essential part of the indicator systems. That research is part of a task related to the developed at NIMH system (http://hydro.bg) of drought indicators and the development of recommendations for their simultaneous use. For this purpose, the influence of climatic factors on the hydrological cycle components and the role of the characteristics o...

Drought indicator systems help decision-makers to understand how and where the drought occurred and to take measures from the Drought Management Plans. The main goal in the Water Framework Directive (WFD) is the achievement -good ecological status-, but the Article 4.6 allows temporary deterioration of the status, occurred as a result of so called -prolonged drought-. Reduction of natural water resources such as rivers, lakes, aquifers, is associated with the reduction in available water resources for water supply...

Modeling is important for river system analysis and management. The aim of the research is to apply disaggregation models to data with recovered natural river flow of Osam River located in North Bulgaria. As a result river discharge synthetic sequences are generated on monthly and seasonal discretization. We want to test applicability of the models for specific climatic, hydrological and orographic conditions in Bulgaria. Disaggregation models are from the family of stochastic models. Disaggregation models could b...

The updating of the used inflow data to the reservoirs from Annex 1 of the Water Act has been developed for the needs of the Ministry of Environment and Water (MoEW) and for the annual schedules of their water use. Monthly inflow with a certain probability of exceedance (PE - 50%, 75%, 95%) were estimated. The results of the development are uploaded to the MoEW website(https://www.moew.government.bg).In the report are presented and new unpublished results of the annual security assessments - annually inflows with ...

Water resources are vulnerable not only from climate change, but from many other socio-economic drivers of change. According to the Intergovernmental Panel on Climate Change ?Vulnerability is the degree, to which a system is susceptible to, or unable to cope with adverse effects of climate change, including climate variability and extremes?. When a trend towards decreased precipitation and runoff coincides with a trend towards higher water consumption or deteriorated water quality, then the given region or river b...