Meteorological drought in southwest Bulgaria during the period 1961-2020 (original) (raw)
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In recent years, threats of natural origin, including those associated with the occurrence of drought is a topic that arouses interest in representatives of local government agencies, federal governmental authorities, scientific communities and residents of cities and villages. A significant part of the economy of Northern Bulgaria is agricultural, which increases the need for careful water management and planning. The aim of this study is to identify the drought hazard with regard to its spatial extends, frequency and severity and to assess the vulnerability to drought in Northern Bulgaria at the regional scale (NUTS-2). The standardized precipitation index (SPI), Standardised Precipitation-Evapotranspiration Index (SPEI) and Streamflow Drought Index (SDI) at 12-month time step for the period 1961-2012 were used to obtain drought hazard index (DHI). In order to assess drought vulnerability, Drought Vulnerability Index (DVI) was calculated based on the following parameters: population density, municipal water use, industrial water use, agricultural water use, and public water services. The results of the study show low DHI values and homogeneous distribution of drought hazard in the north part of Bulgaria. However, the drought vulnerability in the investigated area is very high due to the higher consumption of water by industry, municipal water supply, and extensive agricultural lands. Our results provide an elaborated understanding of the drought hazard and drought vulnerability and will be helpful as an early step in the development of risk-based drought management plans.
Abstract—This study assesses the vulnerability of Bulgarian agriculture to drought using the WINISAREG model and seasonal standard precipitation index SPI(2) for the period 1951-2004. This model was previously validated for maize on soils of different water holding capacity (TAW) in various locations. Simulations are performed for Plovdiv, Stara Zagora and Sofia. Results relative to Plovdiv show that in soils of large TAW (180 mm m-1) net irrigation requirements (NIRs) range 0-40 mm in wet years and 350-380 mm in dry years. In soils of small TAW (116 mm m-1), NIRs reach 440 mm in the very dry year. NIRs in Sofia are about 80 mm smaller. Rainfed maize is associated with great yield variability (29%<Cv<69%). Considering an economical relative yield decrease (RYD) threshold, 32 % of years are risky when TAW=180 mm m-1 in Plovdiv, that is double than in Sofia. In Plovdiv region reliable relationships (R2 >91%) were found for seasonal agricultural drought relating the SPI (2) fo...
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Impact on the hydrology cycle is projected to be one of the most noticeable consequences of climate change. An increase in regional dry and wet extremes has already been observed, resulting in large socioeconomic losses. The 2014 wet conditions in Bulgaria present a valuable case study for analyzing the interaction between multiple drivers that are essential for early forecasting and warning of flood events. In this paper, time series analysis of temperature, precipitation and Terrestrial Water Storage Anomaly (TWSA) is performed and cross-correlations between observations and climate variability indices are computed for a 12-year period. In Bulgaria, a positive linear temperature trend was found with precipitation and TWSA exhibiting negative trends for the period 2003–2014. The year 2014 started with a drier and warmer than usual winter followed by five consecutive wet months from March to July. We found the following long-term variations: (1) temperature showing a local minimum i...
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Bulgarian agriculture is affected by droughts and, likely, by climate change. Thus, aiming at assessing its vulnerability, this study includes a general characterization of climate variability in eight selected locations, both in northern and southern Bulgaria. Trend tests were applied to monthly precipitation, maximum and minimum temperature and to the Standardized Precipitation Index with two-month time step (SPI-2) relative to the period of 1951-2004. Negative trends were identified for precipitation and SPI-2 at various locations, mainly in the Thrace Plain, indicating that dryness is likely to be increasing in Bulgaria. The vulnerability of rainfed maize systems to drought was studied using the previously calibrated WinISAREG model and the Stewart's yield model to compute both the relative yield decrease (RYD) due to water stress and the corresponding net irrigation required to overcome those losses. Results identified a strong relation between SPI-2 for July-August (SPI-2 July-Aug) and RYD. Results also show that yield losses are higher when the soils have a smaller soil water holding capacity. For the various regions under study, thresholds for RYD were defined considering the related economic impacts and the influence of soil characteristics on the vulnerability of the rainfed maize systems. Finally, to support drought risk management, SPI-2 July-Aug thresholds were developed to be used as indicators of the economic risk of rainfed maize for various climate regions and soil groups in Bulgaria.
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Climate Variability of Drought Indices in Romania
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Irrigation and Drainage, 2007
Poland is situated in a transitory temperate climate zone; nonetheless droughts occur, posing a serious economic, social and environmental problem. The central part has the lowest precipitation in the country, where frequent meteorological and agricultural droughts occur. To estimate meteorological drought frequency in the region, the SPI methodology is used. The analysis is made using the long-term record of precipitation from 1861 to 2005 for the Bydgoszcz area, at 3-, 6-, 12-, 24-and 48-month timescales. The detailed characterization of chosen meteorological and agricultural droughts in 1991-2005 is presented in this paper. The results show that the frequency of months in which drought was identified at 3-, 6-, 12-, 24-and 48-month time scales, is about 30%. According to the equation as proposed in this study, the number of droughts of different duration in 100 years statistically is from 8 for the 48-month drought to 120 for the 3-month drought. On the basis of the analysis of the meteorological and agriculture drought in 2000, it has been shown that the 1-3 month SPI better reflects agricultural drought development than the 6-month SPI. To better understand and characterize droughts in agricultural areas additional indices should be used for the evaluation impacts of meteorological drought. Other indices need to be investigated to form a system of indices giving the best evaluation of droughts in a given region.