Georgeta Bandoc

Aridity Variability in the Last Five Decades in the Dobrogea Region, Romania

The present study constitutes a climatic approach of aridity trend analysis in the south-eastern part of Romania (Dobrogea region), over the past five decades. The analysis is based on a series of investigations on the temporal trends of certain climatic parameters that play a key role in a territorys climatic variability, such as temperature, precipitation, and potential evapotranspiration. In this respect, a series of aridity index trends (De Martonne Index, UNEP Index, and Water Deficit Index), recorded between 1961 and 2009, was analyzed, using climatic parameters provided by eight weather stations in the Dobrogea region. While the results showed that the last five decades were generally characterized by an upward climatic aridity trend (increasing temperatures and potential evapotranspiration in all considered instances), there are certain regional differences due to precipitation regime variations (higher rainfall values were recorded at four weather stations). In terms of maximum aridity conditions, the study reveals that the most critical aridity index values were reported in 1990, 2000, 2001, 2003, and 2008, especially at the weather stations located in the northern part of the Dobrogea region. The situation is slightly different in the central-southern part, where the results indicated an aridity trend decline coupled with an increase of annual precipitation amounts, especially between 1995 and 2009.

Climatic water balance dynamics over the last five decades in Romania’s most arid region, Dobrogea

The analysis of a territory’s climatic water balance dynamics against the background of climate change is a key component for increasing water resource management efficiency. The present study aims to analyse climatic water balance (CWB) dynamics in Romania’s most arid region, Dobrogea, located in the southeast. The study covers the 1961–2009 period, and is based on annual and seasonal CWB values (mm), provided by nine weather stations located throughout the region. The study, based on statistical and GIS techniques, is divided into two main stages, both carried out at annual and seasonal scales–trend analysis using the Mann-Kendall test, the Sen’s slope method, and CWB value distribution type analysis. In order to identify the probabilistic types of distributions, four mathematical models were identified–Pearson, Gamma, Chi-Squared and Wakeby, statistically verified with the P-P Plot, Q-Q Plot and Probabillity Difference Graph (PDG) curve tests. Thus, in terms of trends, the results showed a deficit increase especially at the northern stations, mainly for annual values (with a peak in the northeast, where CWB rates reached –3.2 mm/yr). While general CWB declines occurred in winter, spring and summer, apparent decrease rates were found in the northern region (highest negative rates–summer, northwest, –1.4 mm/yr). Autumn is an exception, due to overall increase rates which peaked in the southwest (2.3 mm/yr). However, the entire trend analysis indicated a general lack of statistical significance. The distribution type histogram analysis showed that, annually and seasonally, deficit values are generally dominant (more noticeable in the northern region), except for the winter season, mainly characterized by surplus intervals. Thus, the results suggest a climatic water deficit increase over the last five decades especially in northern Dobrogea, which signals the need for a spatial prioritization targeting a more efficient water resource management, necessary first and foremost for increasing regional agricultural system productivity.

Water deficit and corn productivity during the post-socialist period. Case study: Southern Oltenia drylands, Romania

ABSTRACT Water deficit (WD) typically associated with drylands and poor land use currently represent a major limiting factor for agricultural systems in numerous regions of the world. The present study aims to analyze the relationship between water deficit and corn (Zea mays L) crop yields in southern Oltenia drylands. The study includes the post-1990 period, which is representative for Romania in terms of ample climate changes and poor land planning decisions affecting water resources. This analysis targeted the vegetation period of corn (April–September), the reference period covering a 14-year interval, from 1990 to 2003. The entire analysis was based on spatialized WD data (mm), obtained by interpolation methods used on climate data provided by regional weather stations, and agricultural yield data (tons/hectare/year), recorded in 113 administrative territorial units. Both data sets were analyzed in terms of interannual statistical relationships, established in compact climate zones delineated by Thiessen-Voronoi polygons. The results showed a clear statistical relationship between the two variables, with an average dependence of corn yields on water of approximately 65%. The range was from 55 to 78%, depending on region. The results showed an average yield decrease of 16.5 kg/ha/year for each mm rise of the WD, or loss of 1.65 t/ha/year when considering a deficit rise of 100 mm. Therefore, in the context of increasing future WD, urgent action is needed in order to reintroduce irrigation systems.

Nuclear energy: Between global electricity demand, worldwide decarbonisation imperativeness, and planetary environmental implications

For decades, nuclear energy has been considered an important option for ensuring global energy security, and it has recently started being promoted as a solution for climate change mitigation. However, nuclear power remains highly controversial due to its associated risks - nuclear accidents and problematic radioactive waste management. This review aims to assess the viability of global nuclear energy economically (energy-wise), climatically and environmentally. To this end, the nuclear sectors energy- and climate-related advantages were explored alongside the downsides that mainly relate to radioactive pollution. Economically, it was found that nuclear energy is still an important power source in many countries around the world. Climatically, nuclear power is a low-carbon technology and can therefore be a viable option for the decarbonization of the worlds major economies over the following decades, if coupled with other large-scale strategies such as renewable energies. These benefits are however outweighed by the radioactive danger associated to nuclear power plants, either in the context of the nuclear accidents that have already occurred or in that of the large amounts of long-lived nuclear waste that have been growing for decades and that represent a significant environmental and societal threat.

Estimation of the Annual and Interannual Variation of Potential Evapotranspiration

Knowledge of ecological factors for all natural systems, including human-modified natural systems, is essential for determining the nature of changes in these systems and to establish interventions that must be achieved to ensure optimal functioning of these systems. The purpose of this chapter is to identify annual and interannual variations of potential evapotranspiration, in conjunction with climate changes in recent years, on the coastal region of Sfântu Gheorghe – Danube Delta. Under natural conditions, evapotranspiration flows continuously throughout the year, representing a main link in the water cycle and an important heat exchange factor affecting ecosystems. Potential evapotranspiration is the maximum amount of water likely to be produced by a soil evaporation and perspiration of plants in a climate. Real balance between the amount of precipitation fallen named P and the amount of water taken from the atmosphere as vapour, called potential evapotranspiration PET is of particular importance in characterizing climate, representing an expression of power absorption by the atmosphere and expressing quantity water on soil and vegetation that request (Henning & Henning, 1981). The difference between precipitation (P) and potential evapotranspiration (PET), i.e. P PET  known as P  is denoted by excess precipitation to PET (E) or deficit of precipitation to PET (D) if the difference is positive or, respectively, negative. The intensity of water loss through evaporation from the soil or by transpiration from the leaf surface is largely determined by vapour pressure gradient, i.e. the vapour pressure difference between leaf and soil surface and atmospheric vapour pressure (Berbecel et al, 1970). The vapour pressure gradient is determined, in turn, by the characteristics of air and soil factors, such as: radiant energy, air temperature, vertical and horizontal movements of the air saturation deficit, the degree of surface water supply evaporation, plant biology and soil characteristics. Heat factor also has a significant influence on evapotranspiration as temperature, on one hand, intensify of water vapour increases and, on the other hand, increases air capacity to maintain water vapour saturation state, reducing atmospheres evaporated power (Eagleman, 1967).

Hydroclimatic dynamics in southwestern Romania drylands over the past 50 years

The present paper examines hydroclimatic dynamics in southwestern Romania drylands, which is one of the country’s most heavily affected regions by climate change. The analysis focuses on two of the region’s representative catchments (Drincea and Desnatui), covers the past five decades (1961–2009), and is based on climate data (mean monthly and annual climatic water balance values – CWB, expressed in mm) and hydrological data (mean monthly and annual streamflow rate values – SFR, expressed in m3/s). The data were provided by five regional weather stations, i.e., by five gauging stations located within the two catchments. The analysis was conducted on three temporal scales (annual, seasonal and monthly), and used statistical methods, such as Mann–Kendall test/Sen’s slope method for trend analysis, and Spearman/Student test for the statistical association between climatic and hydrological parameters. The results indicated an overall increase in climatic water deficit, with direct effects on streamflow reduction. Statistically significant trends (climatic water deficit increase and streamflow decrease) were identified especially in spring (with maximum rate values of (−1.66 mm/yr)/(−81.3 mm/49 yrs), for the CWB, and (−0.02 m3/s/yr)/(−0.9 m3/s/49 yrs), for the SFR). In some cases (mainly in the autumn months) it was found that, while climatic water deficit has decreased, the streamflow rate has increased. Statistical correlations revealed the relationship between the considered hydroclimatic parameters, with a particularly high statistical significance in spring and summer. Weak and inverse correlations between climatic and hydrological parameters can be explained by the role of other factors controlling the streamflow, both natural (soil and lithology) and anthropogenic (wetland drainage, water body conversion, dam and reservoirs building).

Analysis of Environmental Characteristics and Operational Reports of Small and Medium Turbines

Application of environmental policies to prevent climate change, mitigation of climate change, the progressive reduction of emissions of greenhouse gases under commitments, encourage reducing energy consumption by using technologies that are efficient and support production of cheap and clean energy sources should be a priority for contemporary society. Given the above goals, the application presented in this article represents a model of how we addressed the question of the correct size of local wind turbines to provide energy coverage of a community. This method involves an analysis of environmental factors, followed by the analysis of wind in the area and continued to calculate the energy potential of the area and capable energy and wind turbines provided consumer choice