Stochastic Environmental Research and Risk Assessment, 2017
The analysis of phenological changes in vegetation is essential for the assessment of the respons... more The analysis of phenological changes in vegetation is essential for the assessment of the response and adaptation of ecosystems/agro-ecosystems to climate change. This study analyses spatial and temporal changes in phenological events (phenophases) and in the climatic growing season in southern and southeastern Romania, based on mean monthly temperature values recorded between 1961 and 2010 at 24 weather stations, spread out uniformly in the study area. By using the histophenogram method for extracting the mean phenophases length (eight in total, i.e. growing season onset, budding-leafing, flowering, fruiting, maturing, dissemination, start of leaf loss and end of leaf loss) and that of the overall growing season, this paper aims to analyse current phenological changes (in
The analysis of a territory’s climatic water balance dynamics against the background of climate c... more 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.
Land degradation, a current environmental threat of global proportions, is a complex issue which ... more Land degradation, a current environmental threat of global proportions, is a complex issue which needs an interdisciplinary approach in order to tackle a given territory's sensitivity to the process. This study aims to spatially analyse the land degradation sensitivity in southwestern Romania, a region currently known for this type of environmental deterioration. The analysis is based on mapping and assessing land susceptibility to degradation by means of a multifactorial approach using GIS techniques, such as the well-established MEDALUS (Mediterranean Desertification and Land Use) method. Widely used in the Mediterranean region and other areas worldwide due to advantageous features such as simplicity, flexibility and rapid implementation, the method was used in this study for the analysis of the main indicators identified to be driving forces of land degradation, i.e. Climate Quality Index, Soil Quality Index, Vegetation Quality Index and Management Quality Index. The paper aims to adjust the method in relation to local conditions by considering certain additional variables (sub-indicators) for computing the main indicators, as well as by integrating a new regionally relevant indicator for this environmental issue-Water Quality Index. The final results, assessed with the proposed Land Degradation Sensitivity Index (based on 21 sub-indicators, of which 15 are included in the original MEDALUS method, and 6 are additional), showed that approximately 70% of the total study area is critically sensitive to degradation, mainly due to high agricultural pressures and very low vegetation cover. Surprisingly, in terms of administration, it was found that N80% of the region's territorial administrative units include sectors which are critically exposed to degradation that exceed half their area. The results can constitute a basic support for regional-level decision makers who can implement the appropriate measures in order to attenuate the restrictive environmental conditions.
The present paper examines hydroclimatic dynamics in southwestern Romania drylands, which is one ... more 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 m 3 /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 m 3 /s/yr)/(−0.9 m 3 /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).
Stochastic Environmental Research and Risk Assessment, 2016
Climate change analysis is essential, considering the numerous economic and ecological implicatio... more Climate change analysis is essential, considering the numerous economic and ecological implications of this critical global environmental issue. This paper analyzes the spatial and temporal trends of mean air temperature in Romania's most important agricultural area, the south and southeastern region, between 1961 and 2009. In this respect, multiannual (the entire period) and multidecadal (1961-1990, 1971-2000, 1981-2009) trends were analyzed using the Mann-Kendall test and Sen's slope method at 23 weather stations, annually, seasonally and for the growing season of the region's main agricultural crops (maize and wheat). Multiannually, the results showed statistically significant temperature increases, on all temporal scales (maximum rate of 0.06°C/year recorded in summer, equivalent to a net temperature rise of 2.82°C), except for the autumn season (cooling without statistical significance). Multidecadally, the 1961-1990 period is marked by a general cooling, especially in autumn (maximum values of-0.07°C/year or over 2°C net cooling). In the 1971-2000 and 1981-2009 periods, a general warming was observed (maximum in summer for both multidecades, when positive rates peaked at 0.09°C/year, or 2.5-3°C net warming), but the warming of the last three decades is the most prominent in terms of spatial average magnitude and trend significance. Upon analysis of the impact of climate warming on agricultural yields (maize) through linear regression, in the 1991-2000 decade, considered as case study, it was found that in 32 % of the total analyzed area there are evident relationships between the two variables (p value \0.05). In this case, a dependency of 33-50 % (40 %, on average) of maize to climate was found, and a sensitivity (loss) ranging between 0.9 and 1.5 t/ha/year (1.2 t/ha/year, on average) for a 1°C temperature rise. At the same time, significant losses (of up to 1.7 t/ha/year) of maize for a 1°C temperature rise were identified in 51 % of the area, but with little p value significance (between 0.05 and 0.1). It is however necessary to analyse the agro-climatic results cautiously, considering that only one decade of climate-agriculture relationship was studied. The results can be useful first and foremost for mitigating the climate change impact on agricultural systems, by prioritizing future adaptation strategies enforced by policy makers.
Carpathian journal of earth and environmental sciences
This paper attempts to analyze the potential relationship between the climatic water deficit of t... more This paper attempts to analyze the potential relationship between the climatic water deficit of the vegetation period of corn (April-September) and its agricultural yield, recorded in the Dobrogea plateau between 1990 and 2003. The data included in this study comprise spatialized climatic water deficit values (mm) (computed as the difference between precipitation and potential evapotranspiration), obtained through interpolation methods based on ten regional weather stations and corn crop yield data (t/ha/year) in 99 territorial administrative units, almost entirely overlapping the analyzed geographical region. The study essentially aims to identify the statistical connection between the independent variable (climatic water deficit) and the dependent one (agricultural yield) over 14 years - to this end, a series of detailed statistical correlations were applied to both variables. The results showed a statistically significant relationship especially in the plateau’s central-southern ...
Nowadays, Southwestern Romania faces a large-scale aridization of the climate, revealed by the ri... more Nowadays, Southwestern Romania faces a large-scale aridization of the climate, revealed by the rise of temperatures and the decline of the amount of precipitations, with negative effects visible, among others, in the desiccation of forest vegetation. The present study means to identify the changes that occurred, quality-wise, in the past two decades (1990-2011) in forest vegetation in Southwestern Romania, and to establish the link between those changes and extant thermal stress in the region, whose particular features are high average annual and seasonal temperatures. In order to capture the evolution in time of climate aridization, a first step consisted in using climate data, the temperature and precipitation parameters from three weather stations; these parameters were analyzed both individually and as aridity indexes (De Martonne and UNEP). In order to quantify the changes in forest vegetation, NDVI indexes were used and analyzed, starting off from Landsat satellite images, acquired at three distinct moments in time, 1990, 2000 and 2011. In order to identify the link between the changes of NDVI index values and regional thermal stress, a yardstick of climate changes, statistical correlations were established between the peak values of average annual temperatures, represented in space, and negative changes in the NDVI index, as revealed by the change-detection analysis. The results obtained indicated there is an obvious (statistically significant) connection between thermal stress and the desiccation (degradation) of forest species in the analyzed area, with false acacia (Robinia Pseudoacacia) the main species to be impacted.
Journal of environmental health science & engineering, Jan 6, 2014
In the past few decades, global climate change has accentuated the intensification of aridization... more In the past few decades, global climate change has accentuated the intensification of aridization in South-Western Romania, with direct and indirect consequences on the quality of forest ecosystems. In addition to qualitative deterioration, the quantitative changes brought about by intensive anthropic deforestation have created the conditions for a decline in the size of forest areas on vast tracts of land. The paper aims to analyze the qualitative and quantitative changes in the forest ecosystems in South-Western Romania, changes due to the synergic context of the global climate changes and the anthropic pressures of the past three decades. In order to capture the evolution of aridization in the study area, specific aridization indexes have been calculated, such as the De Martonne index and the UNEP aridity index. 1990 and 2011 satellite images have been used in order to quantify the qualitative changes. The results obtained indicated that, in the past two decades, the quality of t...
Journal of environmental health science & engineering, Jan 24, 2013
The report released by the Intergovernmental Committee for Climate Change indicates that Romania ... more The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation inde...
The beginning of the atomic age marked the outset of nuclear weapons testing, which is responsibl... more The beginning of the atomic age marked the outset of nuclear weapons testing, which is responsible for the radioactive contamination of a large number of sites worldwide. The paper aims to analyze nuclear weapons tests conducted in the second half of the twentieth century, highlighting the impact of radioactive pollution on the atmospheric, aquatic, and underground environments. Special attention was given to the concentration of main radioactive isotopes which were released, such as 14 C, 137 Cs, and 90 Sr, generally stored in the atmosphere and marine environment. In addition, an attempt was made to trace the spatial delimitation of the most heavily contaminated sites worldwide, and to note the human exposure which has caused a significantly increased incidence of thyroidal cancer locally and regionally. The United States is one of the important examples of assessing the correlation between the increase in the thyroid cancer incidence rate and the continental-scale radioactive contamination with 131 I, a radioactive isotope which was released in large amounts during the nuclear tests carried out in the main test site, Nevada.
Stochastic Environmental Research and Risk Assessment, 2017
The analysis of phenological changes in vegetation is essential for the assessment of the respons... more The analysis of phenological changes in vegetation is essential for the assessment of the response and adaptation of ecosystems/agro-ecosystems to climate change. This study analyses spatial and temporal changes in phenological events (phenophases) and in the climatic growing season in southern and southeastern Romania, based on mean monthly temperature values recorded between 1961 and 2010 at 24 weather stations, spread out uniformly in the study area. By using the histophenogram method for extracting the mean phenophases length (eight in total, i.e. growing season onset, budding-leafing, flowering, fruiting, maturing, dissemination, start of leaf loss and end of leaf loss) and that of the overall growing season, this paper aims to analyse current phenological changes (in
The analysis of a territory’s climatic water balance dynamics against the background of climate c... more 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.
Land degradation, a current environmental threat of global proportions, is a complex issue which ... more Land degradation, a current environmental threat of global proportions, is a complex issue which needs an interdisciplinary approach in order to tackle a given territory's sensitivity to the process. This study aims to spatially analyse the land degradation sensitivity in southwestern Romania, a region currently known for this type of environmental deterioration. The analysis is based on mapping and assessing land susceptibility to degradation by means of a multifactorial approach using GIS techniques, such as the well-established MEDALUS (Mediterranean Desertification and Land Use) method. Widely used in the Mediterranean region and other areas worldwide due to advantageous features such as simplicity, flexibility and rapid implementation, the method was used in this study for the analysis of the main indicators identified to be driving forces of land degradation, i.e. Climate Quality Index, Soil Quality Index, Vegetation Quality Index and Management Quality Index. The paper aims to adjust the method in relation to local conditions by considering certain additional variables (sub-indicators) for computing the main indicators, as well as by integrating a new regionally relevant indicator for this environmental issue-Water Quality Index. The final results, assessed with the proposed Land Degradation Sensitivity Index (based on 21 sub-indicators, of which 15 are included in the original MEDALUS method, and 6 are additional), showed that approximately 70% of the total study area is critically sensitive to degradation, mainly due to high agricultural pressures and very low vegetation cover. Surprisingly, in terms of administration, it was found that N80% of the region's territorial administrative units include sectors which are critically exposed to degradation that exceed half their area. The results can constitute a basic support for regional-level decision makers who can implement the appropriate measures in order to attenuate the restrictive environmental conditions.
The present paper examines hydroclimatic dynamics in southwestern Romania drylands, which is one ... more 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 m 3 /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 m 3 /s/yr)/(−0.9 m 3 /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).
Stochastic Environmental Research and Risk Assessment, 2016
Climate change analysis is essential, considering the numerous economic and ecological implicatio... more Climate change analysis is essential, considering the numerous economic and ecological implications of this critical global environmental issue. This paper analyzes the spatial and temporal trends of mean air temperature in Romania's most important agricultural area, the south and southeastern region, between 1961 and 2009. In this respect, multiannual (the entire period) and multidecadal (1961-1990, 1971-2000, 1981-2009) trends were analyzed using the Mann-Kendall test and Sen's slope method at 23 weather stations, annually, seasonally and for the growing season of the region's main agricultural crops (maize and wheat). Multiannually, the results showed statistically significant temperature increases, on all temporal scales (maximum rate of 0.06°C/year recorded in summer, equivalent to a net temperature rise of 2.82°C), except for the autumn season (cooling without statistical significance). Multidecadally, the 1961-1990 period is marked by a general cooling, especially in autumn (maximum values of-0.07°C/year or over 2°C net cooling). In the 1971-2000 and 1981-2009 periods, a general warming was observed (maximum in summer for both multidecades, when positive rates peaked at 0.09°C/year, or 2.5-3°C net warming), but the warming of the last three decades is the most prominent in terms of spatial average magnitude and trend significance. Upon analysis of the impact of climate warming on agricultural yields (maize) through linear regression, in the 1991-2000 decade, considered as case study, it was found that in 32 % of the total analyzed area there are evident relationships between the two variables (p value \0.05). In this case, a dependency of 33-50 % (40 %, on average) of maize to climate was found, and a sensitivity (loss) ranging between 0.9 and 1.5 t/ha/year (1.2 t/ha/year, on average) for a 1°C temperature rise. At the same time, significant losses (of up to 1.7 t/ha/year) of maize for a 1°C temperature rise were identified in 51 % of the area, but with little p value significance (between 0.05 and 0.1). It is however necessary to analyse the agro-climatic results cautiously, considering that only one decade of climate-agriculture relationship was studied. The results can be useful first and foremost for mitigating the climate change impact on agricultural systems, by prioritizing future adaptation strategies enforced by policy makers.
Carpathian journal of earth and environmental sciences
This paper attempts to analyze the potential relationship between the climatic water deficit of t... more This paper attempts to analyze the potential relationship between the climatic water deficit of the vegetation period of corn (April-September) and its agricultural yield, recorded in the Dobrogea plateau between 1990 and 2003. The data included in this study comprise spatialized climatic water deficit values (mm) (computed as the difference between precipitation and potential evapotranspiration), obtained through interpolation methods based on ten regional weather stations and corn crop yield data (t/ha/year) in 99 territorial administrative units, almost entirely overlapping the analyzed geographical region. The study essentially aims to identify the statistical connection between the independent variable (climatic water deficit) and the dependent one (agricultural yield) over 14 years - to this end, a series of detailed statistical correlations were applied to both variables. The results showed a statistically significant relationship especially in the plateau’s central-southern ...
Nowadays, Southwestern Romania faces a large-scale aridization of the climate, revealed by the ri... more Nowadays, Southwestern Romania faces a large-scale aridization of the climate, revealed by the rise of temperatures and the decline of the amount of precipitations, with negative effects visible, among others, in the desiccation of forest vegetation. The present study means to identify the changes that occurred, quality-wise, in the past two decades (1990-2011) in forest vegetation in Southwestern Romania, and to establish the link between those changes and extant thermal stress in the region, whose particular features are high average annual and seasonal temperatures. In order to capture the evolution in time of climate aridization, a first step consisted in using climate data, the temperature and precipitation parameters from three weather stations; these parameters were analyzed both individually and as aridity indexes (De Martonne and UNEP). In order to quantify the changes in forest vegetation, NDVI indexes were used and analyzed, starting off from Landsat satellite images, acquired at three distinct moments in time, 1990, 2000 and 2011. In order to identify the link between the changes of NDVI index values and regional thermal stress, a yardstick of climate changes, statistical correlations were established between the peak values of average annual temperatures, represented in space, and negative changes in the NDVI index, as revealed by the change-detection analysis. The results obtained indicated there is an obvious (statistically significant) connection between thermal stress and the desiccation (degradation) of forest species in the analyzed area, with false acacia (Robinia Pseudoacacia) the main species to be impacted.
Journal of environmental health science & engineering, Jan 6, 2014
In the past few decades, global climate change has accentuated the intensification of aridization... more In the past few decades, global climate change has accentuated the intensification of aridization in South-Western Romania, with direct and indirect consequences on the quality of forest ecosystems. In addition to qualitative deterioration, the quantitative changes brought about by intensive anthropic deforestation have created the conditions for a decline in the size of forest areas on vast tracts of land. The paper aims to analyze the qualitative and quantitative changes in the forest ecosystems in South-Western Romania, changes due to the synergic context of the global climate changes and the anthropic pressures of the past three decades. In order to capture the evolution of aridization in the study area, specific aridization indexes have been calculated, such as the De Martonne index and the UNEP aridity index. 1990 and 2011 satellite images have been used in order to quantify the qualitative changes. The results obtained indicated that, in the past two decades, the quality of t...
Journal of environmental health science & engineering, Jan 24, 2013
The report released by the Intergovernmental Committee for Climate Change indicates that Romania ... more The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation inde...
The beginning of the atomic age marked the outset of nuclear weapons testing, which is responsibl... more The beginning of the atomic age marked the outset of nuclear weapons testing, which is responsible for the radioactive contamination of a large number of sites worldwide. The paper aims to analyze nuclear weapons tests conducted in the second half of the twentieth century, highlighting the impact of radioactive pollution on the atmospheric, aquatic, and underground environments. Special attention was given to the concentration of main radioactive isotopes which were released, such as 14 C, 137 Cs, and 90 Sr, generally stored in the atmosphere and marine environment. In addition, an attempt was made to trace the spatial delimitation of the most heavily contaminated sites worldwide, and to note the human exposure which has caused a significantly increased incidence of thyroidal cancer locally and regionally. The United States is one of the important examples of assessing the correlation between the increase in the thyroid cancer incidence rate and the continental-scale radioactive contamination with 131 I, a radioactive isotope which was released in large amounts during the nuclear tests carried out in the main test site, Nevada.
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