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Urban Heat Island (UHI) and Heat Waves (HWs) are very important research topics as they have a strong impact on society and their synergies are not enough understood. Urbanisation and global warming are dynamic processes that amplify the UHI intensity and the HWs, as well as their synergies. In this context, it is not a surprise to see that the number of publications tackling the linkages between UHI and HWs has constantly increased in the last decades. The development of new instruments and technologies allowed for consistent improvements in the temporal and spatial resolution of the data that boosted both the monitoring and analysis of the UHI-HW. The use of satellite remote sensing was very limited at the beginning of the analysed period and has become common practice in the last decade. Last, but not least, the interdisciplinary approaches, including physical, social, and economic aspects are more frequent and support the integrated development of the urban areas. Such changes are captured in this review including more than 400 titles, covering the period 1991–2022, aiming to foster further research on emergent climate change risks at urban scales and contextualise the future urban planning. This review provides a comprehensive, accessible and structured overview of the UHI-HW topic as a support for a better understanding of the gaps to be addressed by future research.

Land degradation (LD) and desertification (DS) are a sensitive global issue including southern and south-eastern Europe, which is severely affected by climate change. In this study, a state-of-the-art approach for assessing the intensity of LD and DS processes using remote-sensing-derived indicators within a GIS environment was proposed. The analysis was carried out using the Principal Component Analysis based on integrating the significant trends of relevant biophysical parameters in Romania. The methodology was tested and validated at the national level in Romania. In total, 7.76% of the area was identified as LD and 60.8% of the total area tended to improve, and 31.44% was stable. Most of the regions with LD overlapped with the dryland areas, while improvement areas were identified outside of the drylands. In forested areas from high altitudes, a tendency to improve the condition of vegetation was observed, and most of the surfaces being protected were natural areas that have benefited from proper management. All these results can be used to adapt management practices to avoid, reduce, or restore the LD. The proposed model was based on globally available remote sensing datasets, with a high frequency of data acquisition and collection history that allows for the statistical analyses of changes on a global scale.

Assessing drought severity and its impact on vegetation within Oltenia Plain using NDVI from MODIS (2000-2010). Remote sensing is often used for detecting seasonal vegetation changes, treating a phenomenon both from a spatial and temporal perspective. Regional assessment of the drought has a huge importance in future studies and measures taken in order to diminish its negative effects in the agricultural sector. Considering this fact as a premise, the primary objective of our study aims at observing the impact on the vegetation of the wellknown and, probably, the most severe meteorological risk in Oltenia Plain, the drought, using the NDVI analysis and several drought indexes and correlations. At the same time, one of our goals was to see the characteristic periods of the drought by consulting the effects it has over the vegetation. Although a lot of work has been devoted to examining the drought on a temporal and spatial scale, the results were conclusive, showing a direct relation between the values of the rainfall and the phenological state of the vegetation. Our interest was accomplished via a multi-indices assessment of the drought impact, according to which, the binome vegetation – humidity proved to be the best way to estimate the drought periods in Oltenia Plain, as well as drought exposure and vulnerability.

Abstract Globally, ecosystems are constantly degrading as a result of pressures derived from human activities and climate change. For working towards the restoration of the natural balance, it is necessary to evaluate the deviations induced in the ecosystems, to identify where the changes took place, to know what is their amplitude and to decide where it is possible to get involved. Many aquatic ecosystems are depreciated and their restoration is often difficult. Development of appropriate assessment methodologies will improve the decision-making process in public policies for environmental protection and conservation of biodiversity. This study presents an assessment of the degradation level of lentic ecosystems in Romania, performed through a multi-criteria analysis. An extension of the WRASTIC index (Wastewater-Recreational-Agricultural-Size-Transportations-Indutrial-Cover) was generated, namely WRASTIC-HI. The new index was obtained by including values derived from the Potential Pollutant Load index. The analysis showed that 13% of the evaluated lakes are natural, 56.5% are semi-degraded and 30.5% are degraded. The proposed methodology allows to determine the spatial distribution of the degradation sources and to calculate the corresponding indicators. The results obtained provide a useful tool for diagnostic step that can be used as a cornerstone to further identification of environmental conflicts and proposals for improvement of the ecological status of the lentic ecosystems.

This paper will assess the sensitivity of soil moisture anomaly (SMA) obtained from the Soil water index (SWI) product Metop ASCAT, to identify drought in Romania. The SWI data were converted from relative values (%) to absolute values (m3 m−3) using the soil porosity method. The conversion results (SM) were validated using soil moisture in situ measurements from ISMN at 5 cm depths (2015–2020). The SMA was computed based on a 10 day SWI product, between 2007 and 2020. The analysis was performed for the depths of 5 cm (near surface), 40 cm (sub surface), and 100 cm (root zone). The standardized precipitation index (SPI), land surface temperature anomaly (LST anomaly), and normalized difference vegetation index anomaly (NDVI anomaly) were computed in order to compare the extent and intensity of drought events. The best correlations between SM and in situ measurements are for the stations located in the Getic Plateau (Bacles (r = 0.797) and Slatina (r = 0.672)), in the Western Plain (Oradea (r = 0.693)), and in the Moldavian Plateau (Iasi (r = 0.608)). The RMSE were between 0.05 and 0.184. Furthermore, the correlations between the SMA and SPI, the LST anomaly, and the NDVI anomaly were significantly registered in the second half of the warm season (July–September). Due to the predominantly agricultural use of the land, the results can be useful for the management of water resources and irrigation in regions frequently affected by drought.

The aim of this study is to analyze the performance of the Drought Severity Index (DSI) in Romania and its validation based on other data sources (meteorological data, soil moisture content (SMC), agricultural production). Also, it is to assess the drought based on a multi-temporal analysis and trends of the DSI obtained from Terra MODIS satellite images. DSI is a standardized product based on evapotranspiration (ET) and the Normalized Difference Vegetation Index (NDVI), highlighting the differences over a certain period of time compared to the average. The study areas are located in Romania: three important agricultural lands (Oltenia Plain, Baragan Plain and Banat Plain), which have different environmental characteristics. MODIS products have been used over a period of 19 years (2001–2019) during the vegetation season of the agricultural crops (April–September). The results point out that those agricultural areas from the Baragan Plain and Oltenia Plain were more affected by drought than those from Banat Plain, especially in the years 2002, 2007 and 2012. Also, the drought intensity and the agricultural surfaces affected by drought decreased in the first part of the vegetation season (March–May) and increased in the last part (August–September) in all three study areas analyzed. All these results are confirmed by those of the Standardized Precipitation Evapotranspiration Index (SPEI) and Soil Moisture Anomaly (SMA) indices.

Analysis of drought phenomenon within Oltenia Plain, Romania (1961-2010). Oltenia Plain, located in the south-western part of the Romanian Plain, is characterized by a moderate pluviometric regime (compared to the pluviometric patterns of plain areas from Romania) and, thus, each negative deviation generates certain complex phenomena, such as drought, that trigger perturbations of the natural environment and economic activities. Thus, determining the annual, seasonal and monthly negative deviations of precipitation at local scale is extremely important in order to establish accurate trends of drought phenomenon. We used 50-year time series (1961-2010) for six meteorological stations. The Standardized Precipitation Anomaly (SPA) and Weighted Anomaly of Standardized Precipitation (WASP) indicate a high predominance of normal years (>70%), both at annual and monthly levels. However, there clearly resulted a deterioration of the rainfall regime in the past three decades – normal years, but negative deviations in 80% of the cases; the driest years in the last five decades (1992, 1993, 2000, 2008); the wettest years (1999 and 2005). Linear regression emphasizes an obvious negative trend of the SPA values for the western and eastern parts of the plain (D.T. Severin, Caracal) and a positive trend for the northern extremity (Craiova); the rest of the region displays a slightly negative trend. At monthly level, the most exposed season is summer, even if drought affected the region in all the months of the year. For the last decade, the impact of drought was also assessed based on satellite images SPOT- VEGETATION and TERRA/MODIS. We used the products NDVI (Normalized Difference Vegetation Index), 10-day synthesis and 1 km spatial resolution and LAI (Leaf Area Index) 8-day synthesis, 1 km spatial resolution, data supplied by French Spatial Agency and NASA. The analysis of these products allowed us to emphasize a spatial and temporal differentiation of the density of vegetation within Oltenia, mainly induced by rainfall deficit and variability.

Análisis de los déficit de precipitación y su impacto sobre la vegetación de Oltenia Illano usando imágenes de satélite durante el período 2000-2009. Este investigación pretende evaluar el déficit de precipitaciones en temporada de verano y su impacto sobre la vegetación. Disminución de las precipitaciones en comparación con el valor medio representa el primer firme que precede el sequía. El análisis de los resultados de el Índice de Precipitación Estandarizado calculado por tres meses (SPI-3) y el mes (SPI-1), reveló que durante 2000-2009 en la Oltenia Illano tuvimos 5-6 años deficientes de precipitation de los cuales 2 años fueron calificados como los años secos y muy secos. Este déficit se observa en el análisis de satélite productos, NDVI y LAI obtenido por procesamiento de imágenes Spot-Vegetation y MODIS en la tercera década de cada mes de verano. Las imágenes de satélite revelan las diferencias temporales y espaciales de esta parametro meteorologico y el impacto que tiene en la vegetación de la llanura de Oltenia.