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The questions of scale, limit, and areal extent are central points for any drought assessment effort. Drought indices, such as the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), are assisting to demarcate drought characteristics and spatial extent. The current approach utilizes the E-OBS g...
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Drought is one of the natural hazards that have negatively affected the agricultural sector worldwide. The aims of this study were to track drought characteristics (duration (DD), severity (DS), and frequency (DF)) in South Africa between 2002 and 2021 and to evaluate its impact on wheat production. Climate data were collected from the South Africa...
South Africa is susceptible to droughts. However, there is little documentation on drought occurrence in South Africa at national level and its various administrative boundaries. The study aimed to profile the hydrological drought in ORTDM from 1998–2018; computing their frequency, severity and intensity so as to show areas of high vulnerability. D...
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In Poland, recent summer droughts have had devastating environmental, social, and economic consequences, but the trend of growing season dryness remains unclear. This study focuses on the soil moisture and evaporative stress conditions, analyzed in a multiyear period between 1981 and 2019. Country scale trends in growing season drought severities a...
Citations
... Numerous studies have examined how drought changes (Tsakiris et al., 2008;Azimi et al., 2020;Oikonomou et al., 2020;Tatli et al. 2020;Topcu & Seckin, 2021;Motavali Bashi Naeini et al. 2021;Kamali & Asghari, 2022;Chisadza et al., 2023;Achite et al., 2023). This studies considered different drought indices and discussed the ability of each. ...
Identifying the changes and effects of drought (as a natural creeping phenomenon) as accurately as possible is very effective and essential in managing how to deal with this phenomenon. To study drought in more detail, the main objective of this research is to consider the stability and changes of drought in different moving periods (MPs). These investigations were performed for various seasonal and annual time scales using rainfall values and reconnaissance drought index (RDI). The results showed sinusoidal changes in trend correlation coefficients (TCCs) for the 10-year MP, in which the wave amplitude became shorter and wavelength became longer as the MP lengthened. In recent MPs, the coefficient values of the trend were increasing. The RDI analysis showed that, in addition to the mentioned changes, the trend of autumn time scale changes in the 15- and 20-year MPs, especially after MP7, was the opposite of the change trend in other time scales, especially the winter time scale. According to the results, the values of P(N/N) were greater than the values of P(N/P), which showed the stability of the decreasing trend of rainfall and RDI changes in different MPs, especially at 10 years.
... Evidence of all this was observed in 2011, a year of particularly intense agricultural drought in the German regions (Figure 4), causing an average yield reduction of more than 9% in cereals (Table 4). This result is consistent with that of [142], which classified the 2011 drought in the EU as having the largest spatial extent on record. In the same context, [115] studied droughts using meteorological indices for southwestern Germany and classified 2011 as one of the most extreme years with precipitation shortages accompanied by high temperatures. ...
Given the growing interest in drought impacts on crops, this work studied the impact of agricultural drought on wheat and barley during the period 2001–2020. The study was carried out in the Spanish regions of Castilla y León and Castilla–La Mancha, with approximate areas of 94,000 km2 and 79,000 km2, respectively, and in the German regions of Nordrhein-Westfalen, Niedersachsen and Bayern, with approximate areas of 34,000 km2, 48,000 km2 and 71,000 km2, respectively. These are the main cereal-growing regions of Spain and Germany. Soil moisture (SM) in the root zone was extracted from the LISFLOOD model database, and SM anomalies were used as the agricultural drought index. Gross primary productivity (GPP) and leaf area index (LAI) variables were obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS), and the month in which SM is most influential on these crop state variables was identified. Crop yields in Spain and Germany were obtained from the Spanish Ministry of Agriculture, Fisheries and Food and the German Federal Statistical Office, respectively. Agricultural drought years and their impact on cereal yields were determined on a regional scale using three approaches based on the critical month with different time periods. These approaches were the use of the critical month and the two (before or after) and the three months (before and after) around the critical month. Two different analyses were used to identify the critical month, depending on the different environmental conditions in each country. These two approaches consisted of a monthly correlation analysis between SM anomalies and cereal yield in Spain and a monthly trend analysis of SM anomalies in Germany. The results showed a dependence of crop variables on SM in spring months in both countries and in summer months in Germany. Differences were found depending on the environmental conditions. A considerable reduction in cereal yields was obtained in Spain which exceeded 30%. Similarly, a worrying sign was observed in Germany, with a positive agricultural drought trend and a yield reduction of almost 5% in cereal crops. In view of future forecasts of the negative impact of climate change on global food production, this study provides valuable information for water and agricultural management under climate change scenarios. Both in regions that are already threatened and in those that until recently were not affected, it is necessary to study adaptation measures to avoid aggravating the impact of agricultural drought on crops, which could improve water productivity and future food security.
... Beavers are semi-aquatic rodents that need water throughout the year; feeding and other activity mostly occurs within 20 m of the water edge (Gaywood, 2018). Therefore, severe droughts in warm months as those occurring in southern Europe are major limiting factors (Zavyalov et al., 2015;Oikonomou et al., 2020;Sutanto et al., 2020;Serva, Biondi, & Iannella, 2023). Similarly, in Italy, suitability was low in areas with cold climates (e.g. the Alps) or with warm and dry Mediterranean climates (e.g. ...
Reintroduction and rewilding initiatives are key strategies to reverse human impacts on ecosystems and re-establish natural processes. However, rewilding may involve complex management scenarios, because many expanding species can have economic impacts and cause human-wildlife conflicts. Conflicts can be particularly challenging when carnivores, large herbivores and ecosystem engineers are involved. The Eurasian beaver (Castor fiber) is a key ecosystem engineer that was once present in a large part of the Palearctic, but in Medieval times underwent a severe decline due to the joint effects of habitat loss and hunting. Subsequent legal protection and reintroductions triggered the recovery of the species through most of its original range. Eurasian beavers recently started the recolonization of Italy, because of the joint effects of natural dispersal (from Austria to northern Italy) and illegal reintroductions (central Italy). The lack of data on the most likely coloniza-tion routes hampers appropriate management of this species. Here, we identified the areas where beaver populations are most likely to arrive in the near future within Europe, with a specific focus on Italy. First, we developed spatially cross-validated species distribution models to identify the areas with the highest suitabil-ity for the Eurasian beaver in Europe. Second, we used connectivity modelling to assess the possible expansion routes of this species in Italy. Large areas of Europe are suitable for the beaver and may soon be colonized. The connectivity model showed a high potential for expansion from central Italy to surrounding areas, while the high isolation of northern Italy populations suggests a slower expansion. Our results can help environmental managers to understand where to focus both the future monitoring of beaver populations and actions aimed at preventing and mitigating possible human-wildlife conflicts that could arise from the expansion of an environmental engineer such as the beaver.
... Among the other authors who focused their studies on SPEI in the conditions of European climate, [25] (Serbia) and [26] (Europe) decided to use GEV in their work, while [27] (Czech Republic); [17] (Europe); [28] (Europe); [29] (six European sites located in midlatitudes); and [30] (Europe) followed the Log-logistic distribution. ...
In the conditions of rising air temperature and changing precipitation regimes in Central Europe and Slovakia over the last two decades, it is necessary to analyse drought, develop high-quality tools for drought detection, and understand its reactions to the emerging drought situation. One of the frequently used meteorological drought indices is the Standardized Precipitation and Evapotranspiration Index (SPEI). Several parameters can be modified in different steps of the calculation process of SPEI. In the article, we analyse the influence of selected adjustable parameters on the index results. Our research has shown that the choice of a statistical distribution (Log-logistic, Pearson III, or Generalized Extreme Value) for fitting water balance can affect the feasibility of calculating distribution parameters (and thus the index) from the provided input data, as well as lead to either underestimation or overestimation of the index. The normality test of SPEI can be used as a tool for the detection and elimination of highly skewed indices and cases when the indices were not well determined by the distribution function. This study demonstrated improved results when using the GEV distribution, despite the common use of the Log-logistic distribution. With the Pearson III distribution, unusually high or low SPEI values (|SPEI| > 6) were detected.
... Characterization of drought is necessary for the planning of various activities in the economy, industry, or water sector in general. Drought and spatial distribution of drought events in Europe were characterized by Oikonomou et al. (2020). ...
The precipitation-based indices such as the standardized precipitation index (SPI), the standardized anomaly index (SAI), the rainfall anomaly index (RAI), the percent of normal precipitation (PNP), the China Z index (CZI), and the modified China Z index (MCZI) were compared using monthly precipitation data from 28 synoptic stations in Serbia for the period 1946–2019. The MCZI and CZI showed the lowest similarity to the SPI index that was selected as a reference drought index. According to the findings of the present study, the RAI index was proposed as an index that has the most similar performance to the SPI index. Based on the spatial distribution of the RAI values for the year 2000, the whole region except the western part of Serbia can be classified as extremely dry.
... Given the climate expected in the near future, a more frequent summer drought will occur in Europe [2,40], one of the major yield-limiting climate factors [41]. Drought is an abiotic factor that causes significant yield losses, especially in rain-fed agriculture. ...
To investigate the different responses of crops to drought stress under field conditions of Central European Climate for selected crop rotations, a field experiment was conducted at a test site in the Czech Republic from 2014 to 2021. Depending on the crop, rainout shelters were placed in late spring and early summer to study the effects of drought in the final stages of crop development. Due to these rainout shelters and the associated lower water availability for the crops during the summer, a reduction in leaf area index, biomass and yield was observed. For example, a yield decrease of more than 30% was observed for spring barley, winter rape and winter wheat compared to conditions without rainout shelters. The reduction was 25% and 18% for winter rye and silage maize, respectively, under rainout shelters. Soil moisture played a significant role in yield, where a predictive model based on monthly soil moisture explained up to 79% (winter rape) of the yield variance.
... An SPI3 selection depicts eastern Europe and increasing tendencies over southern and eastern Europe, while central Europe and some parts of eastern Europe represent the transition zone. On the contrary, using monthly steps above 6 months depicts more drought events in central and northern Europe [26,[51][52][53][54][55]. ...
... Using this drought index with 6-and 12-month scales may demonstrate irregular water resources and extremely low-level reservoir storage (hydrological droughts) [7,26,40,56,57]. For every climatic zone in Europe, SPI values of time scales of 6 months or above are more suitable for drought characterization than time scales of 3 months or below. ...
The ever-increasing need for water, the alteration in the climate, and its observed changes over recent years have triggered a lot of research studies associated with the phenomenon of drought. Within the wider geographical region of the Mediterranean, the relevant scientific subject seems to be of great interest, since it is undoubtedly related to a number of severe socio-economic consequences. This present effort focuses on the evolution of this particular phenomenon over time, within the borders of nine different countries in the Eastern Mediterranean (Athens, Greece—Europe; Constantinople, Turkey—Asia; Nicosia, Cyprus—Europe; Jerusalem, Israel—Asia; Amman, Jordan—Asia; Damascus, Syria—Asia; Beirut, Lebanon—Asia; Cairo, Egypt—Africa; and Tripoli Libya—Africa). By applying the Standard Precipitation Index (SPI), examining precipitation data at the month level (January 1901 to December 2020), and utilizing the Inverse Distance Weighted (IDW) method, the spatio–temporal variability of drought events in the Eastern Mediterranean area was studied. In Jerusalem, long-term droughts presented a higher than usual volume, in accordance with applying the 12- and 24-month SPI, starting from the mid-20th century. Similarly, the region of Damascus presented a similar pattern to those in Beirut, Amman, and Jerusalem. An upward trend in the frequency of extreme drought events was observed for the last thirty years. The same trend seems to be true in terms of the duration of dry periods. Drought events have also been observed in the central, southern, and eastern regions of Turkey. A downward trend was observed in Cairo based on a trend analysis of its monthly precipitation.
... In Euro-Mediterranean (climate change "hotspot" basin), increasing temperature trend and decreasing rainy days and precipitation deficit cause drought conditions with increasing frequency. Therefore, characterization of drought patterns in this basin are studied in detail by using index values of Palmer Drought Severity Index (PDSI; Briffa et al., 1994;Mika et al., 2005;Trnka et al., 2016;Vasiliades & Loukas, 2009;Vicente-Serrano et al., 2015), Standardized Precipitation Index (SPI; Br azdil et al., 2016;Oikonomou et al., 2020;Trnka et al., 2016;Vicente-Serrano et al., 2021;Vido & Nalevankov a, 2020), Standardized Precipitation Evapotranspiration Index (SPEI; Li et al., 2015;Manzano et al., 2019;Vicente-Serrano et al., 2010). For Europe, the impacts of drought on agriculture (Gil et al., 2011;Hlavinka et al., 2009;Jayanthi et al., 2014;Potop, 2011;Quijano et al., 2015), surface water resources (Vicente-Serrano et al., 2014), forestry (Muukkonen et al., 2015;Vicente-Serrano et al., 2012), human mortality (Dilley et al., 2005) and energy and industry (Stagge et al., 2015) are generally investigated in detail. ...
As a natural disaster, drought affects many sectors such as agriculture and hydrology, as well as having an effect on air quality. In terms of air pollution, drought can reduce wet scavenging of pollutants and change their chemical production/loss and lifetime. This study investigates the relationship between drought events and air pollutants in Turkey. As a drought indicator, the Standardized Precipitation‐Evapotranspiration Index (SPEI)‐1 monthly values for dry (SPEI < −0.99), normal (−0.99 < SPEI < 0.99) and wet (SPEI < 0.99) conditions were used to investigate the changes in PM 10 , PM 2.5 , O 3 concentration levels. Monthly mean PM 10 values of 80 stations for the period 2010–2018, PM 2.5 and O 3 values of 10 and 12 stations, respectively, were used for the analysis throughout the 2014–2018 period. According to the results, while frequency occurrence of normal conditions decreased in the last period (2010–2018) when compared to the first (1901–2009), drought conditions have significantly increased in each region of Turkey in the last decade. Highest increase in drought events occurred in the inner/southern parts of Turkey. In dry events, while PM 10 levels of the stations show above‐normal values, highest regional increase in PM 10 was found in the Central Anatolia (CAR), Mediterranean (MeR), Aegean (AR) and Marmara (MR) regions of the country. In fall, high daily temperatures and cloudless days in CAR and MeR regions are seen under deep surface low over continental Europe and surface high over Caspian Sea, which result in severe dryness events and associated high PM 10 values in the air quality stations. On the other hand, as a consequence of the expanding Asiatic monsoon low to the eastern part of Turkey, significant amount of moisture is transferred from the Eastern Mediterranean Sea surface to the CAR and MeR regions by southerly flows (wetness SPEI conditions in fall) and cause to appear below‐normal PM 10 values in the southern stations.
... There are studies that suggest an increasing trend (e.g., Dai, 2011Dai, , 2013Sheffield et al., 2012;Trnka et al., 2016), a decreasing trend (e.g., Spinoni et al., 2014) and no trend (e.g., Spinoni et al., 2019;Oikonomou et al., 2020;Vicente-Serrano et al., 2021) for droughts for the past decades in the central European region. The discrepancies in the findings are due to the complex characteristics and several different ways of defining (Mishra and Singh, 2010;D. ...
Droughts are among the most relevant natural disasters related to climate change. We evaluated different regional climate model outputs and their ability to reproduce observed drought indices in Germany and its near surroundings between 1980–2009. Both outputs of an ensemble of six EURO-CORDEX models of 12.5 km grid resolution and outputs from a high-resolution (5 km) Weather Research and Forecasting (WRF) run were employed. The latter model was especially tailored for the study region regarding the physics configuration. We investigated drought-related variables and derived the 3-month standardized precipitation evapotranspiration index (SPEI-3) to account for meteorological droughts. Based on that, we analyzed correlations, the 2003 event, trends and drought characteristics (frequency, duration and severity) and compared the results to E-OBS. Methods used include Taylor diagrams, the Mann–Kendall trend test and the spatial efficiency (SPAEF) metric to account for spatial agreement of patterns. Averaged over the domain, meteorological droughts were found to occur approximately 16 times in the study period with an average duration of 3.1 months and average severity of 1.47 SPEI units. WRF's resolution and setup were shown to be less important for the reproduction of the single drought event and overall drought characteristics. Depending on the specific goals of drought analyses, computation resources could therefore be saved, since a coarser resolution can provide similar results. Benefits of WRF were found in the correlation analysis. The greatest benefits were identified in the trend analysis: only WRF was able to reproduce the observed negative SPEI trends to a fairly high spatial accuracy, while the other regional climate models (RCMs) completely failed in this regard. This was mainly due to the WRF model settings, highlighting the importance of appropriate model configuration tailored to the target region. Our findings are especially relevant in the context of climate change studies, where the appropriate reproduction of trends is of high importance.
... Flash droughts (FDs) are a special form of drought. In contrast to the descriptions of classical droughts (de Araújo & Bronstert 2015;Oikonomou et al. 2020), FDs are characterised by rapid onset and relatively short durations (Otkin et al. 2018;Lisonbee et al. 2021). They are associated with severe and immediate soil moisture depletions, resulting in plant water stress and mortality (Ford & Labosier 2017;Liang & Yuan 2021;Osman et al. 2021). ...
Many definitions and delineation methods exist for identifying flash droughts (FDs), which are events of rapid and unusual large depletion of root-zone soil moisture, in comparison to average moisture conditions, due to climatic compound conditions over a short period of several weeks. Six FD identification methods were compared to analyse their functioning using data from several experimental cropland sites across Central Europe. Co- and misidentification of the FD time series were assessed using confusion and synchronicity metrics on a local scale. Even though a large degree of synchronicity of individual FD events was observed, some divergence in drought periods was detected, which was related to four intrinsic differences in the underlying FD definitions: (1) type of critical variable; (2) velocity of drought intensification; (3) pre-set threshold values for final depletion and/or (4) minimum length of the duration of FDs. To balance the strengths and weaknesses of those methods that are not based on soil moisture, we suggest using an ensemble approach for event identification, which is validated in this study for the temperate central European region. In doing so, the current unclearly defined sub-types of FDs can be detected, regardless of the different combinations of compound drivers and differences in intensification dynamics. All methods were implemented in an R package and are available as a Shiny app for the public.
HIGHLIGHTS
The multiple methods proposed to identify flash droughts (FDs) show substantial disagreement.;
Soil moisture is the key variable to identify FDs in croplands; however, such data are scarce, and a method based on proxy variables is necessary.;
A multi-index or multi-method should be favoured in identifying FDs, as a single proxy (to soil moisture) may cause significant misidentification.;
