scholarly journals Future drought episodes over the North of Italy

2021 ◽  
Author(s):  
Alice Baronetti ◽  
Vincent Dubreuil ◽  
Antonello Provenzale ◽  
Simona Fratianni
Keyword(s):  
Climate Models ◽  
Control Period ◽  
Drought Indices ◽  
Drought Severity ◽  
Spatial Gradient ◽  
Drought Duration ◽  
Po River ◽  
Rcp Scenarios ◽  
Duration Magnitude ◽  
Far Future

<p>Droughts are a normal and recurrent climate feature, but they have the greatest consequences, compared to all other natural hazards and can produce severe effects on natural and socioeconomic systems. The northern part of Italy (Po Valley) is historically rich in water resources, and one of the most fertile and productive agricultural areas. Recently drought events increased affecting the hydrological behaviour of the Po river. In fact, since the turn of the century, an increase of the prolongation of the Po river lean period was recorded. In this work near future (2021-2050) and far future (2071-2100) weekly drought events for the Po Plain region, based on 12 daily EURO-CORDEX and MED-CORDEX Regional Climate Models (RCP 4.8 and RCP 8.5) at 12 km<sup>2 </sup>resolution were identified and mapped. First, the model validation was performed, 10 daily precipitation and temperature series (equally distributed in the plain/hill and mountain sector) were extracted and compared with the corresponding quality-controlled and homogenised gridded data obtained from ground stations. The statistical comparison between reference and candidate series for the control period (1971-2000) was performed using the Co.Temp software for temperature and Co.Rain software for precipitation. Then, on the more reliable models, the bias in the annual mean maximum and minimum temperatures between reference and Euro- and Med-CORDEX simulations was estimated. For precipitation, the ratio between reference and simulations was used. Subsequently, daily values were converted to weekly means and the reference evapotranspiration (ETo) was estimated by means of the Hargreaves ETo equation. Severe and extreme drought episodes were detected by mean of two drought indices (SPI and SPEI) calculated at 12-, 24- and 36- month time scales. Trends were analysed, and the main future drought events were characterised, identifying duration, magnitude and extent. For both RCP scenarios, the results have indicated an intensification of droughts in northern Italy for the period 2021-2050, with the Alpine chain being heavily affected by an increase of drought severity and duration. A North-to-South spatial gradient of drought duration was observed for the far future. This study indicates that at least two different triggering factors influence the characteristics of drought events, and it highlights the importance of using multiple drought indicators.</p>

scholarly journals Assessment of the Dissimilarities of EDI and SPI Measures for Drought Determination in South Africa

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 82
Author(s):  
Omolola M. Adisa ◽  
Muthoni Masinde ◽  
Joel O. Botai
Keyword(s):  
South Africa ◽  
South African ◽  
Correlation Coefficient ◽  
Pearson Correlation ◽  
Standardized Precipitation Index ◽  
Drought Monitoring ◽  
Drought Indices ◽  
Drought Severity ◽  
Pearson Correlation Coefficient ◽  
Drought Duration

This study examines the (dis)similarity of two commonly used indices Standardized Precipitation Index (SPI) computed over accumulation periods 1-month, 3-month, 6-month, and 12-month (hereafter SPI-1, SPI-3, SPI-6, and SPI-12, respectively) and Effective Drought Index (EDI). The analysis is based on two drought monitoring indicators (derived from SPI and EDI), namely, the Drought Duration (DD) and Drought Severity (DS) across the 93 South African Weather Service’s delineated rainfall districts over South Africa from 1980 to 2019. In the study, the Pearson correlation coefficient dissimilarity and periodogram dissimilarity estimates were used. The results indicate a positive correlation for the Pearson correlation coefficient dissimilarity and a positive value for periodogram of dissimilarity in both the DD and DS. With the Pearson correlation coefficient dissimilarity, the study demonstrates that the values of the SPI-1/EDI pair and the SPI-3/EDI pair exhibit the highest similar values for DD, while the SPI-6/EDI pair shows the highest similar values for DS. Moreover, dissimilarities are more obvious in SPI-12/EDI pair for DD and DS. When a periodogram of dissimilarity is used, the values of the SPI-1/EDI pair and SPI-6/EDI pair exhibit the highest similar values for DD, while SPI-1/EDI displayed the highest similar values for DS. Overall, the two measures show that the highest similarity is obtained in the SPI-1/EDI pair for DS. The results obtainable in this study contribute towards an in-depth knowledge of deviation between the EDI and SPI values for South Africa, depicting that these two drought indices values are replaceable in some rainfall districts of South Africa for drought monitoring and prediction, and this is a step towards the selection of the appropriate drought indices.

scholarly journals Streamflow droughts in the Iberian Peninsula between 1945 and 2005: spatial and temporal patterns

2012 ◽  
Vol 9 (7) ◽  
pp. 8063-8103 ◽  
Author(s):  
J. Lorenzo-Lacruz ◽  
E. Morán-Tejeda ◽  
S. M. Vicente-Serrano ◽  
J. I. López-Moreno
Keyword(s):  
Iberian Peninsula ◽  
Principal Component ◽  
Threshold Level ◽  
Climatic Conditions ◽  
Drought Severity ◽  
Spatial And Temporal Patterns ◽  
Drought Duration ◽  
Spatial Coverage ◽  
Duration Magnitude ◽  
High Level

Abstract. In this study we analyzed the spatio-temporal variability of streamflow droughts in the Iberian Peninsula from 1945 to 2005. Streamflow series (187) homogeneously distributed across the study area were used to develop a streamflow index (the Standardized Streamflow Index; SSI), which facilitated comparison among regimes and basins, regardless of streamflow magnitudes. A principal component analysis was performed to identify homogeneous hydrological regions having common features, based on the temporal evolution of streamflows. Identification of drought events was carried out using a threshold level approach. We assessed the duration and magnitude of drought episodes and the changes that occurred between two contrasting periods for each hydrological region. The results showed a trend to greater drought severity in the majority of regions. Drought duration, magnitude and spatial coverage was found to depend mainly on the climatic conditions and the water storage strategies in each basin. In some basins these strategies have altered river regimes, and in others created a high level of dependence on storage and water transfer rates.

scholarly journals Forecasting droughts in East Africa

2013 ◽  
Vol 10 (8) ◽  
pp. 10209-10230 ◽  
Author(s):  
E. Mwangi ◽  
F. Wetterhall ◽  
E. Dutra ◽  
F. Di Giuseppe ◽  
F. Pappenberger
Keyword(s):  
East Africa ◽  
Standardized Precipitation Index ◽  
Drought Indices ◽  
Drought Event ◽  
East African ◽  
African Region ◽  
Drought Duration ◽  
Additional Information ◽  
Duration Magnitude ◽  
Rain Season

Abstract. The humanitarian crisis caused by the recent droughts (2008–2009 and 2010–2011) in the East African region have illustrated that the ability to make accurate drought predictions with adequate lead time is essential. The use of dynamical model forecasts and drought indices, such as Standardized Precipitation Index (SPI), promises to lead to a better description of drought duration, magnitude and spatial extent. This study evaluates the use of the European Centre for Medium-Range Weather Forecasts (ECMWF) products in forecasting droughts in East Africa. ECMWF seasonal precipitation shows significant skill for both rain seasons when evaluated against measurements from the available in-situ stations from East Africa. The October–December rain season has higher skill that the March–May season. ECMWF forecasts add value to the statistical forecasts produced during the Greater Horn of Africa Climate Outlook Forums (GHACOF) which is the present operational product. Complementing the raw precipitation forecasts with SPI provides additional information on the spatial extend and intensity of the drought event.

scholarly journals Reference crop evapotranspiration database in Spain (1961–2014)

2019 ◽  
Vol 11 (4) ◽  
pp. 1917-1930 ◽  
Author(s):  
Miquel Tomas-Burguera ◽  
Sergio M. Vicente-Serrano ◽  
Santiago Beguería ◽  
Fergus Reig ◽  
Borja Latorre
Keyword(s):  
Climate Models ◽  
Severity Index ◽  
Important Variable ◽  
Drought Indices ◽  
Drought Severity ◽  
Climate Variables ◽  
Evaporative Demand ◽  
Research Areas ◽  
Climate Studies ◽  
Reference Crop

Abstract. Obtaining climate grids describing distinct variables is important for developing better climate studies. These grids are also useful products for other researchers and end users. The atmospheric evaporative demand (AED) may be measured in terms of the reference evapotranspiration (ETo), a key variable for understanding water and energy terrestrial balances and an important variable in climatology, hydrology and agronomy. Despite its importance, the calculation of ETo is not commonly undertaken, mainly because datasets consisting of a high number of climate variables are required and some of the required variables are not commonly available. To address this problem, a strategy based on the spatial interpolation of climate variables prior to the calculation of ETo using FAO-56 Penman–Monteith equation was followed to obtain an ETo database for continental Spain and the Balearic Islands, covering the 1961–2014 period at a spatial resolution of 1.1 km and at a weekly temporal resolution. In this database, values for the radiative and aerodynamic components as well as the estimated uncertainty related to ETo were also provided. This database is available for download in the Network Common Data Form (netCDF) at https://doi.org/10.20350/digitalCSIC/8615 (Tomas-Burguera et al., 2019). A map visualization tool (http://speto.csic.es, last access: 10 December 2019) is available to help users download the data corresponding to one specific point in comma-separated values (csv) format. A relevant number of research areas could take advantage of this database. For example, (i) studies of the Budyko curve, which relates rainfall data to the evapotranspiration and AED at the watershed scale, (ii) calculations of drought indices using AED data, such as the Standardized Precipitation–Evapotranspiration Index (SPEI) or Palmer Drought Severity Index (PDSI), (iii) agroclimatic studies related to irrigation requirements, (iv) validation of climate models' water and energy balance, and (v) studies of the impacts of climate change in terms of the AED.

scholarly journals Groundwater Drought in the Nitra River Basin - Identification and Classification

2012 ◽  
Vol 60 (3) ◽  
pp. 185-193 ◽  
Author(s):  
Miriam Fendeková ◽  
Marián Fendek
Keyword(s):  
River Basin ◽  
Severity Index ◽  
Base Flow ◽  
Natural Phenomenon ◽  
Drought Indices ◽  
Drought Severity ◽  
Drought Duration ◽  
Drought Assessment ◽  
Groundwater Drought ◽  
Drought Severity Index

Groundwater Drought in the Nitra River Basin - Identification and Classification Drought as a natural phenomenon becomes more often the subject of the research. It is because of the increasing frequency of extreme climatic events also in mild climate conditions. Groundwater drought indices could be derived for different groundwater parameters, among them for base flow, groundwater head stage, spring yield, or groundwater recharge. Base flow drought assessment methods were proposed in the paper. Base flow values were separated from the discharge hydrograms using the new HydroOffice 2010 program package, lately developed by Gregor. The base flow drought severity index was applied, calculated as the value of the base flow drought deficit volume divided by the drought duration. After that, the standardized base flow drought severity index was proposed as the ratio of the base flow drought index and the average long-term annual base flow. Proposed methods were applied in the Nitra River basin. Base flow drought occurrence was characterized also from the seasonality point of view.

scholarly journals Space-time kriging extension of precipitation variability at 12 km spacing from tree-ring chronologies and its implications for drought analysis

2013 ◽  
Vol 10 (4) ◽  
pp. 4301-4335 ◽  
Author(s):  
F. Biondi
Keyword(s):  
Tree Ring ◽  
Great Basin ◽  
Climate Models ◽  
Space Time ◽  
Environmental Data ◽  
Optimal Interpolation ◽  
Drought Duration ◽  
Worst Case ◽  
Individual Site ◽  
Duration Magnitude

Abstract. Understanding and preparing for future hydroclimatic variability greatly benefits from long (i.e., multi-century) records at seasonal to annual time steps that have been gridded at km-scale spatial intervals over a geographic region. Kriging is a geostatistical technique commonly used for optimal interpolation of environmental data, and space-time geostatistical models can improve kriging estimates when long temporal sequences of observations exist at relatively few points on the landscape. Here I present how a network of 22 tree-ring chronologies from single-leaf pinyon (Pinus monophylla) in the central Great Basin of North America was used to extend hydroclimatic records both temporally and spatially. First, the Line of Organic Correlation (LOC) method was used to reconstruct October–May total precipitation anomalies at each tree-ring site, as these ecotonal environments at the lower forest border are typically moisture limited. Individual site reconstructions were then combined using a hierarchical model of spatio-temporal kriging that produced annual anomaly maps on a 12 × 12 km grid during the period in common among all chronologies (1650–1976). Hydro-climatic episodes were numerically identified and modeled using their duration, magnitude, and peak. Spatial patterns were more variable during wet years than during dry years, and the evolution of drought episodes over space and time could be visualized and quantified. The most remarkable episode in the entire reconstruction was the early 1900s pluvial, followed by the late 1800s drought. The 1930s "Dust Bowl" drought was among the top ten hydroclimatic episodes in the past few centuries. These results directly address the needs of water and natural resource managers with respect to planning for "worst case" scenarios of drought duration and magnitude at the watershed level. For instance, it is possible to analyze which geographical areas are more likely to be impacted by severe and sustained droughts at annual or multiannual timescales and at spatial resolutions commonly used by regional climate models.

scholarly journals Uncertainties in runoff projection and hydrological drought assessment over Gharesu basin under CMIP5 RCP scenarios

2020 ◽  
Vol 11 (S1) ◽  
pp. 145-163 ◽  
Author(s):  
S. M. Ashrafi ◽  
H. Gholami ◽  
M. R. Najafi
Keyword(s):  
River Basin ◽  
General Circulation ◽  
General Circulation Models ◽  
Hydrological Drought ◽  
Drought Severity ◽  
Historical Period ◽  
Drought Duration ◽  
Rcp Scenarios ◽  
Drought Assessment ◽  
Drought Characteristics

Abstract Hydrological drought plays an important role in planning and managing water resources systems to meet increasing water demands due to population growth. In this study, the effects of climate change on the hydrological drought characteristics of the Gharasu basin, as one of the major sub-basins of the Karkheh river basin, are investigated. This river basin has experienced severe droughts, and floods, in recent years. The uncertainties in projected drought conditions are characterized based on a suite of 34 general circulation models (GCMs). Based on hydrological simulations over the historical period, 12 GCMs are selected to estimate projected runoff values and the corresponding streamflow drought index (SDI) in the future period. The ‘run theory’ is applied to evaluate the drought characteristics under Representative Concentration Pathways (RCPs) 4.5 and 8.5 emission scenarios. Results show that uncertainties of drought projection under RCP8.5 are higher than under RCP4.5, where among different drought characteristics, the maximum uncertainty is detected for drought severity and maximum drought duration. Moreover, the uncertainty of drought projection in wet periods is greater than that in dry periods.

scholarly journals Drought Trends in the Iberian Peninsula over the Last 112 Years

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
P. Páscoa ◽  
C. M. Gouveia ◽  
A. Russo ◽  
R. M. Trigo
Keyword(s):  
Iberian Peninsula ◽  
Standardized Precipitation Index ◽  
Research Unit ◽  
Climatic Research Unit ◽  
Drought Indices ◽  
Drought Duration ◽  
Mean Intensity ◽  
Duration Magnitude ◽  
Northwestern Region ◽  
The Standardized Precipitation Index

The Iberian Peninsula (IP) is a drought-prone area located in the Mediterranean which presents a significant tendency towards dryness during the last decades, reinforcing the need for a continuous monitoring of drought. The long-term evolution of drought in the IP is analyzed, using the Standardized Precipitation Evaporation Index (SPEI) and the Standardized Precipitation Index (SPI), for the period of 1901–2012 and for three subperiods: 1901–1937, 1938–1974, and 1975–2012. SPI and SPEI were calculated with a 12-month time scale, using data from the Climatic Research Unit (CRU) database. Trends in the drought indices, precipitation, and reference evapotranspiration (ET0) were analysed and series of drought duration, drought magnitude, time between drought events, and mean intensity of the events were computed. SPI and SPEI significant trends show areas with opposite signals in the period 1901–2012, mainly associated with precipitation trends, which are significant and positive in the northwestern region and significant and negative in the southern areas. Additionally, SPEI identified dryer conditions and an increase in the area affected by droughts, which agrees with the increase in ET0. The same spatial differences were identified in the drought duration, magnitude, mean intensity, and time between drought events.

Practical tool for drought characteristics calculation

2021 ◽  
Author(s):  
Mahyar Mottaghi Zadeh ◽  
Maral Habibi
Keyword(s):  
Quantitative Description ◽  
Geographical Location ◽  
Drought Indices ◽  
Drought Severity ◽  
Drought Condition ◽  
Development Environment ◽  
Drought Duration ◽  
Software Application ◽  
Drought Characteristics ◽  
Drought Conditions

<p>There are many ways to identify and monitor drought conditions. Scarcely are tools that calculate drought characteristics, The "SDF Calculator" works to bring monitoring tools to the public so they can assess drought conditions, this tool is used to assess and identify drought and its intensity.</p><p>Drought severity refers to the absolute sum of consecutive SDI values below a given threshold level while drought duration is the number of consecutive months that SDI is below that threshold, and drought frequency is a number of months with drought condition (means SPI < -0.5 or any given threshold that is desire, the threshold of drought index is a value that an index faces to drought condition. In every index, this value can be changed. For example, in many indices, the threshold of drought starts from zero or less zero. In other words, when the value of an index is calculating then all the values located in the drought classes, refer to the severity of the drought.</p><p>Droughts and exceptionally wet periods are regional phenomena, which are considered as major environmental extremes, especially in semiarid regions of the world. The development of severity-duration-frequency (SDF) relationships of droughts and wet periods is important in hydrological and climatic plannings in any country.</p><p>In this study, we aimed to offer a novel software model to be used for a quantitative description of droughts and wet periods to provide an overview of drought intensity and analyzing their severity, frequency, and duration. In addition, we have been able to develop a state-of-the-art bespoke software application, so the users are able to analyze drought based on the regional thresholds. While most of the analysis applications have used programming languages such as R or Python, due to the lack of software libraries in the .NET development environment, we have managed to offer our development environment based on .NET Core and C# programming language. The software application accepts inputs from various file formats or APIs, processes the data, and demonstrates the outcome in different graphs and maps depending on the geographical location of study areas. The outputs are not only can be exported as different formats to be used in big data applications but also might be exposed as web APIs to be used in live applications.</p><p> </p><p> Keywords: Drought characteristics, SDF Calculator, API, Standardized Drought Indices (SDI)</p>

scholarly journals Forecasting droughts in East Africa

2014 ◽  
Vol 18 (2) ◽  
pp. 611-620 ◽  
Author(s):  
E. Mwangi ◽  
F. Wetterhall ◽  
E. Dutra ◽  
F. Di Giuseppe ◽  
F. Pappenberger
Keyword(s):  
East Africa ◽  
Standardized Precipitation Index ◽  
Spatial Extent ◽  
Precipitation Forecast ◽  
Drought Indices ◽  
Drought Event ◽  
Drought Duration ◽  
Consensus Forecasts ◽  
Duration Magnitude ◽  
Rain Season

Abstract. The humanitarian crises caused by the recent droughts (2008–2009 and 2010–2011) in East Africa have illustrated that the ability to make accurate drought forecasts with sufficient lead time is essential. The use of dynamical model precipitation forecasts in combination with drought indices, such as the Standardized Precipitation Index (SPI), can potentially lead to a better description of drought duration, magnitude and spatial extent. This study evaluates the use of the European Centre for Medium-Range Weather Forecasts (ECMWF) products in forecasting droughts in East Africa. ECMWF seasonal precipitation shows significant skill for March–May and October–December rain seasons when evaluated against measurements from the available in situ stations from East Africa. The forecast for October–December rain season has higher skill than for the March–May season. ECMWF forecasts add value to the consensus forecasts produced during the Greater Horn of Africa Climate Outlook Forum (GHACOF), which is the present operational product for precipitation forecast over East Africa. Complementing the original ECMWF precipitation forecasts with SPI provides additional information on the spatial extent and intensity of the drought event.

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