scholarly journals Analysis of Temporal-Spatial Variation Characteristics of Drought: A Case Study from Xinjiang, China

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 741 ◽  
Author(s):  
Qiang An ◽  
Huaxiang He ◽  
Juanjuan Gao ◽  
Qianwen Nie ◽  
Yingjie Cui ◽  
...  
Keyword(s):  
Comprehensive Evaluation ◽  
Standardized Precipitation Index ◽  
Winter Season ◽  
Animal Husbandry ◽  
Scientific Basis ◽  
Drought Severity ◽  
Monthly Precipitation ◽  
North West ◽  
The North ◽  
The Standardized Precipitation Index

It is of great significance to study the characteristics and change trends of drought in Xinjiang to provide a basis for implementing local strategies. Based on monthly precipitation and temperature data from 95 meteorological stations in Xinjiang, from 1960 to 2018, the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated, and the characteristics and trends of drought in Xinjiang were analysed, in details. Furthermore, a comprehensive evaluation index, i.e., Regional Drought Severity (RDS), was proposed to analyse the effects of duration of the drought and the extent of the drought affected area. The results from our study suggested: (1) In consideration of global warming, droughts in Xinjiang have intensified during the past 59 years, and the frequency and range of droughts have increased significantly; (2) During the plant growing season, spring, summer, and autumn, a drying trend was observed, while, a wetting trend was identified for winter season; (3) The drought-prone months shifted from January and December to March-November in the 1970s, and April was identified as a month with the highest frequency of droughts; (4) The meteorological change occurred a period near 1997. It can be speculated that the intensified droughts can be triggered by the excessive temperature rise, through comparing the changes in SPEI and the Standardized Precipitation Index (SPI), before and after the meteorological change; (5) After the meteorological change, the frequency of droughts with different levels had significantly increased, in addition, the drought-prone areas shifted from the north-west to the south-east. The results from this research provide important support for drought management in Xinjiang, also offer scientific basis for the formulation of relevant policies on agricultural and animal husbandry production.

scholarly journals Comparison of Some Drought Indices in Iraq

2020 ◽  
Vol 30 (4) ◽  
pp. 1
Author(s):  
Usama Sameer Nedham ◽  
Ahmed Sami Hassan
Keyword(s):  
Standardized Precipitation Index ◽  
Precipitation Anomaly ◽  
Drought Indices ◽  
Drought Severity ◽  
Monthly Precipitation ◽  
Wet Season ◽  
Future Period ◽  
Intergovernmental Panel ◽  
The North ◽  
The Standardized Precipitation Index

Drought in Iraq was assessed using three drought indices for two different time periods, past period from 1970 to 2015, and future period from 2016 to 2050 for 4 stations in Iraq. These indices named: the Standardized Precipitation Index (SPI), Percentage of Precipitation Anomaly (PPA), and Z-Score Index (ZSI). The main sources of data were the monthly rainfall archive from Iraqi Meteorological Organization and Seismology (IMOS) for past period, and projection monthly precipitation data from Representative Concentration Pathway scenario (RCP4.5) for Fifth Assessment Report (AR5) affiliate to the Intergovernmental Panel on Climate Change (IPCC) for future period. The results shown good correlation of among 3 indices, with different rank of them, were lowest rank was 0.85. The three indices refer to were good evaluate the drought severity of Iraq. Found too the best index was PPA during past period, and the significant index was ZSI for the future period. The North of Iraq (Mosul Station) was the least vulnerable to drought from the analysis of the results of the three indices for the last period, where the number of dry seasons were 12 on the basis of the PPA classification. South of Iraq (Basra station) has the highest number of wet season on the PPA rating were (15) season.

scholarly journals Drought monitoring and prediction using SPI, SPEI, and random forest model in various climates of Iran

2021 ◽  
Author(s):  
Morteza Lotfirad ◽  
Hassan Esmaeili-Gisavandani ◽  
Arash Adib
Keyword(s):  
Random Forest ◽  
Correlation Coefficient ◽  
Potential Evapotranspiration ◽  
Standardized Precipitation Index ◽  
Monthly Precipitation ◽  
Model Combination ◽  
The North ◽  
Drought Prediction ◽  
Lag Times ◽  
The Standardized Precipitation Index

Abstract The aim of this study is to select the best model (combination of different lag times) for predicting the standardized precipitation index (SPI) and the standardized precipitation and evapotranspiration index (SPEI) in next time. Monthly precipitation and temperature data from 1960 to 2019 were used. In temperate climates, such as the north of Iran, the correlation coefficient of SPI and SPEI was 0.94, 0.95, and 0.81 at the time scales of 3, 12, and 48 months, respectively. Besides, this correlation coefficient was 0.47, 0.35, and 0.44 in arid and hot climates, such as the southwest of Iran because potential evapotranspiration (PET) depends on temperature more than rainfall. Drought was predicted using the random forest (RF) model and applying 1–12 months lag times for next time. By increasing of time scale, the prediction accuracy of SPI and SPEI will improve. The ability of SPEI is more than SPI for drought prediction, because the overall accuracy (OA) of prediction will increase, and the errors (i.e., overestimate (OE) and underestimate (UE)) will reduce. It is recommended for future studies (1) using wavelet analysis for improving accuracy of predictions and (2) using the Penman–Monteith method if ground-based data are available.

scholarly journals Spatiotemporal Analysis of Droughts over Different Climate Regions using Hybrid Clustering Method

2021 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Roghayeh Ghasempour ◽  
Vahid Nourani
Keyword(s):  
Standardized Precipitation Index ◽  
Spatiotemporal Analysis ◽  
Mitigation Strategies ◽  
Drought Severity ◽  
Spatiotemporal Pattern ◽  
Discrete Wavelet ◽  
Drought Duration ◽  
Time Frequency ◽  
The North ◽  
The Standardized Precipitation Index

Abstract Drought spatiotemporal variations assessment is an efficient method for implementing drought mitigation strategies and reducing its negative impacts. In this study, the spatiotemporal pattern of short to long-term droughts was assessed for an area with different climates. 31 stations located in Iran were considered and the Standardized Precipitation Index (SPI) series with timescales of 3, 6, and 12 months were calculated during the 1951-2016 period. A hybrid methodology namely Maximal Overlap Discrete Wavelet Transform (MODWT) was applied to obtain the SPIs time-frequency properties and multiscale zoning was done via K-means clustering approach. The energy amounts of decomposed subseries via the MODWT were used as inputs for K-means approach. Also, the statistics in drought features (i.e. drought duration, severity, and peak) were assessed and the results showed that shorter term droughts (i.e. SPI-3 and -6) were more frequent and severe in the north parts where the lowest values of drought duration were obtained. It was observed that the regions with more droughts frequency had the highest energy values. For shorter term droughts a direct relationship was obtained between the energy values and mean SPI, drought severity, and drought peak, whereas an inverse relationship was obtained for longer term drought. It was found that with increasing the degree of SPI, the similarity of the stations of each cluster increased too and the homogeneity of stations for the SPI-12 was slightly higher than the SPI-3 and -6.

scholarly journals Variabilidad espacio-temporal de las sequías en la cuenca Pacífico Norte de México (1961-2010)

2016 ◽  
Vol 42 (1) ◽  
pp. 185 ◽  
Author(s):  
L. Serrano-Barrios ◽  
S. M. Vicente-Serrano ◽  
H. Flores-Magdaleno ◽  
L. Tijerina-Chávez ◽  
D. Vázquez-Soto
Keyword(s):  
Standardized Precipitation Index ◽  
Maximum Temperature ◽  
Drought Indices ◽  
Drought Severity ◽  
Evaporative Demand ◽  
The North ◽  
Weather Stations ◽  
Potential Impact ◽  
Spatio Temporal ◽  
The Standardized Precipitation Index

This article analyses the spatio-temporal variability of droughts in the North Pacific Basin of México between 1961 and 2010, using two drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). We used data from 48 weather stations with available data of precipitation and monthly minimum and maximum temperature. In 22 of the weather stations, time series of Piché evaporation were also available. The reference evapotranspiration, necessary to obtain the SPEI, was calculated by means of the Hargreaves equation. Results show that major droughts occurred in the 1980s and 2000s, although there is a noticeable spatial variability across the region. Finally, the potential impact of the atmospheric evaporative demand on drought severity observed by the different drought indices is discussed, and the possible implications for an appropriate risk assessment.

scholarly journals Developing Objective Operational Definitions for Monitoring Drought

2009 ◽  
Vol 48 (6) ◽  
pp. 1217-1229 ◽  
Author(s):  
Steven M. Quiring
Keyword(s):  
Water Conservation ◽  
Standardized Precipitation Index ◽  
Meteorological Drought ◽  
Severity Index ◽  
Decision Makers ◽  
Drought Severity ◽  
Specific Method ◽  
The Standardized Precipitation Index ◽  
Spatially Variant ◽  
Objective Methodology

Abstract Drought is a complex phenomenon that is difficult to accurately describe because its definition is both spatially variant and context dependent. Decision makers in local, state, and federal agencies commonly use operational drought definitions that are based on specific drought index thresholds to trigger water conservation measures and determine levels of drought assistance. Unfortunately, many state drought plans utilize operational drought definitions that are derived subjectively and therefore may not be appropriate for triggering drought responses. This paper presents an objective methodology for establishing operational drought definitions. The advantages of this methodology are demonstrated by calculating meteorological drought thresholds for the Palmer drought severity index, the standardized precipitation index, and percent of normal precipitation using both station and climate division data from Texas. Results indicate that using subjectively derived operational drought definitions may lead to over- or underestimating true drought severity. Therefore, it is more appropriate to use an objective location-specific method for defining operational drought thresholds.

scholarly journals Seasonal forecasts of droughts in African basins using the Standardized Precipitation Index

2013 ◽  
Vol 17 (6) ◽  
pp. 2359-2373 ◽  
Author(s):  
E. Dutra ◽  
F. Di Giuseppe ◽  
F. Wetterhall ◽  
F. Pappenberger
Keyword(s):  
Real Time ◽  
Lead Time ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Seasonal Forecasting ◽  
Monthly Precipitation ◽  
Seasonal Forecasts ◽  
Blue Nile ◽  
Forecasting System ◽  
The Standardized Precipitation Index

Abstract. Vast parts of Africa rely on the rainy season for livestock and agriculture. Droughts can have a severe impact in these areas, which often have a very low resilience and limited capabilities to mitigate drought impacts. This paper assesses the predictive capabilities of an integrated drought monitoring and seasonal forecasting system (up to 5 months lead time) based on the Standardized Precipitation Index (SPI). The system is constructed by extending near-real-time monthly precipitation fields (ECMWF ERA-Interim reanalysis and the Climate Anomaly Monitoring System–Outgoing Longwave Radiation Precipitation Index, CAMS-OPI) with monthly forecasted fields as provided by the ECMWF seasonal forecasting system. The forecasts were then evaluated over four basins in Africa: the Blue Nile, Limpopo, Upper Niger, and Upper Zambezi. There are significant differences in the quality of the precipitation between the datasets depending on the catchments, and a general statement regarding the best product is difficult to make. The generally low number of rain gauges and their decrease in the recent years limits the verification and monitoring of droughts in the different basins, reinforcing the need for a strong investment on climate monitoring. All the datasets show similar spatial and temporal patterns in southern and north-western Africa, while there is a low correlation in the equatorial area, which makes it difficult to define ground truth and choose an adequate product for monitoring. The seasonal forecasts have a higher reliability and skill in the Blue Nile, Limpopo and Upper Niger in comparison with the Zambezi. This skill and reliability depend strongly on the SPI timescale, and longer timescales have more skill. The ECMWF seasonal forecasts have predictive skill which is higher than using climatology for most regions. In regions where no reliable near-real-time data is available, the seasonal forecast can be used for monitoring (first month of forecast). Furthermore, poor-quality precipitation monitoring products can reduce the potential skill of SPI seasonal forecasts in 2 to 4 months lead time.

scholarly journals Caractérisation à l’aide du SPI de la Sécheresse climatique dans le bassin versant de Ziz (Sud-Est, Maroc)

2018 ◽  
Vol 14 (21) ◽  
pp. 177 ◽  
Author(s):  
Radouan Mehdaoui ◽  
El-Mostafa Mili ◽  
Aziz Seghir
Keyword(s):  
Temporal Variability ◽  
Standardized Precipitation Index ◽  
Winter Season ◽  
Spatial And Temporal Variability ◽  
Drought Period ◽  
North Eastern ◽  
Edge Part ◽  
The Standardized Precipitation Index ◽  
Bassin Versant ◽  
Eastern Edge

This paper analyzes the spatial and temporal variability of drought in winter season in an arid geographical gradient located in the eastern edge part of the Moroccan High Atlas especially at the Ziz watershed. Drought period between 1975 and 2013 were analyzed using the Standardized Precipitation Index (SPI) over 12 months for a 38-year scale. The results indicate that the most important drought by intensity and duration occurred during the 1982/84, 1983/84, 2000/01, and 2004/05 periods are generalized on all stations of the basin with a minimum SPI reached -2.77 at the Taous station. The results indicate that drought in winter have been tied to the dominance of dry circulation with the exception of the frequency of thermodynamic and north-eastern disturbances which are considered unstable aerological conditions. Which occur frequently between February and April of each year for the Errachidia station, Hassan Adakhil Dam, Foum Zaabal, Tillicht, M'Zizl, Arfoud and Taouz.

scholarly journals Long-Term, Gridded Standardized Precipitation Index for Hawai‘i

Data ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 109
Author(s):  
Matthew P. Lucas ◽  
Clay Trauernicht ◽  
Abby G. Frazier ◽  
Tomoaki Miura
Keyword(s):  
High Spatial Resolution ◽  
Standardized Precipitation Index ◽  
Precipitation Index ◽  
Drought Indices ◽  
Drought Severity ◽  
Spatially Explicit ◽  
Historical Period ◽  
The Standardized Precipitation Index ◽  
Climatic Information

Spatially explicit, wall-to-wall rainfall data provide foundational climatic information but alone are inadequate for characterizing meteorological, hydrological, agricultural, or ecological drought. The Standardized Precipitation Index (SPI) is one of the most widely used indicators of drought and defines localized conditions of both drought and excess rainfall based on period-specific (e.g., 1-month, 6-month, 12-month) accumulated precipitation relative to multi-year averages. A 93-year (1920–2012), high-resolution (250 m) gridded dataset of monthly rainfall available for the State of Hawai‘i was used to derive gridded, monthly SPI values for 1-, 3-, 6-, 9-, 12-, 24-, 36-, 48-, and 60-month intervals. Gridded SPI data were validated against independent, station-based calculations of SPI provided by the National Weather Service. The gridded SPI product was also compared with the U.S. Drought Monitor during the overlapping period. This SPI product provides several advantages over currently available drought indices for Hawai‘i in that it has statewide coverage over a long historical period at high spatial resolution to capture fine-scale climatic gradients and monitor changes in local drought severity.

scholarly journals An Intercomparison of Drought Indicators Based on Thermal Remote Sensing and NLDAS-2 Simulations with U.S. Drought Monitor Classifications

2013 ◽  
Vol 14 (4) ◽  
pp. 1035-1056 ◽  
Author(s):  
Martha C. Anderson ◽  
Christopher Hain ◽  
Jason Otkin ◽  
Xiwu Zhan ◽  
Kingtse Mo ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Standardized Precipitation Index ◽  
Fast Response ◽  
Rapid Onset ◽  
Cold Season ◽  
Stress Index ◽  
Drought Severity ◽  
Thermal Remote Sensing ◽  
Temporal Correlations ◽  
The North

Abstract Comparison of multiple hydrologic indicators, derived from independent data sources and modeling approaches, may improve confidence in signals of emerging drought, particularly during periods of rapid onset. This paper compares the evaporative stress index (ESI)—a diagnostic fast-response indicator describing evapotranspiration (ET) deficits derived within a thermal remote sensing energy balance framework—with prognostic estimates of soil moisture (SM), ET, and runoff anomalies generated with the North American Land Data Assimilation System (NLDAS). Widely used empirical indices based on thermal remote sensing [vegetation health index (VHI)] and precipitation percentiles [standardized precipitation index (SPI)] were also included to assess relative performance. Spatial and temporal correlations computed between indices over the contiguous United States were compared with historical drought classifications recorded in the U.S. Drought Monitor (USDM). Based on correlation results, improved forms for the ESI were identified, incorporating a Penman–Monteith reference ET scaling flux and implementing a temporal smoothing algorithm at the pixel level. Of all indices evaluated, anomalies in the NLDAS ensemble-averaged SM provided the highest correlations with USDM drought classes, while the ESI yielded the best performance of the remote sensing indices. The VHI provided reasonable correlations, except under conditions of energy-limited vegetation growth during the cold season and at high latitudes. Change indices computed from ESI and SM time series agree well, and in combination offer a good indicator of change in drought severity class in the USDM, often preceding USDM class deterioration by several weeks. Results suggest that a merged ESI–SM change indicator may provide valuable early warning of rapidly evolving “flash drought” conditions.

scholarly journals Evaluation of temporal drought variation and projection in a tropical river basin of Kerala

2020 ◽  
Vol 11 (S1) ◽  
pp. 115-132 ◽  
Author(s):  
M. A. Jincy Rose ◽  
N. R. Chithra
Keyword(s):  
River Basin ◽  
Standardized Precipitation Index ◽  
Drought Severity ◽  
Climate Projections ◽  
Severe Drought ◽  
Tropical River ◽  
The Past ◽  
Drought Conditions ◽  
The Future ◽  
The Standardized Precipitation Index

Abstract Temperature is an indispensable parameter of climate that triggers evapotranspiration and has vital importance in aggravating drought severity. This paper analyses the existence and persistence of drought conditions which are said to prevail in a tropical river basin which was once perennial. Past observed data and future climate projections of precipitation and temperature were used for this purpose. The assessment and projection of this study employ the Standardized Precipitation Evapotranspiration Index (SPEI) compared with that of the Standardized Precipitation Index (SPI). The results indicate the existence of drought in the past and the drought conditions that may persist in the future according to RCP 4.5 and 8.5 scenarios. The past drought years identified in the study were compared with the drought declared years in the state and were found to be matching. The evaluation of the future scenarios unveils the occurrence of drought in the basin ranging from mild to extreme conditions. It has been noted that the number of moderate and severe drought months has increased based on SPEI compared to SPI, indicating the importance of temperature in drought studies. The study can be considered as a plausible scientific remark helpful in risk management and application decisions.

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