Drought Monitoring in Chaharmahl-Bakhtiyari Province in Iran

Abstract The monitoring of drought is the most important factor in water resources management. This study focuses on evaluation of the drought characteristics such as intensity, frequency and duration drought using Standardized Precipitation Index (SPI) in different time scales such as: SPI1, SPI3 months, during 1980-2012. The results show that selection of different time scales can be based on management goals and kind of drought. The results of the drought occurrence frequency showed that, with increase of length of time scales, drought duration will increase and maximum frequency was at the normal level and there is no particular procedure in different time scales. Furthermore, Drought patterns maps showed that the northern and central parts of study area had experienced these recent droughts more than other places, and these place have potential to destroy the lands. So, by identification of sensitivity regions can be take appropriate management to prevent damage resulting of drought.

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A novel index for ecological drought monitoring based on ecological water deficit: a case study of Northwestern China

10.5194/egusphere-egu21-5439 ◽

2021 ◽

Author(s):

Tianliang Jiang ◽

Xiaoling Su

Keyword(s):

Water Deficit ◽

Time Scales ◽

Drought Index ◽

Vegetation Index ◽

Standardized Precipitation Index ◽

Northwestern China ◽

Drought Monitoring ◽

Drought Indices ◽

Drought Severity ◽

Different Time Scales

Although the concept of ecological drought was first defined by the Science for Nature and People Partnership (SNAPP) in 2016, there remains no widely accepted drought index for monitoring ecological drought. Therefore, this study constructed a new ecological drought monitoring index, the standardized ecological water deficit index (SEWDI). The SEWDI is based on the difference between ecological water requirements and consumption, referred to as the standardized precipitation index (SPI) method, which was used to monitor ecological drought in Northwestern China (NWRC). The performances of the SEWDI and four widely-used drought indices [standardized root soil moisture index (SSI), self-calibrated Palmer drought index (scPDSI), standardized precipitation-evaporation drought index (SPEI), and SPI) in monitoring ecological drought were evaluated through comparing the Pearson correlations between these indices and the standardized normalized difference vegetation index (SNDVI) under different time scales, wetness, and water use efficiencies (WUEs) of vegetation. Finally, the rotational empirical orthogonal function (REOF) was used to decompose the SEWDI at a 12-month scale in the NWRC during 1982&#8211;2015 to obtain five ecological drought regions. The characteristics of ecological drought in the NWRC, including intensity, duration, and frequency, were extracted using run theory. The results showed that the performance of the SEWDI in monitoring ecological drought was highest among the commonly-used drought indices evaluated under different time scales [average correlation coefficient values (r) between SNDVI and drought indices: SEWDI= 0.34, SSI= 0.24, scPDSI= 0.23, SPI= 0.20, SPEI= 0.18), and the 12-month-scale SEWDI was largely unaffected by wetness and WUE. In addition, the results of the monitoring indicated that serious ecological droughts in the NWRC mainly occurred in 1982&#8211;1986, 1990&#8211;1996, and 2005&#8211;2010, primarily in regions I, II, and V, regions II, and IV, and in region III, IV, and V, respectively. This study provides a robust approach for quantifying ecological drought severity across natural vegetation areas and scientific evidence for governmental decision makers.

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Positive and Negative Phases of the Wintertime North Atlantic Oscillation and Drought Occurrence over Europe: A Multitemporal-Scale Approach

Journal of Climate ◽

10.1175/2007jcli1739.1 ◽

2008 ◽

Vol 21 (6) ◽

pp. 1220-1243 ◽

Cited By ~ 110

Author(s):

J. Ignacio López-Moreno ◽

Sergio M. Vicente-Serrano

Keyword(s):

Twentieth Century ◽

North Atlantic Oscillation ◽

Time Scales ◽

North Atlantic ◽

Standardized Precipitation Index ◽

Opposite Pattern ◽

The North ◽

The Standardized Precipitation Index ◽

Drought Occurrence ◽

Different Time Scales

Abstract In this study, droughts are analyzed using the standardized precipitation index (SPI) at different time scales for all of Europe over the period 1901–2000. The SPI is calculated at different time scales (1–12 months), as are the average values that correspond to negative and positive phases of the North Atlantic Oscillation (NAO). The responses of droughts to the phases of the NAO vary spatially, but the response also depends on the month of the year and the time scale of the analysis. During the positive/negative phases, negative/positive SPI values are generally recorded in southern Europe, with the opposite pattern recorded in northern Europe. In certain regions, significant differences in the SPI are also recorded during spring, summer, and even autumn. In several regions, the magnitude of the average SPI anomalies is noticeably different for the positive and negative phases of the NAO, indicating the asymmetric response of droughts to the NAO. The unstable response of drought occurrence is also demonstrated, at different time scales, to positive and negative phases of the NAO throughout the twentieth century. During the second half of the twentieth century, there is a strengthening of the influence of the positive phases of the NAO on droughts. In contrast, the negative phases show a weaker influence on the SPI during the second half of the twentieth century. This pattern is related to changes in the wintertime sea level pressure fields associated with positive and negative phases of the NAO.

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A Multi-Scale Daily SPEI Dataset for Drought Monitoring at Observation Stations over the Mainland China from 1961 to 2018

10.5194/essd-2020-172 ◽

2020 ◽

Author(s):

Qianfeng Wang ◽

Jingyu Zeng ◽

Junyu Qi ◽

Xuesong Zhang ◽

Yue Zeng ◽

...

Keyword(s):

Spatial Distribution ◽

Time Scales ◽

Natural Hazard ◽

Mainland China ◽

Drought Monitoring ◽

Standardized Precipitation Evapotranspiration Index ◽

Drought Duration ◽

Multi Scale ◽

Drought Conditions ◽

Different Time Scales

Abstract. The monthly Standardized Precipitation Evapotranspiration Index (SPEI) can monitor and assess drought characteristics with one month or longer drought duration. Based on data from 1961 to 2018 at 427 meteorological stations across the mainland China, we developed a daily SPEI dataset to overcome the shortcoming of coarse temporal scale of monthly SPEI. Our dataset not only can identify the start and end dates of drought events, but also can be used to investigate the meteorological, agricultural, hydrological and socioeconomic droughts with different time scales. In the present study, the SPEI data with 3-month scale were taken as a demonstration example to analyze spatial distribution and temporal changes in drought conditions for the mainland China. The SPEI data with 3-month scale showed no obvious intensifying trends in terms of severity, duration, and frequency of drought events from 1961 to 2018. Our drought dataset serves as a unique resource with daily resolution to a variety of research communities including meteorology, geography, and natural hazard studies. The daily SPEI dataset developed is free, open and persistent publicly available from this study. The dataset is publicly available via the figshare portal (Wang et al, 2020), with https://doi.org/10.6084/m9.figshare.12568280.

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

Water ◽

10.3390/w13010082 ◽

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.

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Hydrological response to different time scales of climatological drought: an evaluation of the Standardized Precipitation Index in a mountainous Mediterranean basin

Hydrology and Earth System Sciences ◽

10.5194/hess-9-523-2005 ◽

2005 ◽

Vol 9 (5) ◽

pp. 523-533 ◽

Cited By ~ 156

Author(s):

S. M. Vicente-Serrano ◽

J. I. López-Moreno

Keyword(s):

Time Scales ◽

Hydrological Cycle ◽

Standardized Precipitation Index ◽

Precipitation Index ◽

Drought Indices ◽

Long Time ◽

The Standardized Precipitation Index ◽

Hydrological Droughts ◽

Different Time Scales

Abstract. At present, the Standardized Precipitation Index (SPI) is the most widely used drought index to provide good estimations about the intensity, magnitude and spatial extent of droughts. The main advantage of the SPI in comparison with other indices is the fact that the SPI enables both determination of drought conditions at different time scales and monitoring of different drought types. It is widely accepted that SPI time scales affect different sub-systems in the hydrological cycle due to the fact that the response of the different water usable sources to precipitation shortages can be very different. The long time scales of SPI are related to hydrological droughts (river flows and reservoir storages). Nevertheless, few analyses empirically verify these statements or the usefulness of the SPI time scales to monitor drought. In this paper, the SPI at different time scales is compared with surface hydrological variables in a big closed basin located in the central Spanish Pyrenees. We provide evidence about the way in which the longer (>12 months) SPI time scales may not be useful for drought quantification in this area. In general, the surface flows respond to short SPI time scales whereas the reservoir storages respond to longer time scales (7–10 months). Nevertheless, important seasonal differences can be identified in the SPI-usable water sources relationships. This suggests that it is necessary to test the drought indices and time scales in relation to their usefulness for monitoring different drought types under different environmental conditions and water demand situations.

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The Use of a High-Resolution Standardized Precipitation Index for Drought Monitoring and Assessment

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-10-05015.1 ◽

2012 ◽

Vol 51 (1) ◽

pp. 68-83 ◽

Cited By ~ 12

Author(s):

D. Brent McRoberts ◽

John W. Nielsen-Gammon

Keyword(s):

High Resolution ◽

Time Scales ◽

Standardized Precipitation Index ◽

Precipitation Index ◽

Regional Frequency Analysis ◽

Drought Monitoring ◽

Precipitation Data ◽

Monitoring Tool ◽

Daily Precipitation Data ◽

Pearson Type

AbstractA high-resolution drought-monitoring tool was developed to assess drought on multiple time scales using the standardized precipitation index (SPI). Daily precipitation data at 4-km resolution are obtained from the Advanced Hydrologic Prediction Service multisensor precipitation estimates (MPE) and are aggregated on several time scales. Daily station precipitation data available from the Cooperative Observer Program (COOP) provide the historical context for the MPE precipitation data. Pearson type-III distribution parameters were interpolated to the 4-km grid on the basis of a regional frequency analysis of the COOP stations and L-moment ratios of the precipitation data. The resulting high-resolution SPI data can be used as guidance for the U.S. Drought Monitor at the subcounty scale in areas where local precipitation is the primary driver of drought. The temporal flexibility and spatial resolution of the drought-monitoring tool are used to illustrate the onset, intensity, and termination of the 2008–09 Texas drought, and the tool is shown to provide better county- and subcounty-scale information than do gauge-based products.

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When temporal attention lacks confidence

10.1101/496232 ◽

2018 ◽

Author(s):

Samuel Recht ◽

Pascal Mamassian ◽

Vincent de Gardelle

Keyword(s):

Decision Making ◽

Attentional Blink ◽

Time Scales ◽

Item Selection ◽

Temporal Attention ◽

Confidence Judgments ◽

High Level ◽

Selective Process ◽

Different Time Scales ◽

Selection Of

AbstractAccurate decision-making requires estimating the uncertainty of perceptual events. Temporal attention is known to enhance the selection of a stimulus at a relevant time, but how does this selective process affect a decision’s confidence? Here, we adapted an “Attentional blink” paradigm to investigate the effect of temporal attention on confidence judgments. In a RSVP stream of letters, two targets were cued to induce two successive attentional episodes. We found that the confidence ratings given to an item systematically followed the probability with which this item was reported. This coupling made confidence oblivious to selection delays usually observed when the two targets were separated by long intervals (249ms to 747ms). In particular, during this period, confidence was higher for more delayed item selection. One exception to this relationship between confidence and temporal selection was found when the second target appeared soon after (83ms) the first attentional episode. Here, a strong under-confidence bias was observed. Importantly, however, this early confidence bias did not impact confidence sensitivity in discriminating correct and erroneous responses. These results suggest that temporal attention and confidence can operate at different time scales, a difference which seems to reflect high-level heuristic biases rather than segregated processes for decision and confidence evidence.

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Regional and Seasonal Precipitation and Drought Trends in Ganga–Brahmaputra Basin

Water ◽

10.3390/w13162218 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2218

Author(s):

Bikram Parajuli ◽

Xiang Zhang ◽

Sudip Deuja ◽

Yingbing Liu

Keyword(s):

Spatial Pattern ◽

Time Scales ◽

Standardized Precipitation Index ◽

Monthly Precipitation ◽

Seasonal Precipitation ◽

Precipitation Data ◽

Rain Gauges ◽

Geographical Regions ◽

Brahmaputra Basin ◽

Different Time Scales

Satellite-based precipitation products can be a better alternative of rain gauges for hydro-meteorological studies in data-poor regions. This study aimed to evaluate how regional and seasonal precipitation and drought patterns had changed in the Ganga–Brahmaputra Basin between 1983 and 2020 with PERSIANN-CDR precipitation data. The spatial pattern of winter drought, monsoon drought, and Standardized Precipitation Index (SPI) calculated for different time scales were evaluated using principal component analysis. Ganga–Brahmaputra is one of the most populated river basins that flows through different geographical regions. Rain gauges are heterogeneously distributed in the basin due to its complex orography, highlighting the significance of gridded precipitation products over gauge observations for climate studies. Annual and monthly precipitation trends between 1983 and 2020 were evaluated using the original and modified Mann–Kendall trend test, and annual precipitation in the basin was found to be declining at a rate of 5.8 mm/year. An increasing trend was observed in pre-monsoon rainfall, whereas precipitation exhibited a decreasing trend for other months. Results of the Pettitt test showed precipitation time series was inhomogeneous and changepoint occurred around 2000. Decreasing trends of SPI indicated increasing frequency and intensity of drought events. Winter drought showed a clear spatial pattern in the basin; however, SPIs calculated for different time scales and monsoon drought had complex spatial patterns. This study demonstrates the applicability of satellite-based PERSIANN-CDR precipitation data in climate research in the Ganga–Brahmaputra Basin.

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Design droughts as planning tool for ecosystem establishment in post-mining landscapes

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-11-4809-2014 ◽

2014 ◽

Vol 11 (5) ◽

pp. 4809-4849 ◽

Cited By ~ 3

Author(s):

D. Halwatura ◽

A. M. Lechner ◽

S. Arnold

Keyword(s):

Time Scales ◽

Standardized Precipitation Index ◽

Distribution Functions ◽

Drought Indices ◽

Minor Role ◽

Short Term ◽

Eastern Australia ◽

Recurrence Intervals ◽

Different Time Scales

Abstract. Eastern Australia has considerable mineral and energy resources and areas of high biodiversity value co-occurring over a broad range of agro-climatic environments. Water is the primary abiotic stressor for (agro)ecosystems in many parts of Eastern Australia. In the context of mined land rehabilitation quantifying the severity-duration-frequency (SDF) of droughts is crucial for successful ecosystem rehabilitation to overcome challenges of early vegetation establishment and long-term ecosystem resilience. The objective of this study was to quantify the SDF of short-term and long-term drought events of 11 selected locations across a broad range of agro-climatic environments in Eastern Australia by using three drought indices at different time scales: the Standardized Precipitation Index (SPI), the Reconnaissance Drought Index (RDI), and the Standardized Precipitation-Evapotranspiration Index (SPEI). Based on the indices we derived bivariate distribution functions of drought severity and duration, and estimated the recurrence intervals of drought events at different time scales. The correlation between the simple SPI and the more complex SPEI or RDI was stronger for the tropical and temperate locations than for the arid locations, indicating that SPEI or RDI can be replaced by SPI if evaporation plays a minor role for plant available water. Both short-term and long-term droughts were most severe and prolonged, and occurred most frequently in arid regions, but were relatively rare in tropical and temperate regions. Our approach is similar to intensity-duration-frequency (IDF) analyses of rainfall crucial to design infrastructure. In this regard, we propose to apply SDF analyses of droughts to design ecosystem components in post-mining landscapes. Together with design rainfalls, design droughts should be used to assess rehabilitation strategies and ecological management based on drought recurrence intervals, thereby minimising the risk of failure of initial ecosystem establishment due to ignorance of fundamental abiotic and site-specific environmental barriers.

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Hydrological response to different time scales of climatological drought: an evaluation of the standardized precipitation index in a mountainous mediterranean basin

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-2-1221-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 1221-1246 ◽

Cited By ~ 13

Author(s):

S. M. Vicente-Serrano ◽

J. I. López-Moreno

Keyword(s):

Time Scales ◽

Hydrological Cycle ◽

Standardized Precipitation Index ◽

Precipitation Index ◽

Drought Indices ◽

Long Time ◽

The Standardized Precipitation Index ◽

Hydrological Droughts ◽

Different Time Scales

Abstract. At present, the Standardized Precipitation Index (SPI) is the most widely used drought index to provide good estimations about the intensity, magnitude and spatial extent of droughts. The main advantage of the SPI in comparison with other indices is the fact that the SPI enables both determination of drought conditions at different time scales and monitoring of different drought types. It is widely accepted that SPI time scales affect different sub-systems in the hydrological cycle due to the fact that the response of the different water usable sources to precipitation shortages can be very different. The long time scales of SPI are related to hydrological droughts (river flows and reservoir storages). Nevertheless, few analyses empirically verify these statements or the usefulness of the SPI time scales to monitor drought. In this paper, the SPI at different time scales is compared with surface hydrological variables in a big closed basin located in the central Spanish Pyrenees. We provide evidence about the way in which the higher (>12 months) SPI time scales may not be useful for drought quantification in this area. In general, the surface flows respond to short SPI time scales whereas the reservoir storages respond to higher time scales (7–10 months). Nevertheless, important seasonal differences can be identified in the SPI-usable water sources relationships. This suggests that it is necessary to test the drought indices and time scales in relation to their usefulness for monitoring different drought types under different environmental conditions and water demand situations.

Download Full-text