Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China

Pei, Zhifang; Fang, Shibo; Wang, Lei; Yang, Wunian

doi:10.3390/w12071925

Cited by 174 publications

(102 citation statements)

References 63 publications

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“…In general, it is well understood that both agricultural and hydrological droughts are modulated by the interactions of climate and river basin characteristics, such as geology, as well as a human influence or any combination thereof (e.g., Van Lanen et al, 2013;Huang et al, 2016;Liu et al, 2016;Van Loon et al, 2019). For example, data show that reservoir operations can have both considerable positive and negative effects on downstream hydrological-drought pattern (e.g., Zhang et al, 2013;Piqué et al, 2016;Wu et al, 2017), which may politically be particularly sensitive for transboundary rivers in arid environments (Al-Faraj and Scholz, 2014;Wan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Roodari

Hrachowitz

Hassanpour

et al. 2021

Hydrol. Earth Syst. Sci.

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Abstract. The transboundary Helmand River basin (HRB) is the main drainage system for large parts of Afghanistan and the Sistan region of Iran. Due to the reliance of this arid region on water from the Helmand River, a better understanding of hydrological-drought pattern and the underlying drivers in the region is critically required for effective management of the available water. The objective of this paper is therefore to analyze and quantify spatiotemporal pattern of drought and the underlying processes in the study region. More specifically we test for the Helmand River basin the following hypotheses for the 1970–2006 period: (1) drought characteristics, including frequency and severity, systematically changed over the study period; (2) the spatial pattern and processes of drought propagation through the Helmand River basin also changed; and (3) the relative roles of climate variability and human influence on changes in hydrological droughts can be quantified. It was found that drought characteristics varied throughout the study period but largely showed no systematic trends. The same was observed for the time series of drought indices SPI (standard precipitation index) and SPEI (standardized precipitation evapotranspiration index), which exhibited considerable spatial coherence and synchronicity throughout the basin, indicating that, overall, droughts similarly affect the entire HRB with few regional or local differences. In contrast, analysis of the SDI (streamflow drought index) exhibited significant negative trends in the lower parts of the basin, indicating an intensification of hydrological droughts. It could be shown that with a mean annual precipitation of ∼ 250 mm yr−1, streamflow deficits and thus hydrological drought throughout the HRB are largely controlled by precipitation deficits, whose annual anomalies on average account for ±50 mm yr−1, or ∼ 20 % of the water balance of the HRB, while anomalies of total evaporative fluxes on average only account for ±20 mm yr−1. Assuming no changes in the reservoir management practices over the study period, the results suggest that the two reservoirs in the HRB only played a minor role for the downstream propagation of streamflow deficits, as indicated by the mean difference between inflow and outflow during drought periods, which did not exceed ∼ 0.5 % of the water balance of the HRB. Irrigation water abstraction had a similarly limited effect on the magnitude of streamflow deficits, accounting for ∼ 10 % of the water balance of the HRB. However, the downstream parts of the HRB moderated the further propagation of streamflow deficits and associated droughts because of the minor effects of reservoir operation and very limited agricultural water in the early decades of the study period. This drought moderation function of the lower basin was gradually and systematically inverted by the end of the study period, when the lower basin eventually amplified the downstream propagation of flow deficits and droughts. Our results provide plausible evidence that this shift from drought moderation to drought amplification in the lower basin is likely a consequence of increased agricultural activity and the associated increases in irrigation water demand, from ∼ 13 mm yr−1 at the beginning of the study period to ∼ 23 mm yr−1 at the end, and thus in spite of being only a minor fraction of the water balance. Overall the results of this study illustrate that flow deficits and the associated droughts in the HRB clearly reflect the dynamic interplay between temporally varying regional differences in hydro-meteorological variables together with subtle and temporally varying effects linked to direct human intervention.

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Section: Introductionmentioning

confidence: 99%

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Roodari

Hrachowitz

Hassanpour

et al. 2021

Hydrol. Earth Syst. Sci.

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“…Standardized Precipitation Index (SPI) is one of the most important indicators used consistently by various researchers and decision-makers to determine and monitor drought intensity. Furthermore, previously reported studies [72][73][74][75] have shown that the historical spatial-temporal distribution of meteorological droughts can be determined using this SPI index. In this study, CHIRPS rainfall data were used to calculate the SPI index from 1989 to 2019, covering each district using a World Meteorological Organization (WMO) tool at different time frames.…”

Section: Standardized Precipitation Index (Spi)mentioning

confidence: 99%

“…As shown in Table 6, it is indicated that the drought can be declared if the DA classes become DA4. This is evidenced by the fact that Sri Lanka experienced severe droughts in 2001, 2009, 2012, and 2016 regarding population exposure and agriculture crop damage [12,14,75].…”

Section: Annual Drought Area Its Classification and Declarationmentioning

confidence: 99%

Satellite-Based Meteorological and Agricultural Drought Monitoring for Agricultural Sustainability in Sri Lanka

2021

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For Sri Lanka, as an agricultural country, a methodical drought monitoring mechanism, including spatial and temporal variations, may significantly contribute to its agricultural sustainability. Investigating long-term meteorological and agricultural drought occurrences in Sri Lanka and assessing drought hazard at the district level are the main objectives of the study. Standardized Precipitation Index (SPI), Rainfall Anomaly Index (RAI), and Vegetation Health Index (VHI) were used as drought indicators to investigate the spatial and temporal distribution of agriculture and metrological droughts. Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data from 1989 to 2019 was used to calculate SPI and RAI. MOD13A1 and MOD11A2 data from Moderate Resolution Imaging Spectroradiometer (MODIS) from 2001 to 2019, were used to generate the Vegetation Condition Index (VCI) and Temperature Condition Index (TCI). Agricultural drought monitoring was done using VHI and generated using the spatial integration of VCI and TCI. Thus, various spatial data analysis techniques were extensively employed for vector and raster data integration and analysis. A methodology has been developed for the drought declaration of the country using the VHI-derived drought area percentage. Accordingly, for a particular year, if the country-wide annual extreme and severe drought area percentage based on VHI drought classes is ≥30%, it can be declared as a drought year. Moreover, administrative districts of Sri Lanka were classified into four hazard classes, No drought, Low drought, Moderate drought, and High drought, using the natural-beak classification scheme for both agricultural and metrological droughts. The findings of this study can be used effectively by the relevant decision-makers for drought risk management (DRM), resilience, sustainable agriculture, and policymaking.

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“…The precipitation of December-February is used to calculate the winter drought index (SPI3-February). Moreover, the short-term and seasonal droughts indices are applicable for agriculture assessment, whereas the long-term drought index is related to hydrological aspects (Almedeij, 2014;Pei et al, 2020). The value of the dryness and wetness condition lies at ≤ −1 and ≥ 1, respectively.…”

Section: Spi Computationmentioning

confidence: 99%

Drought characteristics over Nepal Himalaya and their relationship with climatic indices

Sharma

Hamal

Khadka

et al. 2021

Meteorological Applications

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Understanding drought characteristics is vital for sustainable societal and ecosystem functioning, especially in ongoing climate change. The study investigates the drought characteristics over the Nepal Himalaya using the standardized precipitation index (SPI) based on monthly precipitation data from 220 ground stations between 1980 and 2016 at seasonal and annual timescales. The results show that occurrences of drought are more frequent after the 2000s, intensifying their severity and duration. The cumulative probabilities of short-term (SPI3) and long-term (SPI12) drought during the period 1980-2016 were 17.1% and 23.5%, respectively. The short-term drought over Nepal occurred with an average duration of 2.8 months and a severity of −4.3, whereas for long-term drought the duration and severity were 8.6 months and −13.9, respectively. Meanwhile, the seasonal drought shows that the spring and autumn drought events were slightly higher than summer and winter drought. The wavelet power spectrum shows the variability signals of winter, spring and summer drought were 2-8 and 8-16 years; however, the autumn drought index only varied at 2-8 years. The NINO3.4 is the primary controlling mode of variability for summer and annual drought, whereas the dipole moment index (DMI) is used for the autumn drought at an interannual timescale. The decadal variability of summer and annual drought is linked with the Pacific Decadal Oscillation, whereas winter and spring drought are linked to the Arctic Oscillation. Furthermore, the study contributes to the understanding of the drought characteristics and its controlling factors of variability over Nepal.

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Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China

Cited by 174 publications

References 63 publications

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Satellite-Based Meteorological and Agricultural Drought Monitoring for Agricultural Sustainability in Sri Lanka

Drought characteristics over Nepal Himalaya and their relationship with climatic indices

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