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Assessing spatial variability and trends of droughts in Eastern Algeria using SPI, RDI, PDSI, and MedPDSI—A novel drought index using the FAO56 evapotranspiration method
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Orientador(es)
Resumo(s)
Drought is one of the most severe natural disasters worldwide, but with a particular
emphasis in sub-humid and semi-arid climates. Several indices have been created to appropriately
identify drought’s characteristics and variability. The main objectives of this study consisted of
analyzing the behavior of different indices applied in northeast Algeria and comparing them across a
long-term data set (1961–2014). The SPI and RDI at 9-month time scales were compared to the PDSI
and MedPDSI based on 123 rainfall stations and gridded PET data interpolated to all the locations.
A principal component analysis (PCA) in S-mode with varimax rotation (RPC) was applied to the
monthly values of all indices to analyze the spatiotemporal patterns of droughts. Two principal
components were retained, which identified two sub-regions with coherent differences related to their
distance from the Mediterranean Sea and the UNEP aridity index. Trends in the RPC scores were
assessed using the modified Mann–Kendall (MMK) test and Sen’s slope estimator, which showed
a fundamental difference between the two sub-regions. The RPC of all drought indices showed
trends of decreases in the frequency and severity of droughts in the northern sub-region, and trends
of increases in the frequency and severity of droughts in the southern region, where the climate is
mostly semi-arid and arid. Only a few cases were statistically significant, mostly when using the PDSI
and MedPDSI for the southern sub-region. The spatial patterns of moderate, severe, and extreme
drought occurrences were similar for the SPI and RDI pair of indices based on the probability of
rainfall anomalies, and for the Sc-PDSI and MedPDSI pair based on water balance anomalies. The
interpretation of the spatial variability of droughts, mainly of the extreme ones, was supported by an
analysis of semi-variograms. The novel index MedPDSI compared well with the other indices and
showed advantages of performing the soil water balance following the FAO56 dual Kc method with
the actual olive evapotranspiration instead of PET, and of better explaining the spatial variability
of extreme droughts; in addition, the trends detected were significant for both the northern and
southern sub-regions.
Descrição
Palavras-chave
drought patterns trends PDSI MedPDSI SPI RDI Algeria
Contexto Educativo
Citação
Merabti, A.; Darouich, H.; Paredes, P.; Meddi, M.; Pereira, L.S. Assessing spatial variability and trends of droughts in Eastern Algeria using SPI, RDI, PDSI, and MedPDSI—A novel drought index using the FAO56 evapotranspiration method. Water 2023, 15, 626
Editora
MDPI