Spatio-temporal assessment of meteorological drought under the influence of varying record length: the case of Upper Blue Nile Basin, Ethiopia

Bayissa, Yared A.; Moges, Semu Ayalew; Xuan, Yunqing; Andel, Schalk Jan van; Maskey, Shreedhar; Solomatine, Dimitri; Griensven, Ann van; Tadesse, Tsegaye

doi:10.1080/02626667.2015.1032291

Cited by 57 publications

(59 citation statements)

References 28 publications

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“…Similarily, there is no statistical evidence for a conclusive decreasing or increasing trend in precipitation extremes (Seleshi and Camberlin, 2006;Shang et al, 2011) as well as in the severity and frequency of meteorological droughts in the basin (Bayissa et al, 2015).…”

Section: Historical Precipitation and Streamflow Trendsmentioning

confidence: 93%

Implications of climate change on hydrological extremes in the Blue Nile basin: A review

Taye

Willems

Block

2015

Journal of Hydrology: Regional Studies

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a b s t r a c tStudy region: The Blue Nile river basin in East Africa. Study focus: This review paper presents the current understanding of hydrological extremes in the Blue Nile River basin under historic and future climate conditions, largely drawing on research outputs over the past decade. Characteristics of precipitation and streamflow extremes, including historic trends and future projections, are considered. New hydrological insights: The review illustrates some discrepancy among research outputs. For the historical context, this is partially related to the period and length of data analyzed and the failure to consider the influence of multi-decadal oscillations. Consequently, we show that annual cycle of Blue Nile flow has not changed in the past five decades. For the future context, discrepancy is partially attributable to the various and differing climate and hydrological models included and the downscaling techniques applied. The need to prudently consider sources of uncertainty and potential causes of bias in historical trend and climate change impact research is highlighted.

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Section: Historical Precipitation and Streamflow Trendsmentioning

confidence: 93%

Implications of climate change on hydrological extremes in the Blue Nile basin: A review

Taye

Willems

Block

2015

Journal of Hydrology: Regional Studies

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“…Although both the equatorial and the summer rainfall regions experienced a decline in the MAM rains (Figure ), the trend was weaker in the latter [e.g., Rosell , ; Mengistu et al ., ]. Four major droughts occurred in this region in 1978/1979, 1984/1985, 1994/1995, and 2003/2004 [ Bayissa et al ., ], but these were not evident in the summer rainfall region as a whole [ Nicholson , ]. At the stations of Combolcha and Hayk in the central Ethiopian highlands rainfall declined by 25% to 30% after 1996 [ Rosell and Holmer , ].…”

Section: Recent Trends and Extreme Eventsmentioning

confidence: 99%

Climate and climatic variability of rainfall over eastern Africa

Nicholson

2017

Reviews of Geophysics

516

425

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This review examines several aspects of the climate of eastern Africa. The climatic commonality throughout the region is the frequent occurrence of drought severe enough to incapacitate the population. Because of recent droughts and evidence of disastrous, long‐term climatic change, the region has become a major focus of meteorological research. This review covers six relevant topics: climatic regionalization, seasonal cycle, intraseasonal variability, interannual variability, recent trends, and seasonal forecasting. What emerges is a markedly different view of the factors modulating rainfall, the dynamics associated with the seasons, and the character of teleconnections within the region and the interrelationships between the various rainy seasons. Some of the most important points are the following. (1) The paradigm of two rainy seasons resulting from the biannual equatorial passage of the Intertropical Convergence Zone is inadequate. (2) The “long rains” should not be treated as a single season, as character, causal factors, and teleconnections are markedly different in each month. (3) The long rains have been declining continuously in recent decades. (4) The Madden‐Julian Oscillation has emerged as a factor in interannual and intraseasonal variability, but the relative strength of Pacific and Indian Ocean anomalies plays a major role in the downward trend. (5) Factors governing the short rains are nonstationary. (6) Droughts have become longer and more intense and tend to continue across rainy seasons, and their causes are not adequately understood. (7) Atmospheric variables provide more reliable seasonal forecasts than the factors traditionally considered in forecast models, such as sea surface temperatures and El Niño–Southern Oscillation.

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“…While there are many such indicators, the Lincoln declaration recommended the adoption of the Standardized Precipitation Index (SPI) as a universal indicator of meteorological droughts [19]. Several studies have adopted this indicator to study meteorological droughts in Ethiopia [16,17,[20][21][22][23][24], and as such, it has been adopted here.…”

Section: Selection Of Meteorological and Agricultural Drought Indicatorsmentioning

confidence: 99%

Comparison of Meteorological- and Agriculture-Related Drought Indicators across Ethiopia

Tsige

Uddameri

Forghanparast

et al. 2019

Water

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Meteorological drought indicators are commonly used for agricultural drought contingency planning in Ethiopia. Agricultural droughts arise due to soil moisture deficits. While these deficits may be caused by meteorological droughts, the timing and duration of agricultural droughts need not coincide with the onset of meteorological droughts due to soil moisture buffering. Similarly, agricultural droughts can persist, even after the cessation of meteorological droughts, due to delayed hydrologic processes. Understanding the relationship between meteorological and agricultural droughts is therefore crucial. An evaluation framework was developed to compare meteorologicaland agriculture-related drought indicators using a suite of exploratory and confirmatory tools. Receiver operator characteristics (ROC) was used to understand the covariation of meteorological and agricultural droughts. Comparisons were carried out between SPI-2, SPEI-2, and Palmer Z-index to assess intraseasonal droughts, and between SPI-6, SPEI-6, and PDSI for full-season evaluations. SPI was seen to correlate well with selected agriculture-related drought indicators, but did not explain all the variability noted in them. The correlation between meteorological and agricultural droughts exhibited spatial variability which varied across indicators. SPI is better suited to predict non-agricultural drought states than agricultural drought states. Differences between agricultural and meteorological droughts must be accounted for in order to devise better drought-preparedness planning.

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Spatio-temporal assessment of meteorological drought under the influence of varying record length: the case of Upper Blue Nile Basin, Ethiopia

Cited by 57 publications

References 28 publications

Implications of climate change on hydrological extremes in the Blue Nile basin: A review

Implications of climate change on hydrological extremes in the Blue Nile basin: A review

Climate and climatic variability of rainfall over eastern Africa

Comparison of Meteorological- and Agriculture-Related Drought Indicators across Ethiopia

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