Trend analysis of extreme precipitation in the northwestern Highlands of Ethiopia with a case study of Debre Markos

Shang, Hongwei; Yan, Jun; Gebremichael, Mekonnen; Ayalew, Semu Moges

doi:10.5194/hessd-7-8587-2010

Cited by 12 publications

(10 citation statements)

References 22 publications

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“…Previous studies near the Lake Tana basin and other parts of Ethiopia have also found insigni cant trends at di erent spatial and temporal scales. For example, from the trend analysis of 53 years' daily precipitation data in Debre Markos, Shang et al [41] found that there is no increasing trend in the extreme precipitation in Debre Markos. Similarly, Wing et al [42] studied the trends and spatial distribution of the annual and seasonal rainfall in di erent parts of Ethiopia using data from 134 stations of 13 watersheds during 1960 to 2002 and showed no signi cant changes in annual watershed rainfall for any of the watersheds examined, except that a signi cant decline in Kiremt rainfall was recorded in watersheds located in the southwestern and central parts of Ethiopia.…”

Section: Regional Trend Analysismentioning

confidence: 99%

Analysis of Rainfall Trends and Its Relationship with SST Signals in the Lake Tana Basin, Ethiopia

Weldegerima

Zeleke

Simane

et al. 2018

Advances in Meteorology

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The impacts of climate change and climate variability on human life have led the scientific community to monitor the behavior of weather and climate variables at different spatial and temporal scales. This paper explores seasonal and annual trends of rainfall in the Lake Tana basin (LTB) and their teleconnections with global sea surface temperatures (SSTs) over the period between 1979 and 2015. The nonparametric Mann–Kendall test and Sen’s slope estimate are applied to the rainfall data collected from the National Meteorology Agency (NMA) of Ethiopia for detecting and estimating rainfall trends. Additionally, Pearson’s correlation coefficient method is used to determine the effect of SST variations on rainfall. The assessment of rainfall trends indicates that the amount of annual rainfall in the Lake Tana basin is increasing, but the rate of increase is not statistically significant. Seasonal analysis reveals that the smallest amount of rainfall occurs in the Bega season, and this season is getting drier with time. However, the analysis indicates that the other two seasons (Belg and Kiremt) are becoming wetter. The rainfall in Kiremt is increasing significantly (significant at the p=0.05 level) in Debre Tabor station with a rate of 10.20 mm/year. Besides, 78.1% of the total annual rainfall in the basin occurs during this rainy (Kiremt) season, whereas Bega and Belg contribute some 9.4% and 12.5%, respectively. Furthermore, the correlation analysis of rainfall and SSTs indicates that rainfall of the LTB is highly affected by the variations of SSTs.

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Section: Regional Trend Analysismentioning

confidence: 99%

Analysis of Rainfall Trends and Its Relationship with SST Signals in the Lake Tana Basin, Ethiopia

Weldegerima

Zeleke

Simane

et al. 2018

Advances in Meteorology

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“…However, with due attention to the spatial scale at which these changes are occurring covering most parts of the country and also to the fact that much of this has occurred in recent years, we do consider them as robust indicators of the changes occurring in the climatic conditions of Ethiopia. Many past studies on extreme events have reported inconsistent patterns (Seleshi and Camberlin 2006;Bewket and Conway 2007;Rosell and Holmer 2007;Kebede and Bewket 2009;Shang et al 2010;Fig. 7 Trends in the national average extreme precipitation.…”

Section: Extreme Precipitation Trendsmentioning

confidence: 99%

Spatio-temporal variability and trends of precipitation and extreme rainfall events in Ethiopia in 1980–2010

Gummadi

Rao

Seid

et al. 2017

Theor Appl Climatol

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This article summarizes the results from an analysis conducted to investigate the spatio-temporal variability and trends in the rainfall over Ethiopia over a period of 31 years from 1980 to 2010. The data is mostly observed station data supplemented by bias-corrected AgMERRA climate data. Changes in annual and Belg (March-May) and Kiremt (June to September) season rainfalls and rainy days have been analysed over the entire Ethiopia. Rainfall is characterized by high temporal variability with coefficient of variation (CV, %) varying from 9 to 30% in the annual, 9 to 69% during the Kiremt season and 15-55% during the Belg season rainfall amounts. Rainfall variability increased disproportionately as the amount of rainfall declined from 700 to 100 mm or less. No significant trend was observed in the annual rainfall amounts over the country, but increasing and decreasing trends were observed in the seasonal rainfall amounts in some areas. A declining trend is also observed in the number of rainy days especially in Oromia, Benishangul-Gumuz and Gambella regions. Trends in seasonal rainfall indicated a general decline in the Belg season and an increase in the Kiremt season rainfall amounts. The increase in rainfall during the main Kiremt season along with the decrease in the number of rainy days leads to an increase in extreme rainfall events over Ethiopia. The trends in the 95th-percentile rainfall events illustrate that the annual extreme rainfall events are increasing over the eastern and southwestern parts of Ethiopia covering Oromia and Benishangul-Gumuz regions. During the Belg season, extreme rainfall events are mostly observed over central Ethiopia extending towards the southern part of the country while during the Kiremt season, they are observed over parts of Oromia, (covering Borena, Guji, Bali, west Harerge and east Harerge), Somali, Gambella, southern Tigray and Afar regions. Changes in the intensity of extreme rainfall events are mostly observed over southeastern parts of Ethiopia extending to the southwest covering Somali and Oromia regions. Similar trends are also observed in the greatest 3-, 5-and 10day rainfall amounts. Changes in the consecutive dry and wet days showed that consecutive wet days during Belg and Kiremt seasons decreased significantly in many areas in Ethiopia while consecutive dry days increased. The consistency in the trends over large spatial areas confirms the robustness of the trends and serves as a basis for understanding the projected changes in the climate. These results were discussed in relation to their significance to agriculture.

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“…Despite varied results in the magnitude of change observed, a growing body of literature now points to significant trends in precipitation and temperature extremes. For example, a negative trend was observed in seasonal extreme rainfall [25], while mixed trends of changes were reported in rainfall extremes [26][27][28][29]. Several empirical studies suggest positive trends in air temperature and negative trends in rainfall [30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Trends in Extreme Climate Events over Three Agroecological Zones of Southern Ethiopia

Esayas

Simane

Teferi

et al. 2018

Advances in Meteorology

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The study aims to assess trends in extremes of surface temperature and precipitation through the application of the World Meteorological Organization’s (WMO) Expert Team on Climate Change Detection and Indices (ETCCDI) on datasets representing three agroecological zones in Southern Ethiopia. The indices are applied to daily temperature and precipitation data. Nonparametric Sen’s slope estimator and Mann–Kendall’s trend tests are used to detect the magnitude and statistical significance of changes in extreme climate, respectively. All agroecological zones (AEZs) have experienced both positive and negative trends of change in temperature extremes. Over three decades, warmest days, warmest nights, and coldest nights have shown significantly increasing trends except in the midland AEZ where warmest days decreased by 0.017°C/year (p<0.05). Temperature extreme’s magnitude of change is higher in the highland AEZ and lower in the midland AEZ. The trend in the daily temperature range shows statistically significant decrease across AEZs (p<0.05). A decreasing trend in the cold spell duration indicator was observed in all AEZs, and the magnitude of change is 0.667 days/year in lowland (p<0.001), 2.259 days/year in midland, and 1 day/year in highland (p<0.05). On the contrary, the number of very wet days revealed a positive trend both in the midland and highland AEZs (p<0.05). Overall, it is observed that warm extremes are increasing while cold extremes are decreasing, suggesting considerable changes in the AEZs.

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Trend analysis of extreme precipitation in the northwestern Highlands of Ethiopia with a case study of Debre Markos

Cited by 12 publications

References 22 publications

Analysis of Rainfall Trends and Its Relationship with SST Signals in the Lake Tana Basin, Ethiopia

Analysis of Rainfall Trends and Its Relationship with SST Signals in the Lake Tana Basin, Ethiopia

Spatio-temporal variability and trends of precipitation and extreme rainfall events in Ethiopia in 1980–2010

Trends in Extreme Climate Events over Three Agroecological Zones of Southern Ethiopia

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