Changes in the frequency and severity of hydrological droughts over Ethiopia from 1960 to 2013

A. M. El Kenawy, M. F. McCabe, S. M. Vicente-Serrano, J. I. López-Moreno, S. M. Robaa


Here we present an analysis of drought occurrence and variability in Ethiopia, based on the monthly precipitation data from the Climate Research Unit (CRU-v3.22) over the period from 1960 to 2013. The drought events were characterized by means of the Standardized Precipitation Index (SPI) applied to precipitation data at a temporal scale of 12 months. At the national scale, the results reveal a statistically significant decrease in the severity of droughts over the 54-year period, a pattern that is mostly attributed to a statistically significant decrease in the frequency of high intensity drought episodes (i.e., extreme and very extreme droughts), compared to moderate droughts. To assess the general patterns of drought evolution, a principal component analysis (PCA) was applied to the SPI series. PCA results indicate a high spatial heterogeneity in the SPI variations over the investigated period, with ten different spatially well-defined regions identified. These PCA components accounted for 72.9% of the total variance of drought in the region. These regions also showed considerable differences in the temporal variability of drought, as most of the regions exhibited an increase in wetness conditions in recent decades. In contrast, the regions that receive less than 400 mm of annual precipitation showed a declining  trend, with the largest changes occurring over Afar region. Generally, the highly elevated regions over the central Ethiopian Highlands showed the weakest changes, compared to the lowlands. This study confirms the local character of drought evolution over Ethiopia, providing evidence for policy makers to adopt appropriate local policies to cope with the risks of drought. Over Ethiopia, the detailed spatial assessment of drought evolution is required for a better understanding of the possible impacts of recurrent drought on agriculture, food production, soil degradation, human settlements and migrations, as well as energy production and water resources management across Ethiopia.


Drought; Standardized Precipitation Index; Precipitation; Variability; Trends; Principal Component Analysis; Ethiopia

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Agnew, C.T. (2000). Using the SPI to identify drought. Drought Network News, 12 (1), 6-12.

Antwi-Agyei, P., Fraser, E.D.G., Dougill, A.J., Stringer, L.C., Simelton, E. 2012. Mapping the vulnerability of crop production to drought in Ghana using rainfall, yield and socioeconomic data. Applied Geography 32 (2), 324-334. Doi:

Arismendi, I., Johnson, S.L., Dunham, J.B., Haggerty, R., Hockman-Wert, D. 2012. The paradox of cooling streams in a warming world: Regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States. Geophysical Research Letters 39 (10). Doi: 10.1029/2012GL051448

Bejarán, R.A., Camilloni, I.A. 2003. Objective method for classifying air masses: an application to the analysis of Buenos Aires’ (Argentina) urban heat island intensity. Theoretical and Applied Climatology 74 (1-2), 93-103. Doi: 10.1007/s00704-002-0714-4

Beltrando, G., Camberlin, P. 1993. Interannual variability of rainfall in the eastern horn of Africa and indicators of atmospheric circulation. International Journal of Climatology 13 (5), 533-546. Doi: 10.1002/joc.3370130505

Bewket, W., Conway, D. 2007. A note on the temporal and spatial variability of rainfall in the drought-prone Amhara region of Ethiopia. International Journal of Climatology 27 (11), 1467-1477. Doi: 10.1002/joc.1481

Boken, V.K. (2009). Improving a drought early warning model for an arid region using a soil-moisture index. Applied Geography 29 (3), 402-408. Doi:

Bonaccorso, B., Bordi, I., Cancelliere, A., Rossi, G., Sutera, A. 2003. Spatial Variability of Drought: An Analysis of the SPI in Sicily. Water Resources Management 17 (4), 273-296. Doi: 10.1023/A:1024716530289

Brando, P.M., Balch, J.K., Nepstad, D.C., Morton, D.C., Putz, F.E., Coe, M.T., . . . Soares-Filho, B.S. 2014. Abrupt increases in Amazonian tree mortality due to drought–fire interactions. Proceedings of the National Academy of Sciences 111 (17), 6347-6352. Doi: 10.1073/pnas.1305499111

Burke, M.B., Miguel, E., Satyanath, S., Dykema, J.A., Lobell, D.B. 2009. Warming increases the risk of civil war in Africa. Proceedings of the National Academy of Sciences 106 (49), 20670-20674. Doi: 10.1073/pnas.0907998106.

Conway, D. 2000. Some aspects of climate variability in the north east Ethiopian Highlands — Wollo and Tigray. SINET — Ethiopian Journal of Science 23, 139–161.

Conway, D., Schipper, E.L.F. 2011. Adaptation to climate change in Africa: Challenges and opportunities identified from Ethiopia. Global Environmental Change 21, 227–237.

Dai, A. 2011. Drought under global warming: a review. Wiley Interdisciplinary Reviews: Climate Change 2 (1), 45-65. Doi: 10.1002/wcc.81

Dai, A. 2013. Increasing drought under global warming in observations and models. Nature Climate Change 3 (1), 52-58.

Dedieu, J.P., Besic, N., Vasile, G., Mathieu, J., Durand, Y., Gottardi, F. 2014. Dry snow analysis in alpine regions using RADARSAT-2 full polarimetry data. Comparison with in situ measurements. Paper presented at the Geoscience and Remote Sensing Symposium (IGARSS), 2014 IEEE International.

Deng, L., McCabe, M.F., Stenchikov, G., Evans, J.P. Kucera, P.A. 2015. Simulation of flash-flood-producing storm events in Saudi Arabia using the weather research and forecasting model. Journal of Hydrometeorology 16 (2), 615-630. Doi: 10.1175/JHM-D-14-0126.1

Diro, G.T., Black, E., Grimes, D.I.F. 2008. Seasonal forecasting of Ethiopian spring rains. Meteorological Applications 15 (1), 73-83. Doi: 10.1002/met.63

Edossa, D., Babel, M., Das Gupta, A. 2010. Drought Analysis in the Awash River Basin, Ethiopia. Water Resources Management 24 (7), 1441-1460. Doi: 10.1007/s11269-009-9508-0

El Kenawy, A., López-Moreno, J.I., Vicente-Serrano, S. 2013. Summer temperature extremes in northeastern Spain: spatial regionalization and links to atmospheric circulation (1960–2006). Theoretical and Applied Climatology 113 (3-4), 387-405. Doi: 10.1007/s00704-012-0797-5

El Kenawy, A.M., McCabe, M.F. 2015. A multi-decadal assessment of the performance of gauge- and model-based rainfall products over Saudi Arabia: climatology, anomalies and trends. International Journal of Climatology. Doi: 10.1002/joc.4374.

Funk, C., Dettinger, M.D., Michaelsen, J.C., Verdin, J.P., Brown, M.E., Barlow, M., Hoell, A. 2008. Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development. Proceedings of the National Academy of Sciences 105 (32), 11081-11086. Doi: 10.1073/pnas.0708196105

Gebrehiwot, T., van der Veen, A., Maathuis, B. 2011. Spatial and temporal assessment of drought in the Northern highlands of Ethiopia. International Journal of Applied Earth Observation and Geoinformation 13 (3), 309-321. Doi:

Griffiths, J.F. (1972). Climates of Africa, World Survey of Climatology, 10. Amsterdam, Elsevier.

Guanghui, W., Xinguang, D., Anyan, H. 2011. Discuss on reference crop evapotranspiration in arid zone based on principal component analysis. Paper presented at the Water Resource and Environmental Protection (ISWREP), 2011 International Symposium.

Harris, I., Jones, P.D., Osborn, T.J., Lister, D.H. 2014. Updated high-resolution grids of monthly climatic observations – the CRU TS3.10 Dataset. International Journal of Climatology 34 (3), 623-642. Doi: 10.1002/joc.3711

Hirschi, M., Seneviratne, S.I., Alexandrov, V., Boberg, F., Boroneant, C., Christensen, O.B., … Stepanek, P. 2011. Observational evidence for soil-moisture impact on hot extremes in southeastern Europe. Nature Geosciences 4 (1), 17-21.

Hoerling, M., Hurrell, J., Eischeid, J., Phillips, A. 2006. Detection and Attribution of Twentieth-Century Northern and Southern African Rainfall Change. Journal of Climate 19 (16), 3989-4008. Doi: 10.1175/JCLI3842.1

Hunt, E. D., Svoboda, M., Wardlow, B., Hubbard, K., Hayes, M. and Arkebauer, T. (2014). Monitoring the effects of rapid onset of drought on non-irrigated maize with agronomic data and climate-based drought indices. Agricultural and Forest Meteorology 191, 1-11. doi:

Ji, L. and Peters, A.J. 2003. Assessing vegetation response to drought in the northern Great Plains using vegetation and drought indices. Remote Sensing of Environment 87 (1), 85-98. Doi:

Kaiser, H.F. 1960. The application of electronic computers to factor analysis. Educational and Psychological Measurement 20, 141-151.

Korecha, D., Barnston, A. G. 2007. Predictability of June–September Rainfall in Ethiopia. Monthly Weather Review 135 (2), 628-650. Doi: 10.1175/MWR3304.1.

Livneh, B., Bohn, T.J., Pierce, D.W., Munoz-Arriola, F., Nijssen, B., Vose, R., Brekke, L. 2015. A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013. Scientific Data 2, 150042. Doi: 10.1038/sdata.2015.42

Llasat, M.C., Ceperuelo, M., Rigo, T. 2007. Rainfall regionalization on the basis of the precipitation convective features using a raingauge network and weather radar observations. Atmospheric Research 83 (2–4), 415-426. Doi:

Lloyd-Hughes, B., Saunders, M.A. 2002. A drought climatology for Europe. International Journal of Climatology 22 (13), 1571-1592. Doi: 10.1002/joc.846

McKee, T.B., Doeskin, N.J., Kleist, J. (1993). The relationship of drought frequency and duration to time scales. Paper presented at the 8th Conf. on Applied Climatology, Anaheim, Canada.

Meinke, H., deVoil, P., Hammer, G.L., Power, S., Allan, R., Stone, R.C., Potgieter, A. 2005. Rainfall Variability at Decadal and Longer Time Scales: Signal or Noise? Journal of Climate 18 (1), 89-96. Doi: 10.1175/JCLI-3263.1

Meze-Hausken, E. 2004. Contrasting climate variability and meteorological drought with perceived drought and climate change in northern Ethiopia. Climate Research 27 (1), 19-31. Doi: 10.3354/cr027019

Mishra, A.K., Singh, V.P. 2010. A review of drought concepts. Journal of Hydrology 391 (1–2), 202-216. Doi:

McSweeney, C., New, M., Lixcano, G. 2007. Ethiopia. UNDP Climate Change Country Profiles report.

Ngongondo, C., Xu, C.Y., Gottschalk, L., Alemaw, B. 2011. Evaluation of spatial and temporal characteristics of rainfall in Malawi: a case of data scarce region. Theoretical and Applied Climatology 106 (1-2), 79-93. Doi: 10.1007/s00704-011-0413-0

Ntale, H.K., Gan, T.Y. 2003. Drought indices and their application to East Africa. International Journal of Climatology 23 (11), 1335-1357. Doi: 10.1002/joc.931

Peel, M.C., Finlayson, B.L., McMahon, T.A. 2007. Updated world map of the Köppen-Geiger climate classification. Hydrology and Earth System Sciences 11 (5), 1633-1644. Doi: 10.5194/hess-11-1633-2007

Peters, J.M., Schumacher, R.S. (2014). Objective Categorization of Heavy-Rain-Producing MCS Synoptic Types by Rotated Principal Component Analysis. Monthly Weather Review 142 (5), 1716-1737. Doi: 10.1175/MWR-D-13-00295.1

Quiring, S.M. 2009. Developing Objective Operational Definitions for Monitoring Drought. Journal of Applied Meteorology and Climatology 48 (6), 1217-1229. Doi: 10.1175/2009JAMC2088.1

Ren, L., Arkin, P., Smith, T.M., Shen, S.S.P. 2013. Global precipitation trends in 1900–2005 from a reconstruction and coupled model simulations. Journal of Geophysical Research: Atmospheres 118 (4), 1679-1689. Doi: 10.1002/jgrd.50212.

Richman, M.B. 1986. Rotation of principal components. Journal of Climatology 6 (3), 293-335. Doi: 10.1002/joc.3370060305.

Santos, J.F., Pulido-Calvo, I., Portela, M.M. (2010). Spatial and temporal variability of droughts in Portugal. Water Resources Research 46 (3). Doi: 10.1029/2009WR008071

Schneider, T., Bischoff, T., Haug, G.H. 2014. Migrations and dynamics of the intertropical convergence zone. Nature 513 (7516), 45-53. Doi: 10.1038/nature13636

Schonwiese, C.D., Rapp, J. 1997. Climate trend atlas of Europe based on observations 1891-1990. Kluwer Academic Publishers, Dordrecht, 228 pp.

Seleshi, Y., Zanke, U. 2004. Recent changes in rainfall and rainy days in Ethiopia. International Journal of Climatology 24 (8), 973-983. Doi: 10.1002/joc.1052.

Shanko, D., Camberlin, P. 1998. The effects of the Southwest Indian Ocean tropical cyclones on Ethiopian drought. International Journal of Climatology 18 (12), 1373-1388. Doi: 10.1002/(SICI)1097-0088(1998100)18:12<1373::AID-JOC313>3.0.CO;2-K

Sheffield, J., Wood, E. 2008. Projected changes in drought occurrence under future global warming from multi-model, multi-scenario, IPCC AR4 simulations. Climate Dynamics 31 (1), 79-105. doi: 10.1007/s00382-007-0340-z

Sheffield, J., Wood, E.F., Chaney, N., Guan, K., Sadri, S., Yuan, X., Ogallo, L. 2014. A Drought Monitoring and Forecasting System for Sub-Sahara African Water Resources and Food Security. Bulletin of the American Meteorological Society 95 (6), 861-882. Doi: 10.1175/BAMS-D-12-00124.1

Sheffield, J., Wood E.F. 2011. Drought: Past Problems and Future Scenarios. Routledge, 224 pp.

Sheffield, J., Wood, E.F., Roderick, M.L. 2012. Little change in global drought over the past 60 years. Nature 491 (7424), 435-438.

Stagge, J.H., Tallaksen, L.M., Gudmundsson, L., Van Loon, A.F., Stahl, K. 2015. Candidate Distributions for Climatological Drought Indices (SPI and SPEI). International Journal of Climatology 35 (13), 4027-4040. Doi: 10.1002/joc.4267

Trenberth, K.E., Dai, A., van der Schrier, G., Jones, P.D., Barichivich, J., Briffa, K.R., Sheffield, J. 2014. Global warming and changes in drought. Nature Climate Change 4 (1), 17-22. doi: 10.1038/nclimate2067

Van Loon, A.F., Laaha, G. 2015. Hydrological drought severity explained by climate and catchment characteristics. Journal of Hydrology 526, 3-14. Doi:

Vicente-Serrano, S.M. 2006. Differences in Spatial Patterns of Drought on Different Time Scales: An Analysis of the Iberian Peninsula. Water Resources Management 20 (1), 37-60. doi: 10.1007/s11269-006-2974-8

Vicente-Serrano, S.M., Cuadrat-Prats, J.M. 2007. Trends in drought intensity and variability in the middle Ebro valley (NE of the Iberian peninsula) during the second half of the twentieth century. Theoretical and Applied Climatology 88 (3-4), 247-258. Doi: 10.1007/s00704-006-0236-6.

Vicente-Serrano, S.M., Beguería, S., Gimeno, L., Eklundh, L., Giuliani, G., Weston, D., Pegram, G.G.S. 2012. Challenges for drought mitigation in Africa: The potential use of geospatial data and drought information systems. Applied Geography 34, 471-486. Doi:

Vicente-Serrano, S.M., Beguería, S., López-Moreno, J.I. 2010. A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index. Journal of Climate 23 (7), 1696-1718. Doi: 10.1175/2009JCLI2909.1

Vicente-Serrano, S.M., Chura, O., López-Moreno, J.I., Azorin-Molina, C., Sanchez-Lorenzo, A., Aguilar, E., Nieto, J.J. 2015a. Spatio-temporal variability of droughts in Bolivia: 1955–2012. International Journal of Climatology 35 (10), 3024-3040. Doi: 10.1002/joc.4190

Vicente-Serrano, S.M., Cabello, D., Tomás-Burguera, M., Martín-Hernández, N., Beguería, S., Azorín-Molina, C., Kenawy, A. 2015b. Drought Variability and Land Degradation in Semiarid Regions: Assessment Using Remote Sensing Data and Drought Indices (1982–2011). Remote Sensing 7 (4), 4391.

Viste, E., Korecha, D., Sorteberg, A. 2013. Recent drought and precipitation tendencies in Ethiopia. Theoretical and Applied Climatology 112 (3-4), 535-551. doi: 10.1007/s00704-012-0746-3

Westra, S., Alexander, L.V., Zwiers, F.W. 2013. Global Increasing Trends in Annual Maximum Daily Precipitation. Journal of Climate 26 (11), 3904-3918. Doi: 10.1175/JCLI-D-12-00502.1

Wilks, D. 2011. Statistical Methods in the Atmospheric Sciences. Academic Press, Cornell University, Ithaca, New York, U.S.A.

Williams, A.P., Funk, C., Michaelsen, J., Rauscher, S., Robertson, I., Wils, T. G., Loader, N. 2012. Recent summer precipitation trends in the Greater Horn of Africa and the emerging role of Indian Ocean sea surface temperature. Climate Dynamics 39 (9-10), 2307-2328. Doi: 10.1007/s00382-011-1222-y.



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