Droughts are among the most devastating natural hazards affecting arid and semi-arid regions, significantly impacting both the environment and socioeconomic conditions. In the Togdheer Region of Somaliland, frequent and severe droughts necessitate the use of advanced monitoring and analytical methods for effective management and mitigation. This thesis evaluates meteorological droughts using the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) and investigates the influences of the Indian Ocean Dipole (IOD) and the El Niño Southern Oscillation (ENSO). Historical climate data from 1971 to 2022, provided by TerraClimate and the National Oceanic and Atmospheric Administration (NOAA), were analyzed using R software, applying both indices to assess drought characteristics across various timescales and to determine the best-fit distributions for modeling. The analysis reveals significant variability in drought patterns, with both indices identifying several severe drought episodes, including notably prolonged periods from 1980 to 1983 and 2016 to 2018. The SPEI specifically highlighted an increase in drought severity and frequency in recent decades, underscoring the impact of global warming on evapotranspiration rates. In contrast, the SPI, which primarily reflects precipitation, did not show significant overall changes. Correlation analyses indicate that both the IOD and ENSO significantly influence rainfall patterns, with the IOD exhibiting a notable correlation (r = 0.71) with autumn rainfall. Additionally, the analysis revealed a moderate positive correlation (r = 0.35) between the Dipole Mode Index (DMI) and spring SPI, indicating a noteworthy influence of the IOD on spring rainfall. The severe droughts in 1980, 2010, 2016, and 2022 coincided with negative IOD phases, which are linked to reduced rainfall and increased drought severity. Although ENSO's influence was weaker (r = 0.43), its consistent impact is crucial for regional climate modeling. These findings enhance our understanding of drought risk management and strategy development in Somaliland, leveraging significant climatic teleconnections to improve drought predictability and mitigation efforts in the Togdheer Region.

Abatzoglou, J. T., Dobrowski, S. Z., Parks, S. A., & Hegewisch, K. C. (2018). TerraClimate, a high-resolution global dataset of monthly climate and climatic water balance from 1958–2015. Scientific Data, 5(1), 1-12.
Abdulkadir, G. (2017). Assessment of drought recurrence in Somaliland: Causes, impacts and mitigations. Journal Climatology Weather. Forecasting, 5(204), 2–16.
Abiy, A. Z., Melesse, A. M., Seyoum, W. M., & Abtew, W. (2019). Drought and climate teleconnection and drought monitoring. In Extreme Hydrology and Climate Variability (pp. 275–295). Elsevier.
Abram, N. J., Hargreaves, J. A., Wright, N. M., Thirumalai, K., Ummenhofer, C. C., & England, M. H. (2020). Palaeoclimate perspectives on the Indian Ocean dipole. Quaternary Science Reviews, 237, 106302.
Abramowitz, M., Stegun, I. A., & Miller, D. (1965). Handbook of mathematical functions with formulas, graphs and mathematical tables (National Bureau of Standards Applied Mathematics Series No. 55). Journal of Applied Mechanics, 32(1), 239–239.
Adler, J., & Parmryd, I. (2010). Quantifying colocalization by correlation: the Pearson correlation coefficient is superior to the Mander's overlap coefficient. Cytometry Part A, 77(8), 733–742.
AghaKouchak, A., Mirchi, A., Madani, K., Di Baldassarre, G., Nazemi, A., Alborzi, A., Anjileli, H., Azarderakhsh, M., Chiang, F., & Hassanzadeh, E. (2021). Anthropogenic drought: definition, challenges, and opportunities. In: Wiley Online Library.
Agrawala, S., Barlow, M., Cullen, H., & Lyon, B. (2001). The drought and humanitarian crisis in central and southwest Asia: A climate perspective. (IRI Special Report No. 01-11). International Research Institute for Climate Prediction., 245–259.
Ahmad, M., Sinclair, C., & Werritty, A. (1988). Log-logistic flood frequency analysis. Journal of Hydrology, 98(3–4), 205–224.
Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration-Guidelines for computing crop water requirements–FAO Irrigation and drainage paper 56. Fao, Rome, 300(9), D05109.
Anderson, W., Cook, B. I., Slinski, K., Schwarzwald, K., McNally, A., & Funk, C. (2023). Multiyear La Niña events and multiseason drought in the Horn of Africa. Journal of Hydrometeorology, 24(1), 119–131.
Anteneh, Z., MelesseAM, S. W., & Abtew, W. (2019). Drought and climate teleconnection and drought monitoring. Gabriel Senay, Extreme Hydrology and Climate Variability, Elsevier, 275–295.
Anyamba, A., Glennie, E., & Small, J. (2018). Teleconnections and interannual transitions as observed in African vegetation: 2015–2017. Remote Sensing, 10(7), 1038.
Artusi, R., Verderio, P., & Marubini, E. (2002). Bravais-Pearson and Spearman correlation coefficients: meaning, test of hypothesis and confidence interval. The International Journal of Biological Markers, 17(2), 148-151.
Ault, T. R. (2020). On the essentials of drought in a changing climate. Science, 368(6488), 256–260.
Awchi, T. A., & Kalyana, M. M. (2017). Meteorological drought analysis in northern Iraq using SPI and GIS. Sustainable Water Resources Management, 3, 451–463.
Beguería, S., Vicente‐Serrano, S. M., Reig, F., & Latorre, B. (2014). Standardized precipitation evapotranspiration index (SPEI) revisited: parameter fitting, evapotranspiration models, tools, datasets and drought monitoring. International journal of climatology, 34(10), 3001–3023.
Bland, J. M., & Altman, D. G. (2010). Statistical methods for assessing agreement between two methods of clinical measurement. International Journal of Nursing Studies, 47(8), 931–936.
Bond, N. R., Lake, P. S., & Arthington, A. H. (2008). The impacts of drought on freshwater ecosystems: an Australian perspective. Hydrobiologia, 600, 3–16.
Cai, W., Wu, L., Lengaigne, M., Li, T., McGregor, S., Kug, J.-S., Yu, J.-Y., Stuecker, M. F., Santoso, A., & Li, X. (2019). Pantropical climate interactions. Science, 363(6430), 4236.
Chen, S.-T., Yang, T.-C., Kuo, C.-M., Kuo, C.-H., & Yu, P.-S. (2013). Probabilistic Drought Forecasting in Southern Taiwan Using El Niño-Southern Oscillation Index. Terrestrial, Atmospheric & Oceanic Sciences, 24(5), 911–924.
Cherchi, A., Terray, P., Ratna, S. B., Sankar, S., Sooraj, K., & Behera, S. (2021). Indian Ocean Dipole influence on Indian summer monsoon and ENSO: A review.Indian summer monsoon variability. El Nino teleconnections and beyond, 157–182.
Davey, M., Brookshaw, A., & Ineson, S. (2014). The probability of the impact of ENSO on precipitation and near-surface temperature. Climate Risk Management, 1, 5–24.
Dutra, E., Magnusson, L., Wetterhall, F., Cloke, H. L., Balsamo, G., Boussetta, S., & Pappenberger, F. (2013). The 2010–2011 drought in the Horn of Africa in ECMWF reanalysis and seasonal forecast products. International Journal of Climatology, 33(7), 1720–1729.
Endris, H. S., Lennard, C., Hewitson, B., Dosio, A., Nikulin, G., & Artan, G. A. (2019). Future changes in rainfall associated with ENSO, IOD and changes in the mean state over Eastern Africa. Climate dynamics, 52, 2029–2053.
Fang, S., Qi, Y., Yu, W., Liang, H., Han, G., Li, Q., Shen, S., Zhou, G., & Shi, G. (2016). Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China. International Journal of Climatology issue, 1925.
Fick, S. E., & Hijmans, R. J. (2017). WorldClim 2: new 1‐km spatial resolution climate surfaces for global land areas. International journal of climatology, 37(12), 4302–4315.
Forootan, E., Khaki, M., Schumacher, M., Wulfmeyer, V., Mehrnegar, N., van Dijk, A. I., Brocca, L., Farzaneh, S., Akinluyi, F., & Ramillien, G. (2019). Understanding the global hydrological droughts of 2003–2016 and their relationships with teleconnections. Science of the Total Environment, 650, 2587-2604.
Funk, C., Fink, A. H., Harrison, L., Segele, Z., Endris, H. S., Galu, G., Korecha, D., & Nicholson, S. (2023). Frequent but predictable droughts in East Africa driven by a Walker circulation intensification. Earth's Future, 11(11), e2022EF003454.
Gooding, P. (2022). ENSO, IOD, Drought, and Floods in Equatorial Eastern Africa, 1876–1878. In Droughts, Floods, and Global Climatic Anomalies in the Indian Ocean World (pp. 259–287). Springer.
Guhathakurta, Pulak, & Wagh, N. (2022). Analysis of Droughts in South-West Indian Ocean Countries using SPI and SPEI and their Relationship with Global SST. JNRD-Journal of Natural Resources and Development, 12, 60–81.
Haile, G. G., Tang, Q., Leng, G., Jia, G., Wang, J., Cai, D., Sun, S., Baniya, B., & Zhang, Q. (2020). Long-term spatiotemporal variation of drought patterns over the Greater Horn of Africa. Science of the Total Environment, 704, 135299.
Haile, G. G., Tang, Q., Sun, S., Huang, Z., Zhang, X., & Liu, X. (2019a). Droughts in East Africa: Causes, impacts and resilience. Earth-science reviews, 193, 146–161.
Haile, G. G., Tang, Q., Sun, S., Huang, Z., Zhang, X., & Liu, X. (2019b). Droughts in East Africa: Causes, impacts and resilience. Earth-science reviews, 193, 146-161.
Hassan, W. U., & Nayak, M. A. (2020). Global teleconnections in droughts caused by oceanic and atmospheric circulation patterns. Environmental Research Letters, 16(1), 014007.
Jiang, W., Wang, L., Feng, L., Zhang, M., & Yao, R. (2019). Drought characteristics and its impact on changes in surface vegetation from 1981 to 2015 in the Yangtze River Basin, China. International Journal of Climatology, 40(7), 3380–3397.
Jiang, Y., Zhou, L., Roundy, P. E., Hua, W., & Raghavendra, A. (2021). Increasing influence of Indian Ocean dipole on precipitation over central equatorial Africa. Geophysical Research Letters, 48(8), e2020GL092370.
Jilan, J., Yimin, L., Jianping, L., & Renhe, Z. (2021). Indian Ocean Dipole: a review and perspective. Advances in Earth Science, 36(6), 579.
Khan, S., Piao, S., Zheng, G., Khan, I. U., Bradley, D., Khan, S., & Song, Y. (2021). Sea surface temperature variability over the tropical Indian Ocean during the ENSO and IOD events in 2016 and 2017. Atmosphere, 12(5), 587.
Li, L., She, D., Zheng, H., Lin, P., & Yang, Z.-L. (2020). Elucidating diverse drought characteristics from two meteorological drought indices (SPI and SPEI) in China. Journal of Hydrometeorology, 21(7), 1513–1530.
Lim, E.-P., & Hendon, H. H. (2017). Causes and predictability of the negative Indian Ocean Dipole and its impact on La Niña during 2016. Scientific Reports, 7(1), 12619.
Lu, B., Ren, H.-L., Scaife, A. A., Wu, J., Dunstone, N., Smith, D., Wan, J., Eade, R., MacLachlan, C., & Gordon, M. (2018). An extreme negative Indian Ocean Dipole event in 2016: dynamics and predictability. Climate Dynamics, 51, 89–100.
Lyon, B. (2014). Seasonal drought in the Greater Horn of Africa and its recent increase during the March–May long rains. Journal of Climate, 27(21), 7953–7975.
Ma, Q., Li, Y., Liu, F., Feng, H., Biswas, A., & Zhang, Q. (2023). SPEI and multi-threshold run theory based drought analysis using multi-source products in China. Journal of Hydrology, 616, 128737.
MacFarland, T. W., Yates, J. M., MacFarland, T. W., & Yates, J. M. (2016). Chi-Square. Introduction to Nonparametric Statistics for the Biological Sciences Using R, 77–102.
Malakiya, A. D., & Suryanarayana, T. (2016). Assessment of drought using standardized precipitation index (SPI) and reconnaissance drought index (RDI): a case study of Amreli District. International Journal of Science and Research, 5(8), 1995–2002.
Manatsa, D., Chipindu, B., & Behera, S. K. (2012). Shifts in IOD and their impacts on association with East Africa rainfall. Theoretical and applied climatology, 110, 115–128.
Marchant, R., Mumbi, C., Behera, S., & Yamagata, T. (2007). The Indian Ocean dipole–the unsung driver of climatic variability in East Africa. African Journal of Ecology, 45(1), 4–16.
McKee, Thomas B, Doesken, Nolan J, Kleist, & John. (1993). The relationship of drought frequency and duration to time scales. Proceedings of the 8th Conference on Applied Climatology,
Mindrila, D., Balentyne, P., & Tables, T.-W. (2013). The Chi Square Test. The Basic Practice of Statistics. 6th ed. New York: WH Freeman.
Mishra, A. K., & Singh, V. P. (2010). A review of drought concepts. Journal of hydrology, 391(1-2), 202–216.
Mpelasoka, F., Awange, J. L., & Zerihun, A. (2018). Influence of coupled ocean-atmosphere phenomena on the Greater Horn of Africa droughts and their implications. Science of the Total Environment, 610, 691–702.
Muchiri, P. (2007). Inventory of Hydro-Meteorological Data of Somalia. SWALIM technical reports.
Musei, S. K., Nyaga, J. M., & Dubow, A. Z. (2021). SPEI-based spatial and temporal evaluation of drought in Somalia. Journal of Arid Environments, 184, 104296.
Naumann, G., Alfieri, L., Wyser, K., Mentaschi, L., Betts, R. A., Carrao, H., Spinoni, J., Vogt, J., & Feyen, L. (2018). Global changes in drought conditions under different levels of warming. Geophysical Research Letters, 45(7), 3285–3296.
Nicholson, S. E. (2017). Climate and climatic variability of rainfall over eastern Africa. Reviews of Geophysics, 55(3), 590–635.
Omar, A. A., Chiang, J.-L., & Daud, B. H. (2023). Spatiotemporal Analysis of Meteorological Drought Using Standardized Precipitation Index (SPI) in Gabiley Region, Somaliland. Journal of Geoscience and Environment Protection, 11(5), 47–59.
Owiti, Z., Ogallo, L. A., & Mutemi, J. (2008). Linkages between the Indian Ocean Dipole and East African seasonal rainfall anomalies. Journal of Kenya Meteorological Society Volume, 2(1), 102–115.
Palmer, W. C. (1965). Meteorological drought. U.S. Weather Bureau Res. Paper No. 45.
Park, S., Kang, D., Yoo, C., Im, J., & Lee, M.-I. (2020). Recent ENSO influence on East African drought during rainy seasons through the synergistic use of satellite and reanalysis data. ISPRS Journal of Photogrammetry and Remote Sensing, 162, 17–26.
Pei, Z., Fang, S., Wang, L., & Yang, W. (2020). Comparative analysis of drought indicated by the SPI and SPEI at various timescales in inner Mongolia, China. Water, 12(7), 1925.
Philip, S., Kew, S. F., van Oldenborgh, G. J., Otto, F., O′Keefe, S., Haustein, K., King, A., Zegeye, A., Eshetu, Z., & Hailemariam, K. (2018). Attribution Analysis of the Ethiopian Drought of 2015. Journal of Climate, 2465–2486.
Riebsame, W. E. (2019). Drought and natural resources management in the United States: impacts and implications of the 1987–89 drought. Routledge.
Shah, D., Shah, H. L., Dave, H. M., & Mishra, V. (2021). Contrasting influence of human activities on agricultural and hydrological droughts in India. Science of The Total Environment, 774, 144959.
Shankar, P. M. (2019). Pedagogy of chi‐square goodness of fit test for continuous distributions. Computer Applications in Engineering Education, 27(3), 679–689.
Shatanawi, K., Rahbeh, M., & Shatanawi, M. (2013). Characterizing, Monitoring and Forecasting of Drought in Jordan River Basin. Journal of Water Resource and Protection, 5, 1192–1202.
Sheffield, J., Wood, E. F., & Roderick, M. L. (2012). Little change in global drought over the past 60 years. Nature, 491(7424), 435–438.
Singh, V., Guo, H., & Yu, F. (1993). Parameter estimation for 3-parameter log-logistic distribution (LLD3) by Pome. Stochastic Hydrology and Hydraulics, 7, 163–177.
Spinoni, J., Naumann, G., Carrao, H., Barbosa, P., & Vogt, J. (2014). World drought frequency, duration, and severity for 1951–2010. International Journal of Climatology, 34(8), 2792–2804.
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.
Tian, Z., Li, T., Jiang, D., & Chen, L. (2017). Causes of ENSO weakening during the Mid-Holocene. Journal of Climate, 30(17), 7049–7070.
Tirivarombo, S., Osupile, D., & Eliasson, P. (2018). Drought monitoring and analysis: standardised precipitation evapotranspiration index (SPEI) and standardised precipitation index (SPI). Physics and Chemistry of the Earth, Parts A/B/C, 106, 1–10.
UN Secretariat General. (1994). United Nations convention to combat drought and desertification in countries experiencing serious droughts and/or desertification, particularly in Africa. United Nations.
Vicente-Serrano, S., 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.
Vicente-Serrano, S. M., Beguería, S., Gimeno, L., Eklundh, L., Giuliani, G., Weston, D., El Kenawy, A., López-Moreno, J. I., Nieto, R., & Ayenew, T. (2012). Challenges for drought mitigation in Africa: The potential use of geospatial data and drought information systems. Applied Geography, 34, 471–486.
Wang, C., Deser, C., Yu, J.-Y., DiNezio, P., & Clement, A. (2017). El Niño and southern oscillation (ENSO): a review. Coral reefs of the eastern tropical Pacific: Persistence and loss in a dynamic environment, 85–106.
Wang, H., Chen, Y., Pan, Y., Chen, Z., & Ren, Z. (2019). Assessment of candidate distributions for SPI/SPEI and sensitivity of drought to climatic variables in China. International Journal of Climatology, 39(11), 4392–4412.
Wang, Q., Wu, J., Lei, T., He, B., Wu, Z., Liu, M., Mo, X., Geng, G., Li, X., & Zhou, H. (2014). Temporal-spatial characteristics of severe drought events and their impact on agriculture on a global scale. Quaternary International, 349, 10–21.
Weine, E., McPeek, M. S., & Abney, M. (2023). Application of equal local levels to improve QQ plot testing bands with R package qqconf. Journal of statistical software, 106(10), 1–31.
Wilhite, D. A. (2000). Drought as a Natural Hazard: Concepts and definitions. Drought: A Global Assessment, 1(1), 3–18.
Wilhite, D. A., & Glantz, M. H. (1985). Understanding: the drought phenomenon: the role of definitions. Water international, 10(3), 111–120.
Wilhite, D. A., & Pulwarty, R. S. (2005). Drought and water crises: lessons learned and the road ahead. Drought and water crises: science, technology, and management issues, 389–398.
Wilk, M. B., & Gnanadesikan, R. (1968). Probability plotting methods for the analysis for the analysis of data. Biometrika, 55(1), 1–17.
Yang, H., & Huntingford, C. (2018). Brief communication: drought likelihood for East Africa. Natural Hazards and Earth System Sciences, 18(2), 491–497.
Yevjevich, V. M. (1967). An objective approach to definitions and investigations of continental hydrologic droughts (Vol. 23). Colorado State University Fort Collins, CO, USA.
Yuan, X., Wang, Y., Ji, P., Wu, P., Sheffield, J., & Otkin, J. A. (2023). A global transition to flash droughts under climate change. Science, 380(6641), 187–191.
Zhao, S., & Cook, K. H. (2021a). Influence of Walker circulations on East African rainfall. Climate Dynamics, 56(7), 2127-2147.
Zhao, S., & Cook, K. H. (2021b). Influence of Walker circulations on East African rainfall. Climate Dynamics, 56(7), 2127–2147.