Horn Of Africa Research Articles

Rapid Learning for Lasting Change: Accelerated Basic Education in Post-Conflict, Somalia

This paper extensively examines the comparative learning outcomes and impact of Alternative Basic Education (ABE) in conflict-affected regions, focusing the Bar ama Baro (BAB) initiative in Somalia. With assistance from the United States Agency for International Development (USAID), this initiative successfully enrolled over 100,000 children who were not attending school, while emphasizing the necessity of equal educational opportunities regardless of gender. The primary aim of the study is to contrast the theoretical understanding of Alternative Basic Education with the practical realities observed during the implementation of the USAID-Bar ama Baro program in Somalia. The paper analyzes the collaborative efforts of the Bar ama Baro initiative alongside USAID and Somali education authorities, stressing the importance of providing quality education opportunity that is appropriate, inclusive, adequate, and accessible to all genders. It draws on interview data from 200 participants involved with Bar ama Baro to show how this significant initiative was experienced and what was learned. The study encompasses an in-depth research and literature review demonstrating the significance of Alternative Basic Education during emergencies, facilitating a smooth transition to formal education. The paper also analyzes the significance and effective strategies for addressing the educational needs of developing countries. Furthermore, it assesses the level of basic education in Somalia in comparison to other countries within the Horn of Africa and the African continent. The paper offers educational stakeholders, researchers, and policymakers with a framework to initiate and deliver educational services during emergencies. The paper also recommends collaboration among governments, educational support organizations, researchers, and other education stakeholders to successfully implement and assess main advantages of Alternative Basic Education.

Unveiling the Dynamics and Sustainability of the Nubian Aquifer System in El-Marashda, Egypt Through Geophysical, and Hydrogeochemical Investigations

AbstractThis research investigates the geophysical, hydrogeochemical, and geological characteristics of the Nubian Aquifer System in the El-Marashda area, located beneath the Eastern Sahara Desert in northeastern Africa. The primary objective is identifying the aquifer geometry, assessing groundwater quality, and evaluating environmental pollution levels. A Magnetotelluric survey was employed to examine the subsurface geological composition and electrical resistivity characteristics of the aquifer system. The study revealed a freshwater-saturated Nubian Sandstone layer at depths between 986 and 1009 m with resistivity values of 101 to 182 Ohm.m, indicating a substantial and potentially sustainable groundwater resource. Overlying limestone and Marly Limestone layers influence the aquifer’s permeability and storage capacity. The chemical analysis of water from three wells showed suitability for drinking and irrigation, with no sodium and magnesium levels hazards. The Heavy Metal Pollution Index (HPI) and Heavy Metal Evaluation Index (HEI) indicated low to medium contamination, posing potential environmental health risks. Human health risk assessments using USEPA methodology found acceptable non-carcinogenic risks, with Hazard Quotients (HQs) for heavy metals below 1 and a negligible Hazard Index (HI). The comprehensive investigation underscores the potential for sustainable groundwater utilization in El-Marashda. It highlights the aquifer’s suitability for irrigation, with low contamination levels and minimal health risks. These findings provide a foundation for informed and sustainable water resource management, environmental protection, and resilient infrastructure development in the region. The methodologies and results align with global standards, demonstrating their applicability in globally diverse geological contexts. This research contributes valuable baseline data for future studies and monitoring efforts, whether at local or global sites, emphasizing the importance of continued investigation to ensure sustainable groundwater management.

Spatiotemporal analysis of compound droughts and heat waves in the Horn of Africa

AbstractClimate change has increased the frequency and severity of weather extremes, including droughts, heat waves and compound drought and heatwave (CDHW) events. CDHW events profoundly impact water availability, agriculture, public health and energy production, particularly in the Horn of Africa (HOA). This study examined the historical spatiotemporal patterns of CDHW periods in the HOA during three periods (1951–1980, 1971–2000 and 1991–2020) using the ERA5 reanalysis dataset. This study utilized monthly Standardized Precipitation Evapotranspiration Index (SPEI) data to detect droughts and daily maximum temperature data to identify heatwaves for characterizing the duration, severity and magnitude of CDHW events. The results show a substantial increase in the duration of CDHW events in recent years, with durations reaching up to 25 days. The average duration of heat waves also increased from 7 days before 1993 to 18 days by 2011, culminating in a record‐breaking 43‐day heat wave in 2019. Most areas experienced a significant increase in heatwave duration by more than 12 days from the early period of 1951–1980 to the late period of 1991–2020. Although around 76% and 69% of the HOA exhibited insignificant heatwave trends in the first two periods, Ethiopia and Kenya experienced substantial increases of more than 18 days during the most recent period, with some durations exceeding 25 days in recent decades. The magnitude of CDHW events generally decreased as drought duration intensified, but specific areas, particularly southwest Kenya and Eritrea, exhibited higher CDHW values in the last period. These findings underscore the urgent need to understand and address CDHW events in the HOA. Targeted interventions for disaster risk reduction and resilience‐building are needed to mitigate the adverse effects of these events in this vulnerable region. This study provides a basis for future research and policy formulation in the HOA.

Lineage-informative microhaplotypes for recurrence classification and spatio-temporal surveillance of Plasmodium vivax malaria parasites

Challenges in classifying recurrent Plasmodium vivax infections constrain surveillance of antimalarial efficacy and transmission. Recurrent infections may arise from activation of dormant liver stages (relapse), blood-stage treatment failure (recrudescence) or reinfection. Molecular inference of familial relatedness (identity-by-descent or IBD) can help resolve the probable origin of recurrences. As whole genome sequencing of P. vivax remains challenging, targeted genotyping methods are needed for scalability. We describe a P. vivax marker discovery framework to identify and select panels of microhaplotypes (multi-allelic markers within small, amplifiable segments of the genome) that can accurately capture IBD. We evaluate panels of 50–250 microhaplotypes discovered in a global set of 615 P. vivax genomes. A candidate global 100-microhaplotype panel exhibits high marker diversity in the Asia-Pacific, Latin America and horn of Africa (median HE = 0.70–0.81) and identifies 89% of the polyclonal infections detected with genome-wide datasets. Data simulations reveal lower error in estimating pairwise IBD using microhaplotypes relative to traditional biallelic SNP barcodes. The candidate global panel also exhibits high accuracy in predicting geographic origin and captures local infection outbreak and bottlenecking events. Our framework is open-source enabling customised microhaplotype discovery and selection, with potential for porting to other species or data resources.

Anti-Growth and Anti-Metastatic Potential of Raw and Thermally Treated Eragrostis tef Extract in Human Cancer Cells.

Teff (Eragrostis tef), a gluten-free cereal crop cultivated originally in Northeast Africa, is increasingly utilized due to its nutritional and health benefits. The aim of the present study was to investigate the effects of ethanol extract obtained from raw and thermally treated teff, referred to as RTE and TTE, respectively, on uncontrolled growth and activated metastasis using human cancer cell lines. Both RTE and TTE contained flavones, such as orientin (luteolin 8-C-glucoside) and vitexin (apigenin 8-C-glucoside), and phenolic acids, such as protocatechuic acid and p-coumaric acid. TTE showed higher total phenol, protocatechuic acid, and p-coumaric acid contents, but lower orientin content compared to RTE. RTE and TTE significantly suppressed cell growth of H1299 human lung cancer cells, with TTE exhibiting more pronounced effects than RTE, while both extracts had only minimal effects on the growth of non-malignant human umbilical vein endothelial cells. The growth-inhibitory activities of RTE and TTE in H1299 cells were associated with apoptosis induction and cell cycle arrest at the G2/M phase. TTE produced an additional effect on inducing cell cycle arrest at the S phase in H1299 cells, potentially contributing to its stronger growth-inhibitory effects. Moreover, both RTE and TTE effectively inhibited key events in metastasis, such as invasion, migration, and adhesion, in H1299 cells under non-cytotoxic conditions, with TTE showing stronger effects. In HCT116 human colon cancer cells, a similar pattern of inhibition was demonstrated against the metastatic events, accompanied by reduced levels of matrix metalloproteinase-2 and -9. Our results indicate that teff extracts exhibit in vitro anti-growth and anti-metastatic activities, which are enhanced by thermal treatment of teff.

Multidisciplinary Effort Leading to Effective Tuberculosis Community Outbreak Containment in Israel.

Tuberculosis (TB) is the second-most prevalent cause of mortality resulting from infectious diseases worldwide. It is caused by bacteria belonging to the Mycobacterium tuberculosis complex (MTBC). In Israel, TB incidence is low, acknowledged by the WHO as being in a pre-elimination phase. Most cases occur among immigrants from high TB incidence regions like the Horn of Africa and the former Soviet Union (FSU), with occasional outbreaks. The outbreak described in this report occurred between 2018 and 2024, increasing the incidence rate of TB in the region. Control of this outbreak posed challenges due to factors including a diverse population (including Ethiopian immigrants, Israeli-born citizens, and immigrants from other countries), economic and social barriers, and hesitancy to disclose information. The unique multidisciplinary team formed to address these challenges, involving the local TB clinic, district health ministry, health maintenance organization (HMO) infectious disease consultant, neighborhood clinic, and National Mycobacterium Reference Laboratory (NMRL), achieved effective treatment and containment. Whole genome sequencing (WGS) proved pivotal in unraveling patient connections during the outbreak. It pinpointed those patients overlooked in initial field investigations, established connections between patients across different health departments, and uncovered the existence of two distinct clusters with separate transmission chains within the same neighborhood. This study underscores collaborative efforts across sectors that successfully contained a challenging outbreak.

Predicting Food‐Security Crises in the Horn of Africa Using Machine Learning

AbstractIn this study, we present a machine‐learning model capable of predicting food insecurity in the Horn of Africa, which is one of the most vulnerable regions worldwide. The region has frequently been affected by severe droughts and food crises over the last several decades, which will likely increase in future. Therefore, exploring novel methods of increasing early warning capabilities is of vital importance to reducing food‐insecurity risk. We present a XGBoost machine‐learning model to predict food‐security crises up to 12 months in advance. We used >20 data sets and the FEWS IPC current‐situation estimates to train the machine‐learning model. Food‐security dynamics were captured effectively by the model up to 3 months in advance (R2 > 0.6). Specifically, we predicted 20% of crisis onsets in pastoral regions (n = 96) and 20%–50% of crisis onsets in agro‐pastoral regions (n = 22) with a 3‐month lead time. We also compared our 8‐month model predictions to the 8‐month food‐security outlooks produced by FEWS NET. Over a relatively short test period (2019–2022), results suggest the performance of our predictions is similar to FEWS NET for agro‐pastoral and pastoral regions. However, our model is clearly less skilled in predicting food security for crop‐farming regions than FEWS NET. With the well‐established FEWS NET outlooks as a basis, this study highlights the potential for integrating machine‐learning methods into operational systems like FEWS NET.

Climate change and migration dynamics in the Horn of Africa: a comprehensive review and future research directions

Introduction: In this study, relevant references are analysed to establish what factors determine migratory movements in the Horn of Africa and what role climate change plays. Methodology: A systematic literature review in five phases is conducted, selecting 221 relevant references based on inclusion and exclusion criteria. These references are used to analyze migration movements and the factors influencing them. Results: A notable increase in publications is highlighted since 2011, coinciding with a devastating drought in the region. Findings indicate that while climate change is an important factor, other elements such as poverty, insecurity, and conflicts play an even more significant role in regional migration. Discussion: Challenges, such as the lack of reliable data and the need for a multidisciplinary approach to address these complex issues, are identified. The region faces a critical situation with high levels of food insecurity, conflicts, and climate vulnerability, suggesting that climate change is an added factor to an already complicated situation. Conclusions: The study concludes that integrating climate change, migration, and conflicts in future research is crucial to develop effective and sustainable responses.

Apis florea in Europe: first report of the dwarf honey bee in Malta

ABSTRACTS The Red dwarf honey bee (Apis florea), is a single-comb open-nesting member of the genus Apis with a natural distribution area stretching from the Indomalayan realm on the east to the Persian Gulf on the west. However, it is reportedly colonising new territories mainly due to anthropogenic activities. Nowadays it can be found from Taiwan on the east, to Jordan, the Arabian Peninsula and North-eastern Africa on the west. Here we present the first scientific record of a fully established colony of A. florea in Europe. The colony was found on Malta, a crossway of naval routes in the Mediterranean Sea. We documented the incident with photos, collected samples of workers and drones and sequenced the mtDNA COI gene to confirm assignment to A. florea. Also, we alert the competent authorities and the beekeeping community to be vigilant and ready to undertake effective eradication measures. In the paper, we discuss the risks and the potential consequences associated with the invasion of A. florea in Europe.

Investigating the footprint of post-domestication dispersal on the diversity of modern European, African and Asian goats

BackgroundGoats were domesticated in the Fertile Crescent about 10,000 years before present (YBP) and subsequently spread across Eurasia and Africa. This dispersal is expected to generate a gradient of declining genetic diversity with increasing distance from the areas of early livestock management. Previous studies have reported the existence of such genetic cline in European goat populations, but they were based on a limited number of microsatellite markers. Here, we have analyzed data generated by the AdaptMap project and other studies. More specifically, we have used the geographic coordinates and estimates of the observed (Ho) and expected (He) heterozygosities of 1077 European, 1187 African and 617 Asian goats belonging to 38, 43 and 22 different breeds, respectively, to find out whether genetic diversity and distance to Ganj Dareh, a Neolithic settlement in western Iran for which evidence of an early management of domestic goats has been obtained, are significantly correlated.ResultsPrincipal component and ADMIXTURE analyses revealed an incomplete regional differentiation of European breeds, but two genetic clusters representing Northern Europe and the British-Irish Isles were remarkably differentiated from the remaining European populations. In African breeds, we observed five main clusters: (1) North Africa, (2) West Africa, (3) East Africa, (4) South Africa, and (5) Madagascar. Regarding Asian breeds, three well differentiated West Asian, South Asian and East Asian groups were observed. For European and Asian goats, no strong evidence of significant correlations between Ho and He and distance to Ganj Dareh was found. In contrast, in African breeds we detected a significant gradient of diversity, which decreased with distance to Ganj Dareh.ConclusionsThe detection of a genetic cline associated with distance to the Ganj Dareh in African but not in European or Asian goat breeds might reflect differences in the post-domestication dispersal process and subsequent migratory movements associated with the management of caprine populations from these three continents.

African Women in Neurosurgery: An Exploration of Historical Perspectives, Current Realities, and Future Prospects

Gender disparities remain a significant issue, particularly impacting African women in the field of neurosurgery. Databases, articles, and perspectives were reviewed to identify challenges faced by African Women in Neurosurgery (AWIN), and explore solutions for recruitment, retention, and career advancement of AWIN. In 1982, Africa saw its first female neurosurgeon, with the first female president of the World Federation of Neurosurgical Societies appointed 4 null decades later. Presently, the continent hosts 245 female neurosurgeons, with North Africa comprising the majority at 76.3%, with Algeria notably contributing 72.2% of this total. Southern Africa contributes 7.8%, while West Africa, East Africa, and Central Africa contribute 6.5%, 6.1%, and 3.3%, respectively. Thirteen countries lack neurosurgeons entirely and 30 out of the 54 African nations face shortages of female neurosurgeons, with distributions as follows: North Africa (1-country), Southern Africa (6-countries), West Africa (8-countries), East Africa (9-countries), and Central Africa (6-countries). Our analysis mapped the distribution of 245 AWIN across the African regions and examined the professional trajectories and achievements of 17 pioneering AWIN. Additionally, we compiled registries for: 1) 76 neurosurgical training programs across 26 African countries, 2) organizations tackling gender disparities in neurosurgery, and 3) recommendations to promote AWIN across governmental, community, and academic spheres. To boost AWIN representation in neurosurgery, concerted and comprehensive efforts are vital. Collaboration among medical schools, training programs, and governments is key to fostering diversity and inclusivity in African neurosurgical settings.

China’s economic boom and military advancement: realist perspective of the Dragon’s global power and presence in Africa

ABSTRACT Can and does realism explain the linkage between China’s economic advancement and its ever-increasing hard power and global influence? Realists assert that a growth in a nation’s economy triggers an upsurge in its craving for military or security advancement and power. Since the commencement of China’s ‘opening policy,’ its economy has witnessed tremendous hikes, being ranked second to the US economy. A vital coincidence of this is the ever-increasing attempt to modernising its military and general security systems. Of major concern is China’s recently established foreign military base in Djibouti in the ‘Horn of Africa.’ Realists have suggested that in such a Hobbesian world, Beijing will employ its economic power to assert its security interests. Analysing this linkage through a realist perspective, using case studies and historical analogies, the article concludes that realism best provides reasons for the phenomenon.

The stimulant cathine from Khat causes tachycardia indirectly in the rat.

Leaves of the Khat plant are widely consumed in the Horn of Africa, Yemen and the Jazan region of Saudi Arabia. I have investigated the mode of cardiovascular and autonomic actions of the stimulant cathine from Khat in terms of direct or indirect adrenergic actions in anaesthetised male and female rats, and in isolated tissues. Male and female rats were anaesthetised with pentobarbitone and changes in diastolic blood pressure and cardioaccelerator responses were examined in vehicle-treated or chemically sympathectomised rats. Cathine produced marked tachycardia and smaller blood pressure responses in vehicle-treated animals, with significant rises in heart rate occurring at cathine (0.1mg/kg). In sympathectomised rats, cardiac actions were greatly attenuated in both male and female animals, with no differences between male and female rats. Although pressor responses to cathine were relatively small, sympathectomy significantly reduced these responses in female, but not male, rats. In rat aorta and spleen, cathine produced almost no direct contractions. It is concluded that cathine acts predominantly indirectly, presumably by the release of noradrenaline, in both male and female rats to produce cardiovascular actions. This may have implications for adverse cardiovascular actions of consumption of the plant Khat, particularly with dried Khat, in which actions of cathine may predominate over those of cathinone.

The impact of forage condition on household food security in northern Kenya and southern Ethiopia

We studied the causal link between forage condition and food security in northern Kenya and southern Ethiopia and probed the mechanisms through which the effects occur. The study utilized weekly panel survey data collected over a period of 94 weeks (March 2021–December 2022) from drought-prone pastoral regions and estimated two-stage least squares instrumental variables regression to assess causal impacts. We found that an increase in the normalized difference vegetation index (NDVI) – our proxy for forage condition – by 10% significantly reduced the likelihood of a household experiencing food insecurity by 12 percentage points. The main mechanisms through which improved forage condition increased food security were livestock productivity enhancement, reduced prices of basic food commodities (cereals, legumes, and vegetables), and utilization of better coping strategies by households. These findings suggest the need for interventions and initiatives aimed at boosting livestock productivity and reducing vulnerability to drought-induced poor forage conditions. Efforts focused on the monitoring of forage conditions and supporting market development for livestock feed are important for addressing the adverse impacts of drought and deteriorating forage conditions in the horn of Africa. Furthermore, the monitoring of drought conditions and shocks using high-frequency data has the potential for providing early warning and informing anticipatory action.

HOW THE SOMALI MODERN GOVERNANCE WORKS WITH THE TRADITIONAL GOVERNANCE SYSTEM: LITERATURE REVIEW

Somalia, located in the Horn of Africa, has a complex history influenced by tribalism, colonialism, and internal conflict. During the colonial era, European powers collaborated with clan leaders, resulting in Somalia's division along clan and tribal lines. This division led to the creation of artificial borders, which fragmented the land and fostered regional and clan-based identities. After gaining independence in 1960, Somalia initially aimed to establish a strong, centralized state. The Siad Barre regime, which came to power through a military coup in 1969, tried to suppress clan and regional identities in favor of a communist ideology. However, the regime's downfall in 1991 plunged Somalia into a prolonged period of violence and state collapse. Warlords and clan-based factions fought for power, leading to a protracted civil war. This paper analyzes the intricate relationship between Somalia's traditional and modern governance systems. It examines the potential for collaboration, the challenges faced in nation-building efforts, and the lasting impact of clan-based structures. The study begins by exploring traditional governance, highlighting the important role of customary law, elders, and religious clerics in consensus-building mechanisms and maintaining social harmony. It emphasizes the historical significance and contemporary relevance of these institutions. The paper then delves into the challenges involved in establishing a modern state in Somalia. It examines the obstacles that hinder the realization of democratic ideals and the establishment of a centralized administration. A key focus is evaluating the potential synergies and conflicts between traditional and modern systems.

Unusually low dust activity in North Africa in June 2023: Causes, impacts and future projections

Dust activity during the pre-monsoon season in Africa has an impact on the monsoon circulation and the Atlantic hurricane season. During early June 2023 the atmosphere was relatively clear over West Africa and the eastern tropical Atlantic, in contrast with the dustier June 2020. The negative phase of the North Atlantic Oscillation suppressed dust lifting, with an equatorward shifted African Easterly Jet limiting its downstream advection. On the other hand, dust accumulated in the atmosphere over northeastern Africa, with the negative dust aerosol optical depth (DAOD) anomalies over western Africa and the positive anomalies over eastern Africa more than two standard deviations away from the climatological mean. The lack of dust led to an up to 55 W m−2 increase in the surface downward shortwave radiation flux and a 35 W m−2 decrease in the longwave flux, and is in line with the record-breaking sea surface temperatures over the eastern tropical Atlantic and the active start to the Atlantic hurricane season. In order to explore future projections of DAOD, a multi-model ensemble (MME) is constructed from 29 models that integrate the sixth phase of the Coupled Model Intercomparison Project (CMIP6). It captures the positive trend in the June DAOD over the eastern tropical Atlantic during 1980–2014, although the amplitude is roughly a factor of six smaller than the 0.0017 year−1 in the reanalysis dataset. The CMIP6 MME projects a further increase in DAOD in the region at a rate of up to 0.0003 year−1 in the most extreme climate change scenario for 2066–2100, which is comparable to that seen during the historical period, even though the mean values are projected to decrease by 0.03–0.06. While lower dust loadings may lead to improved air quality, they will likely further fuel pre-season and early season storms in the North Atlantic, which have become more frequent in recent decades.

The political economy of connectivity in the Somali Horn of Africa

Abstract This article focuses on the political economy of connectivity in the Somali Horn of Africa (HoA). On the one hand, it charts the emergence of firms in Somalia and Somaliland at the intersection of telecommunication and finance, eventually controlling logistics through digital platforms that enable the circulation of people, goods and value across the region. On the other, it examines the historical and political elements that have shaped a peculiar instance of digital capitalism against a backdrop of protracted insecurity and state fragility. It uses the specific case-study of digital platforms in the Somali HoA to provide insights into the multiple shapes that digital capitalism can take. To advance the authors' analysis, the article links the notions of digital infrastructural power and ‘extrastatecraft’. Empirically, it delves into the case of digital platforms in the Somali HoA to illustrate how the unique digital landscape of the region has evolved over fifty years of political instability and economic volatility. Theoretically, the article navigates the implications of the state's heavy reliance on privately owned and managed platforms amid the backdrop of variegated digital capitalism narratives, which have predominantly centred on the global North.

The one-humped camel: The animal of future, potential alternative red meat, technological suitability and future perspectives

The 2020 world population data sheet indicates that world population is projected to increase from 7.8 billion in 2020 to 9.9 billion by 2050 (Increase of more than 25%). Due to the expected growth in human population, the demand for meats that could improve health status and provide therapeutic benefits is also projected to rise. The dromedary also known as the Arabian camel, or one-humped camel (Camelus dromedarius), a pseudo ruminant adapted to arid climates, has physiological, biological and metabolic characteristics which give it a legendary reputation for surviving in the extreme conditions of desert environments considered restrictive for other ruminants. Camel meat is an ethnic food consumed across the arid regions of Middle East, North-East Africa, Australia and China. For these medicinal and nutritional benefits, camel meat can be a great option for sustainable meat worldwide supply. A considerable amount of literature has been published on technological aspects and quality properties of beef, lamb and pork but the information available on the technological aspects of the meat of the one humped camel is very limited. Camels are usually raised in less developed countries and their meat is as nutritionally good as any other traditional meat source. Its quality also depends on the breed, sex, age, breeding conditions and type of muscle consumed. A compilation of existing literature related to new technological advances in packaging, shelf-life and quality of camel meat has not been reviewed to the best of our knowledge. Therefore, this review attempts to explore the nutritional composition, health benefits of camel meat, as well as various technological and processing interventions to improve its quality and consumer acceptance. This review will be helpful for camel sector and highlight the potential for global marketability of camel meat and to generate value added products.

The role of regional water vapor dynamics in creating precipitation extremes

While sub-daily precipitation extremes cause flash flooding and pose risk to life, longer precipitation extremes threaten infrastructure such as water supply dams. Frequent storm or floods events replenish water supplies, ensuring the health of our ecosystems, while rarer larger storms or floods cause damage to property and life. These differing impacts depend on both storm rarity and duration and are largely dependent on coincident atmospheric water vapour. Using a novel metric that quantifies the extent of concurrency that exists between precipitation and total water vapour extremes, large regional variations are identified across the globe. Tropical regions such as Northeast Africa and South/East Asia consistently exhibit greater concurrency across all precipitation durations. In contrast, areas of the extra-tropics, such as the Mediterranean and Northwest Americas, show a rapid decline in concurrency with increasing duration. However, for rare events of long duration, non-tropical regions maintain high concurrency. With the link between climate change and increasing total water vapour well established, these results suggest that flood events will increase globally, with increases most apparent for longer and rarer events. This work underscores the need for tailored regional strategies in managing extreme precipitation and flood events in the future.

Estimating crop coefficients and water use of a full-bearing mango orchard in north-eastern South Africa using the fraction of vegetation cover and a dual source evapotranspiration model

In semi-arid countries like South Africa, commercially produced mango (Mangifera Indica L.) are grown entirely under irrigation. However, there is little accurate quantitative information on the water use of mango orchards, and few accurate water use models currently exist. In this study, we evaluated the performance of the FAO 56 method of estimating crop evapotranspiration (ETc) and a dual source water use model against measurements of actual consumptive water use of a commercial mango orchard. The FAO approach calculates ETc as the product of a crop coefficient (Kc) and the reference evapotranspiration (ETo). We derived Kc for well-watered orchards from readily available data including the fraction of vegetation cover, average tree height, and a stomatal control coefficient. The dual-source model calculated orchard evapotranspiration as the sum of tree transpiration and orchard floor evaporation derived from the modified Shuttleworth and Wallace model. Actual evapotranspiration was measured using an open path eddy covariance system, while tree transpiration was measured using the heat ratio method of monitoring sap flow. Data were collected in a mature ‘Tommy Atkins’ mango orchard grown with micro-sprinkler irrigation in north-eastern South Africa. Results show that the reference evapotranspiration explained most of the variation in orchard transpiration (R2 ∼ 0.78) compared to the solar radiation (R2 ∼ 0.66) and the vapour pressure deficit of the air (R2 ∼ 0.66). Compared with field measured water use data, the FAO method gave relatively accurate estimates of transpiration (R2 = 0.74, NRMSE = ±18.00 %, NMAE = ±15.00 %, NSE = 0.70) and evapotranspiration (R2 = 0.58, NRMSE = ±19.00 %, NMAE = ±16.00 %, NSE = 0.55). NSE is the Nash-Sutcliffe Efficiency. The dual-source model yielded slightly less accurate estimates of transpiration (R2 = 0.61, NRMSE = ±22.00 %, NMAE = ±20.00 %, NSE = 0.39) and evapotranspiration (R2 = 0.52, NRMSE = ±23.00 %, NMAE = ±25.00 %, NSE = 0.51). The basal crop coefficient (Kcb) showed small seasonal fluctuations, varying between 0.40 and 0.60 throughout the year. In contrast, Kc showed clear seasonality varying between 0.59–0.64 at flowering and fruit set and rising to 0.81–0.90 during the fruit growing phase. Estimates of the annual total transpiration (686 mm) from the FAO method were within 5 % of the actual measured values (677 mm) while the dual source model estimated 612 mm of transpiration, which was almost 10 % lower than the measured values. The results highlight that even though the FAO method requires fewer input parameters, it is potentially more accurate in estimating water use in mango orchards than the dual-source model.