Effect of Canyon Geometry and Ground Conditions on the Seismic Performance of Tendaho Earthfill Dam in Ethiopia.

The seismic performance of earth dams is usually studied by two dimensional (2D) space. However, considerable judgment is required to estimate the overall three dimensional dynamic response of dams in a narrow canyon from plane strain analyses of individual sections of the dam. This is so because the plane strain analysis normally ignores the arching effect of the valley which is particularly relevant for dams in narrow valleys. Because of the arching action, the effect of the canyon geometry on the dynamic response of earth dams will be a stiffening of the system. The effect of the canyon geometry is studied by carrying out 3D model of a dam site using a finite difference code, FLAC3D. The assumed 3D model contains all details of the dam body and foundation materials but with variable valley configuration of Tendaho earthfill dam. The mentioned dam is an earth fill dam located in the Afar regional state of Ethiopia. The area is a seismically active area as it lies on the East African Rift valley which can generate earthquake of magnitude greater than 6. In addition, the alluvium foundation of the dam consists of granular materials, which may liquefy during strong earthquakes. In this paper, the numerical results for the different 3D simulations are compared and correlated. Moreover, the seismic performance of the Tendaho earth fill dam is investigated. From the results of the analyses and correlations created, the canyon geometry under which three dimensional behavior is of importance in the dynamic response of a dam are determined. And the resulting correlation is then applied to the Tendaho earthfill dam

Concurrent Infection of Hydatidosis and Fasciolosis in Cattle Slaughtered at Mekelle Municipal Abattoir, Tigray Region

An abattoir survey was carried out in Mekelle municipal abattoir, Ethiopia to determine the prevalence of concurrent infections of hydatidosis and fasciolosis in cattle. A total of 4,481 slaughtered cattle were studied by ante- and post-mortem examinations. From the total 4,481 slaughtered cattle examined at Mekelle municipality abattoir, 357 (8%) were found to harbor mixed infection of hydatidosis and fasciolosis. While the individual prevalence of hydatidosis and fasciolosis was 32.11% and 24.32%, respectively. Multivariate logistic regression analysis indicated that among the factors considered in the current study, origin of animals had statistically significant ffect on the prevalence of concurrent infection (OR = 1.418, 95% CI = 1.108 - 1.814, p = 0.005), whereas breed and body condition of animals didn’t have significant effect on prevalence of the co-infection. Moreover, month had no statistically significant effect on prevalence of hydatidosis and fasciolosis co-infection (OR= 1.0029, 95% CI = 0.9758 - 1.0306, p = 0.867). Generally this study showed that hydatidosis and fasciolosis are important disease problems in cattle in the study area. The relatively higher prevalence in the occurrence of the concurrent infection of hydatidosis and fasciolosis in this study may suggest that ecological factors that determine the occurrence of the two diseases might be similar. On the other hand, the higher prevalence of the individual or concurrent infection may imply that these diseases have the potential to cause considerable economic and public health problems. Keywords: Coinfection, Fasciolosis, Hydatidosis, Mekelle, Prevalence

Commercialization of vegetable production in Alamata Woreda, Northern Ethiopia: processes and impact

The Raya valley in Tigray where Alamata Woreda is located, has fertile soil, suitable climate and rich water resources to grow various crops including vegetables. Surface water from seasonal rivers/streams and small dams and ground water extracted from deep and shallow wells with various water lifting devices are the two main sources of water for irrigation in the Woreda. A participatory rural appraisal (PRA) study conducted by the Woreda stakeholders and facilitated by IPMS identified (irrigated) vegetables as a potential marketable commodity in 2005. Using the commodity value chain approach, production, input supply and marketing problems and opportunities were identified. Major problems were lack of interest partly as a result of market failure in the past, lack of agronomic and irrigation knowledge and skills resulting in lack of use of advanced agronomic inputs (e.g. seeds) and underutilization of modern irrigation facilitates (most of the deep wells established were not used and/or underutilized). Different extension approaches were used including study tours to change the mind-set and to acquire knowledge for experts and farmers. Following various production interventions, market linkages were created which resulted in better prices (from 0.70Birr/kg before 2005 to 3-5Birr/kg in the following years). Farmer to farmer communications, trainings, workshops and media coverage facilitated the further dissemination of knowledge and skills between PAs in Alamata and neighboring Woredas. As a result of these interventions, the area of irrigated onion, pepper and tomato tripled in size from 351 ha in 2004/05 to 1113 ha in 2008/09. The lion share of this increase was due to a ten fold increase in onion area from 84 ha in 2004/05 to 824 ha in 2008/09. Most of this increase took place in the spate irrigated areas where plots previously used for cereal crops (sorghum and teff) were converted to vegetables. Both women and men farmers benefited from the intervention. Many farmers managed to construct houses in town and were able to own different assets. The further expansion of the (irrigated) vegetable production in Alamata is feasible. However, more attention needs to be paid to improving productivity, especially in the spate irrigated areas since no clear evidence was found that area increase was accompanied by productivity increase, indicating lack of adequate institutional and farmers’ knowledge and skills. Also adverse weather conditions during the 2008 harvesting season, resulted in considerable crop spoilage and lower prices – indicating the risk associated with this commodity under rain-fed conditions. Finally, potential salinity problems should also be taken into account

Changes in response to integrated interventions in the value chain of vegetables in Atsbi-Womberta District of Tigray Region, Northern Ethiopia

With irrigated vegetables development, interventions on the uses of improved inputs such as water lifting devices; varieties; on-farm water, nutrient and pest management, and access to credit and market information were introduced in Atsbi-Womberta district, Ethiopia. Besides, skill and uptake capacity of vegetable growers, extension service providers and vegetable traders were improved accordingly. The response to the integrated interventions in the valuechain of vegetables indicated that the total annual income increased from less than 16,733 in 2000 to more than 3.0 million USD in 2008. Simultaneously, beneficiaries increased by 82% while irrigated vegetable coverage by 87%. These successful changes in income attributed to improved capacity of actors to manage irrigated vegetables effectively in response to emerging opportunities and challenges including shifts in irrigated crop choices in reply to nutrient mining, pest load and market demand. Hence, the introduction of highland pulses in rotation with vegetable successfully breaks the pest load and increase soil fertility while simultaneously generating high income. Moreover, the presence of attractive market for vegetables and alternative crops triggers the expansion of water harvesting and utilization, increased crop diversification and sharpened the choice of marketable crops to optimize income

Decomposition of the Kenticha mangano-tantalite ore by HF/H2SO4 and KOH fusion

In this study, the decomposition behavior of Ta and Nb from the mangano-tantalite ore was investigated using HF/H2SO4 mixture and KOH fusion. The effects of reaction time, decomposition temperature, acid and alkaline concentrations, and particle size on the dissolution process were examined. Higher decomposition rates were achieved at 6:2 mol/dm3 ratio of HF and H2SO4, and with the addition of 10 g KOH in the alkali fusion step. In addition, similar trends in decomposition rates between two agents (HF/H2SO4 and KOH) and comparable dissolution performances were observed. The increase in the decomposition temperature initially increased the decomposition rate of manganotantalite for the two systems considered in this study. However, no significant change in the leaching rate of Ta and Nb was observed beyond 50 °C for the HF/H2SO4 system and above 400 °C when using the KOH fusion process. The elemental and compositional analyses of the leached residues using XRF, XRD, and FT-IR spectroscopy indicated that the acid (mixture of HF and H2SO4) decomposition resulted in slightly better dissolution performance for Ta compared with the alkaline fusion method. Overall, the results indicated that KOH can be a suitable alternative decompositi

Shifting towards market-oriented irrigated crops development as an approach to improve the income of farmers: Evidence from northern Ethiopia

Rainfed crop production in the semi-arid areas is associated with high risk of rainfall variability which occasionally leads to complete crop failure. Most of the farmers in Atsbi-Womberta district of Eastern Tigray region, northern Ethiopia, have been classified as food insecure. To improve farmers’ livelihoods in the district, interventions targeted at resource conservation and better use of conserved water for market-oriented irrigated crops development have been promoted. This paper analyses the process and outcome of shifting towards market-oriented irrigated crops development and compares variation in income between beneficiary and nonbeneficiary households. The transformation processes are based on market-oriented diversification into high value irrigated crops, based on a value chain approach, and demand driven, participatory and knowledge based extension. The paper also assesses the response of smallholder farmers to emerging opportunities and challenges, and the spectrum of transformation processes and strategies followed to bring changes in smallholder farmers’ income. The changes associated with the interventions were systematically captured using household level surveys, specialized studies and key informant interviews. Results show that farmers gradually shifted to non-cereal, more market-oriented irrigated crops, in which the share of market-oriented irrigated crops increased from 27% of the total irrigated land in 2004 to 89% in 2009. Similarly, the total irrigated area increased by about fourfold and the number of beneficiaries by about threefold due to improved use of conserved surface and groundwater, and investment in farmer skills and water lifting devices. Moreover, crop diversification and intensification of households increased in response to emerging opportunities and challenges. Annual cropping intensity shifted from mono-crop cereal to 2–3 high value diversified crop farming by some farmers. On aggregate, average income of beneficiary households increased by about ninefold compared to non-beneficiary households. In the transformation, there have been continuous and interconnected processes and strategies in improving the effectiveness of adopting and using new skills and knowledge in harvesting and productive use of water, and responsive capacity of the extension system and partners. The lessons imply that investment in resources conservation could be enhanced if linked with short-term income generating activities through linkages with markets