1,720,956 research outputs found
Climate change implications on water availability and crop production: Exploring adaptation strategies in the Olifants River basin, South Africa
No full textThesis PhD (Environment and Society))--University of Pretoria, 2021.Climate change is expected to have direct and indirect impacts on water resources and agricultural production systems, which potentially threatens the livelihood of local, regional and global population as well as the economy. The level and trend of the impact caused by climate change is dependent on the specific location and adaptive capacity of local communities and food producers.
The main aim of this thesis was to evaluate the impact of climate change on water availability and crop production as well as to assess the extent to which adaptation strategies can mitigate the impact in the Olifants catchment, South Africa. To achieve the stated aim of this study, three research objectives were analysed.
- The first objective evaluated the impact of climate change on water availability and assessed the extent to which a range of adaptation measures can mitigate the impact.
- The second objective investigated smallholder farmers’ perception of climate change and their adaptive responses using a questionnaire-based interview.
- While the third objective quantified the impact of climate change on crop production and evaluated possible agricultural management practices adopted by farmers to improve current and future crop yield using a processed-based crop model. This model was driven by high resolution climate change simulations for current conditions (1975-2006) as well as future climate projections (2010-2039), (2040-2069) and (2070-2099) for representative Concentration Pathways (RCPs), RCP4.5 and RCP8.5.
The findings of the first objective revealed that climate change is expected to cause an increase in temperature of 1℃ to 4℃, with precipitation decreasing by 5% to 30% for both RCP4.5 and RCP8.5 respectively. Results further revealed that water demand will not be met in the future due to increasing socio-economic development, coupled with decreasing streamflow resulting from increased temperature and decreased precipitation. In addition, results from the assessment of adaptation strategies indicated that the combination of management strategies provided a better and more efficient solution to water scarcity issues arising from climate change.
The findings of the second objective showed that about 98% of smallholder farmers were aware of climate change. Their perception of these changes aligns with actual meteorological data of decreasing inter-annual rainfall and an increasing temperature trend. Results also revealed that 90% of smallholder farmers adopted several adaptation measures, among which, the use of improved seed varieties, application of chemical fertilizer, and changing planting dates, were the most commonly practised.
Finally, the findings of the third objective revealed an increase in crop water requirement and a decline in crop yield, ranging between 19-65%, 11-38%, 16-42% and 5-30% for maize, soya beans, dry beans, and sunflower, under both RCPs climate change scenarios. The decline in crop yield was attributed to the increase in temperature accompanied by a decrease in precipitation. Among the various agricultural management practices (shifting of planting date with the application of full irrigation, use of irrigation efficiency techniques, application of deficit irrigation water, and the use of rainwater harvest) were evaluated to minimize the negative impacts of climate change, the integration of altering the planting date with the application of full irrigation as well as the use of rainwater harvest was found to be more effective in improving crop yield under the impact of climate change. The overall findings of this study provide insight to policy makers on the most appropriate strategies to be implemented in order to ensure future water resources and crop production in the context of climate change.National Research Foundation-The World Academy of Science (NRF-TWAS)University of Pretoria Postgraduate BursaryGeography, Geoinformatics and MeteorologyPhD (Environment and Society)Unrestricte
Impact of climate change on crop production and potential adaptive measures in the Olifants catchment, South Africa
Get PDFClimate change is expected to substantially reduce future crop yields in South Africa, thus
affecting food security and livelihood. Adaptation strategies need to be implemented to mitigate the
effect of climate change-induced yield losses. In this paper, we used the WEAP-MABIA model, driven
by six CORDEX climate change data for representative concentration pathways (RCPs) 4.5 and 8.5, to
quantify the effect of climate change on several key crops, namely maize, soya beans, dry beans, and
sunflower, in the Olifants catchment. The study further investigated climate change adaptation such
as the effects of changing planting dates with the application of full irrigation, rainwater harvesting,
deficit irrigation method, and the application of efficient irrigation devices on reducing the impact of
climate change on crop production. The results show that average monthly temperature is expected to
increase by 1 ◦C to 5 ◦C while a reduction in precipitation ranging between 2.5% to 58.7% is projected
for both RCP 4.5 and RCP 8.5 relative to the baseline climate for 1976–2005, respectively. The results
also reveal that increased temperature and decreased precipitation during planting seasons are
expected to increase crop water requirements. A steady decline in crop yield ranging between
19–65%, 11–38%, 16–42%, and 5–30% for maize, soya beans, dry beans, and sunflower, respectively,
is also projected under both RCPs climate change scenarios. The study concludes that adaptation
measures such as the integration of changing planting dates with full irrigation application and the
use of rainwater harvest will help improve current and future crop production under the impact of
climate change.The Nation Research foundation-The World Academy of Science (NRF-TWAS)http://www.mdpi.com/journal/climatepm2021Geography, Geoinformatics and Meteorolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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