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Search Results: 1 - 10 of 53021 matches for " David Chikodzi "
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Crop Yield Sensitivity to Climatic Variability as the Basis for Creating Climate Resilient Agriculture  [PDF]
David Chikodzi
American Journal of Climate Change (AJCC) , 2016, DOI: 10.4236/ajcc.2016.51008
Abstract: Climate change and variability are presenting challenges to the agricultural sector as well as agricultural sustainability in Zimbabwe. This paper was aimed at investigating the impacts of climate change and variability on maize, sorghum and groundnut production in the Buhera district of Zimbabwe. The paper specifically determined the climatic scenarios in Buhera and how crop production is sensitive to them. Temperature and rainfall data used were obtained from the Zimbabwe Meteorological Services Department. Crop yield data for maize, sorghum and groundnuts were obtained from the Department of Agriculture and Rural Extension Buhera District office. The Mann-Kendall Trend test was then used to determine if there were significant changes in the precipitation and temperature scenarios at Buhera weather station. Before performing the Mann-Kendall test, the time series data were first tested for auto-correlation. Finally the Spearman’s correlation coefficient was used to determine how precipitation and crop yields were related and the strength of their relationships. Mann-Kendall trend tests reviewed that only mean minimum temperatures show significant trends over time (p = 0.003, α = 0.05). Correlation analysis showed that only maize showed a significant correlation coefficient with the amount of rainfall (r = 0.79, r2 = 0.625 and p = 0.001, α = 0.05). The research showed that groundnuts were the least sensitive to climatic variations followed by sorghum; hence their production offers the best climatic resilience and must be encouraged to local subsistence farmers.
An Assessment of Trends of Monthly Contributions to Seasonal Rainfall in South-Eastern Zimbabwe  [PDF]
Brain Mapurisa, David Chikodzi
American Journal of Climate Change (AJCC) , 2014, DOI: 10.4236/ajcc.2014.31005
Abstract:

Trends in the proportional contribution to the seasonal rainfall of each month were analyzed for the meteorological stations of Buffalo Range, Masvingo Airport and Zaka in South-Eastern Zimbabwe. Results found indicate the existence of some trends for all the stations and months. However, when subjected to a Mann-Kendel trend analysis, all the trends were found to be statistically not significant for all instances except for the month of October at the Zaka station. This month showed a significant trend of increasing proportional rainfall.

Using River Altitude Determined from a SRTM DEM to Estimate Groundwater Levels of the Tokwe and Mutirikwi Watersheds in Zimbabwe  [PDF]
David Chikodzi, Godfrey Mutowo
Journal of Geographic Information System (JGIS) , 2016, DOI: 10.4236/jgis.2016.81007
Abstract: Groundwater resources provide most of the domestic water supply in rural Zimbabwe and support poverty reduction through irrigation facilities. Most agricultural and environmental plans need water table depth analysis as an input in designing best management strategies. There are limited direct measurements of groundwater levels in Zimbabwe due to high costs and the limited human expertise. The study is aimed at coming up with a proof of concept that altitude of rivers as determined by an SRTM digital elevation model can be used to estimate the levels of groundwater in parts of Mutirikwi and Runde sub catchments of southern Zimbabwe. The study also maps the groundwater levels of the area as determined by river altitude from the digital elevation model. Firstly, the groundwater levels for nine boreholes are measured. Secondly, the altitude of a river bed nearest to each borehole site is extracted from a digital elevation model. Finally, the Spearman’s correlation coefficient is used to determine the nature and strength of the relationship between the two variables. Linear regression analysis was also used to obtain the predictive equation of the relationship and its coefficient of determination. After the relationship between groundwater and river altitude is established, 9 new random points of river altitude are generated across the study area interpolated using kriging interpolation to give the estimated altitude of river altitude. The altitude of groundwater is then determined by running the predictive equation Y = 0.8736 * X + 0.852 obtained from regression analysis. The depth to groundwater level of area is obtained by subtracting the determined groundwater altitude from the SRTM DEM. The results show strong positive and statistically significant (ρ= 0.000,α= 0.01) correlation coefficient of 0.971 between measured groundwater levels and altitude of rivers. The regression model shows a coefficient of determination (r2) of 0.975. The research therefore determines that altitude of rivers and use of geostatistics can
Climate Change and Variability in Southeast Zimbabwe: Scenarios and Societal Opportunities  [PDF]
David Chikodzi, Talent Murwendo, Farai Malvern Simba
American Journal of Climate Change (AJCC) , 2013, DOI: 10.4236/ajcc.2013.23A004
Abstract:

A lot of researches have been done on the negative impacts and challenges caused by extreme weather conditions due to climate change and variability. Not many researches have been focused on the positive side in form of opportunities presented due to climate change. The study aimed to show the climate change scenarios and explore possible opportunities that could be derived from such scenarios in the southeastern region of Zimbabwe. The research used climate data records from three Zimbabwe Meteorological Services Department run weather stations in the region. The time series data were analyzed to show trends of rainfall and temperature over time. A questionnaire survey was also carried out to enquire from the farmers if they perceived climate change to have any opportunities. The rainfall trend analysis showed that rainfall amounts have declined at two of the three stations used. Rainfall total was also shown to be variable from year to year at all the stations. Ambient temperatures at all the stations were shown to have increased for both winter and summer. Opportunities that could be derived from climate change in the region were identified as the hydrological, agricultural and industrial. The research concludes that taking advantages of opportunities offered by climate change and variability provides the quickest way of embracing climate change adaptation.

Biomonitoring of Mucheke and Shagashe Rivers in Masvingo, Zimbabwe Using Macro-Invertebrates as Indicators of Water Quality  [PDF]
David Chikodzi, Munamato Mabhegedhe, Tatenda Kudakwashe Tunha
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.59016
Abstract: The traditional way of assessing water quality of water bodies is through measurement of biological, physical and chemical parameters. However, such assessments only reflect the concentration of pollutants at the time of sampling not periodic pollution events. The goal of the study was to evaluate the river health using the macro-invertebrates that are found within the Mucheke and Shagashe rivers of Masvingo City as water quality monitors. The South African Scoring System (SASS 5) was used to score using the sensitivity of macro-invertebrates to levels of pollution in the two river systems. The data collection process was carried in April 2017 at four sampling sites using the kick sampling method and results validated by testing the physical, chemical and biological characteristics of the water and comparing them with the macro-invertebrates score. Results showed that the mean sensitivity score of macro-invertebrates showed variations depending on the selected site. Sample sites B2 and A2 downstream of the two river systems show high levels pollution tolerant macro-invertebrates as compared to sites A1 and B1 that are on the upper course and have more of pollution sensitive macro-invertebrates. On validation, to a large extent the levels of pollution indicated by macro-invertebrates were found to be congruent to the levels of pollution indicated by the physical, chemical and biological parameters. The research concludes that the presence of specific types of macro-invertebrates can be used to assess the levels of pollution in Mucheke and Shagashe rivers of Masvingo City.
The influence of the different elements of an organic molecule structure on the main kinetic parameters of its unimolecular reaction in the high-pressure region  [PDF]
David Krinkin
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.38090
Abstract: The most general dynamic tendencies of the energy redistribution in the high-pressure region are considered. Their influence on the possible deviations from the kinetic conceptions, which is now generally accepted, is examined. In this way, the structural elements of an organic molecule that promote internal energy mobilization in the high-pressure region and, conversely, hamper it, are defined. The first of these elements reduces both the Arrhenius parameters of the unimolecular reactions while the second leads to the opposite results. Some well-known exceptions to existing kinetic theories, which find an explanation in the framework of these proposed concepts, is considered. The proposed concept is very general as distinct from the existing dynamic studies, which investigate more particular details of the separate bond behaviors. The proposed general concept can broaden the study of chemical kinetics.
Raising Engagement and Enhancing Learning: School Community Partnerships That Work for Students at Promise  [PDF]
David Zyngier
Creative Education (CE) , 2011, DOI: 10.4236/ce.2011.24053
Abstract: This paper reports on a pilot study that investigates the widely reported issue of underachievement of students from Culturally Linguistically and Economically Diverse (CLED) backgrounds. It involves 15 university education faculty student volunteers and over 40 students and their families in primary (elementary) schools situated in disadvantaged communities of Victoria whose students come from 40 different nationalities, speaking 36 languages and with 75 per cent of its student cohort coming from Non English Speaking Backgrounds. A partnership was formed to focus on the problem of CLED children’s disengagement from their academic learning. We focus on how a productive partnership between schools and a university impact on inclusive teaching and learning practices both at the school and the university level. We investigate whether such an intervention can have an impact on engagement levels and the learning and social outcomes of students from refugee, migrant and working class families. Privileging participant voice we analyze data from interviews, surveys and focus groups with students, teachers and parents to argue that such a program has the capacity to re-engage underachieving students at a minimal cost to the community as an alternative model to other expensive and unsuccessful intervention programs. We conclude that at the core of this successful program is the need for both participants to feel they are empowered in the process. We know that student outcomes can be enhanced when the students feel connected to and involved in their community. Through this project, the students have the opportunity to experience greater community engagement leading to improved school attendance and retention, as well as better academic outcomes.
A Simple Proof That the Curl Defined as Circulation Density Is a Vector-Valued Function, and an Alternative Approach to Proving Stoke’s Theorem  [PDF]
David McKay
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.21007
Abstract: This article offers a simple but rigorous proof that the curl defined as a limit of circulation density is a vector-valued function with the standard Cartesian expression.
“Your Guide to Paediactric Anesthesia” by Sims and Johnson: A Book Review  [PDF]
David Faraoni
Open Journal of Anesthesiology (OJAnes) , 2012, DOI: 10.4236/ojanes.2012.21003
Abstract: “Your Guide to Paediatric Anaesthesia”by Sims and Johnson is the first edition of a book written for fellow or non-pediatric anesthetists. The authors give a practical approach for daily practice in pediatric anesthesia. This \"book review\" describes a general presentation and an objective evaluation of this recently published book.
On Choosing Fourier Transforms for Practical Geoscience Applications  [PDF]
David Boteler
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325096
Abstract: The variety of definitions of Fourier transforms can create confusion for practical applications. This paper examines the choice of formulas for Fourier transforms and determines the appropriate choices for geoscience applications. One set of Discrete Fourier Transforms can be defined that approximate Fourier integrals and provide transforms between sampled continuous functions in both domains. For applications involving transforms between a continuous function and a discrete function a second set of Discrete Fourier Transforms is needed with different scaling factors. Two classes of application are presented: those where either form of transforms can be used and those where it is necessary to use a particular transform to obtain the correct results.
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