Browsing Research articles (Dept of Chemistry) by Subject "Botswana"
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Jain, P.K.; Lungu, E.M.; Prakash, J. (Elsevier Science Ltd. www.elsevier.com/locate/renene, NaN, 2003)[more][less]
Abstract: The Republic of Botswana is one of the sunniest countries in Southern Africa. It has very little cloud cover, insufficient rainfall, very low humidity, and very low wind speed throughout the year for most parts of the country. The daily extremum temperatures appear to be very much related to solar irradiation which in turn depends on sunshine duration. In Botswana, solar irradiation on a horizontal surface is measured only at Sebele, but sunshine duration and extremum temperatures are measured at several locations throughout the country. This paper presents bivariate models that relate solar irradiation to sunshine duration, and solar irradiation to extremum temperatures for Sebele, Botswana. Autocorrelation analysis revealed that the solar irradiation series is stationary for d=2 and D=0, sunshine duration series is stationary for d=0 and D=0, while the extremum temperatures series are stationary for either d=0 and D=N where N=1, 2, . . . or d=1 and D=1. It is found that there is a lag of three months between the peaks of the differenced series of fractional sunshine duration and fractional solar irradiation. On the other hand it is found that there is at most a lag of one month between the peaks of the differenced series of maximum temperature and solar irradiation, and that there is no lag between the peaks of the differenced series of minimum temperature and solar irradiation. Analysis of the noise component revealed that the bivariate processes under consideration behaved either as a purely seasonal MA processes of order (0,1,1) or as ARIMA processes of order (0, 1, 1)x (0, 1, 1)12 or as a purely nonseasonal, autoregressive process of order 2. We claim that the relationships found for Sebele can be applied to estimate solar irradiation at other locations with climatic conditions similar to Botswana. URI: http://hdl.handle.net/10311/177 Files in this item: 2
jain_RE_2003.pdf (1.288Mb)license.txt (1.998Kb) -
Mubyana-John, T.; Wutor, V.C.; Yeboah, S.O.; Ringrose, S. (Academic Journals. http://www.academicjournals.org/SRE, NaN, 2007)[more][less]
Abstract: The influence of wild fires on microbial community structure, soil organic matter, sulphur oxidising and nitrifying microbial populations in the floodplains of the Okavango Delta of Botswana was assessed. Microbial community structure was assessed by phospholipids ester-linked fatty acids (PLFA) quantification while microbial sulphur oxidisers were assessed by Most Probable Number (MPN). Community structure assessment showed that burning shifted the microbial community structure from single cellular bacteria being the dominant groups to filamentous fungi and actinomycetes being the most dominant groups. Generally burning increased the fungal component (18:2 w6) matrix from 3.40 to 8.35 while the actinomycetes and sulphur reducing bacterial (10 Me 16:0) component also increased from 1.02 to 1.70 mostly in the floodplains. Generally, the organic matter content declined with burning. However, the influence of burning on soil pH was non conclusive. Soil microbial biomass carbon increased slightly after the fire. The number of heterotrophic and nitrite-oxidizing and sulphur reducing bacteria increased. Overall, these results indicate that burning significantly alters the microbial community structure as large above ground losses of nutrients during and after burning often results in low quantities of nutrients released into the soil. URI: http://hdl.handle.net/10311/349 Files in this item: 1
Fire and.pdf (2.461Mb) -
Alemaw, B.F.; Chaoka, T.R.; Totolo, O. (Elsevier Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/413/description#description, NaN, 2006)[more][less]
Abstract: The agricultural economic sector of Botswana is limited mainly to range resources-based livestock and pockets of arable farming based on rainfall and limited irrigated agriculture at several places. In this study agricultural sustainability of rain-fed agriculture is investigated in Botswana by considering the Pandamatenga plains as a case study. Daily soil moisture regimes with respect to crop growth cycle were modelled using a water balance model based on 42 years of daily hydroclimatic inputs and corresponding simulated components of soil moisture, evaporation, surface runoff, and deep percolation. Using a sustainability criterion on crop water requirement and soil moisture availability during the cropping periods, it was found that rain-fed agriculture of maize, sunflower, and sorghum crops is sustainable. The relative sensitivity to drought of these crops was also found to conform to the Agromisa recommendations. In the pursuit to explore more IWRM opportunities, through the simulation of the corresponding direct runoff, we have also explored that more water harvesting opportunities exist in order to manage rainfall excesses effectively. URI: http://hdl.handle.net/10311/155 Files in this item: 4
alemaw_chaoka_totolo_06.pdf (2.112Mb)license.txt (1.998Kb)license.txt (1.998Kb)license.txt (1.998Kb)
Now showing items 1-3 of 3