A study of rainfall trends and temporal variations within seven sub-basins of Uganda spanning from 1940 to 2009 has been made. Rainfall climatologies are constructed from observational data, using 36 station records which reflect hydroclimatic conditions. Long-term changes in rainfall characteristics were determined by non-parametric tests (Mann-Kendall and Sen's T tests), coefficient of variation (CV), precipitation concentration index and drought severity index. Magnitude of change was estimated by applying Sen's estimator of slope. Decadal variability of rainfall with marked seasonal cycles is evident. Temporal variability of drought patterns is detected. Variations in annual rainfall are low with no significant trends observed in the main drainage sub-basins. Significant trends occur in October, November, December and January. A noticeable decrease in the annual total rainfall was observed mostly in northwestern and southwestern sub-basins. Rainfall trend in the second normal of June-July-August (JJA) was decreasing in all the main drainage sub-basins.Key words trend analysis; Mann-Kendall; Sen's T test; precipitation concentration index; drought severity index; drainage sub-basins; Uganda La nature des précipitations dans les principaux sous-bassins de l'Ouganda Résumé Une étude des tendances et des variations temporelles des précipitations dans sept sous-bassins de l'Ouganda à été réalisée sur lapériode allant de 1940 à 2009. La climatologie des précipitations a été construite à partir des données observées dans 36 stations représentatives des conditions hydroclimatiques. Les changements à long terme des caractéristiques des précipitations, coefficient de variation, indice de concentration des précipitations et indice de gravité de la sécheresse, ont été déterminés par des tests non paramétriques (test de Mann-Kendall et test T de Sen). L'amplitude du changement a été estimée en appliquant l'estimateur de pente de Sen. La variabilité décennale des précipitations aux cycles saisonniers marqués est évidente. La variabilité temporelle des phénomènes de sécheresse a été détectée. Les variations des précipitations annuelles sont faibles sans tendances significatives observées dans les principaux sous-bassins. Des tendances significatives ont été observées en octobre, novembre, décembre et janvier. Une diminution notable des précipitations totales annuelles a été observée principalement dans les sous bassins du Nord-ouest et du Sud-ouest. Une tendance à la décroissance des précipitations en juin-juillet-août (JJA) a été observée dans tous les sous-bassins principaux.

Infectious and zoonotic disease outbreaks have been linked to increasing volumes of legal and illegal trade. Spatio-temporal and trade network analyses have been used to evaluate the risks associated with these challenges elsewhere, but few details are available for the pig sector in South Africa. Regarding pig diseases, Limpopo province is important as the greater part of the province falls within the African swine fever control area. Emerging small-scale pig farmers in Limpopo perceived pig production as an important means of improving their livelihood and an alternative investment. They engage in trading and marketing their products with a potential risk to animal health, because the preferred markets often facilitate potential long-distance spread and disease dispersal over broad geographic areas. In this study, we explored the interconnectedness of smallholder pig farmers in Limpopo, determined the weaknesses and critical control points, and projected interventions that policy makers can implement to reduce the risks to pig health. The geo-coordinates of surveyed farms were used to draw maps, links and networks. Predictive risks to pigs were determined through the analyses of trade networks, and the relationship to previous outbreaks of African swine fever was postulated. Auction points were identified as high-risk areas for the spread of animal diseases. Veterinary authorities should prioritise focused surveillance and diagnostic efforts in Limpopo. Early disease detection and prompt eradication should be targeted and messages promoting enhanced biosecurity to smallholder farmers are advocated. The system may also benefit from the restructuring of marketing and auction networks. Since geographic factors and networks can rapidly facilitate pig disease dispersal over large areas, a multi-disciplinary approach to understanding the complexities that exist around the animal disease epidemiology becomes mandatory.

HOW TO CITE:Rautenbach V, Bevis Y, Coetzee S, Combrinck C. Evaluating procedural modelling for 3D models of informal settlements in urban design activities. S Afr J Sci. 2015;111(11/12), Art. #2015-0100, 10 pages. http://dx.doi.org/10.17159/ sajs.2015/20150100Three-dimensional (3D) modelling and visualisation is one of the fastest growing application fields in geographic information science. 3D city models are being researched extensively for a variety of purposes and in various domains, including urban design, disaster management, education and computer gaming. These models typically depict urban business districts (downtown) or suburban residential areas. Despite informal settlements being a prevailing feature of many cities in developing countries, 3D models of informal settlements are virtually non-existent. 3D models of informal settlements could be useful in various ways, e.g. to gather information about the current environment in the informal settlements, to design upgrades, to communicate these and to educate inhabitants about environmental challenges. In this article, we described the development of a 3D model of the Slovo Park informal settlement in the City of Johannesburg Metropolitan Municipality, South Africa. Instead of using time-consuming traditional manual methods, we followed the procedural modelling technique. Visualisation characteristics of 3D models of informal settlements were described and the importance of each characteristic in urban design activities for informal settlement upgrades was assessed. Next, the visualisation characteristics of the Slovo Park model were evaluated. The results of the evaluation showed that the 3D model produced by the procedural modelling technique is suitable for urban design activities in informal settlements. The visualisation characteristics and their assessment are also useful as guidelines for developing 3D models of informal settlements. In future, we plan to empirically test the use of such 3D models in urban design projects in informal settlements.

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