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PhDRDV / Institute for Rural Development / Currently, there is limited understanding, appreciation and dissemination of indigenous raining making practices. Yet indigenous rain making is part of the rich African heritage. The current study was premised on the view that indigenous rain making practices can help combat the negative effects of climate change if properly integrated with western science. A mixture of exploratory and survey designs was adopted in this study, which sought to examine the common indigenous rainmaking practices in Chimanimani District of Zimbabwe prior to developing strategies for reducing the negative impacts of climate change on the livelihoods of rural households. Various studies with the following specific objectives were carried out: to analyze the general community perceptions on the potential of indigenous rain making practices in combating the negative effects of climate change; to examine the components of indigenous rainmaking practices; analyse the means of disseminating knowledge on indigenous rainmaking; to identify the negative effects of climate change on the livelihoods of rural households; to assess the effectiveness of existing strategies used by households to cope with the negative effects of climate change; and to propose strategies for utilizing indigenous rainmaking practices to counter the negative effects of climate change on the livelihoods of rural households. Semi-structured interview guides and a questionnaire requiring responses on a Likert-type scale were used to collect data. Key informants and ordinary community members were selected using judgmental, convenient and snowballing sampling techniques. The Thematic Content Analysis technique was used to draw meaning out of the qualitative data. Chi-Square tests for Goodness of Fit were conducted using the Statistical Package for Social Sciences (SPSS) to establish if there were significant relationships among perceptions. It was indicated that the shift in seasons as exemplified by the Nyamavhuvhu wind which now swept Chimanimani in September or October instead of end of July to August was evidence of climate change. Responses with respect to the negative effects of climate change included food insecurity, and drying up of streams and rivers. Availability of water for domestic, agricultural and animal use was becoming increasingly unreliable. The respondents argued that they believed in the effectiveness of indigenous rain making if it is conducted following local customs and traditions. Significant differences in the following perceptions were observed for “Besides makoto and Christian prayers there are other common rainmaking practices practiced in Chimanimani District” (p < 0.05). Similar results were observed with regard to “I believe indigenous and western knowledge of rainmaking can complement each other” (P < 0.001), and “There is increase in pests and plant diseases than before” (P < 0.01). Components of indigenous rain making v identified in the current study included rain making ceremonies (makoto), which entailed use of beer, sacrificial bird (normally a cock) and natural resources conservation such as keeping places for local rain making rituals sacred (zvitenguro), not destroying very big trees for example fig tree (muonde: Ficus capensis), mukute (Syzygium cordatum) and others, and treating forests as sacred. With respect to the negative effects of climate change, a highly significant difference was observed for duration of stay in relation to, “There is now a high risk in planting winter wheat due to changes in climate” (P < 0.01); “Wetlands are disappearing in our area” (P < 0.01); “There is general reduction in yields due to climate change” (P < 0.001) and “We are experiencing scarcity of water for domestic animals and for household use” (P < 0.05). Lastly, highly significant relationships between “Rivers are drying up in our area” and education (P < 0.01) and duration of stay (P < 0.001). Methods used to disseminate indigenous knowledge of rain making were said to be ineffective. Information was being passed on through oral means. It was indicated that better use of modern technology and social media, in particular radio, television, Twitter, WhatsApp and Facebook might enhance people’s knowledge on indigenous rain making. By so doing, the perception that indigenous rain making was merely history and not knowledge that can be used in people’s daily lives would be eliminated. Furthermore, current strategies utilized to combat the negative effects of climate change were reported to be unsustainable. Among these were reliance on harvesting wild fruits for sale and hunting. Human activities such as veld fires, deforestation and over harvesting of wildlife were viewed in negative light with respect to combating negative effects of climate change. It was proposed that communities should revert to respecting traditional beliefs of conserving forests. This said to be key in normalizing climate, attracting back the birds and animals that used to be key in weather forecasting. Replanting and indiscriminate cutting of trees along rivers as effective prevention of stream bank cultivation were proposed. Re-introduction of heavy fines by traditional leadership was suggested as a tried and tested strategy that was no longer being applied when implementing conservation initiatives. The observation made in this study that western science and indigenous rain making practices were similar in many respects, suggested that these were opportunities that could be used to anchor strategies for integrating them. In addition to this, the need for establishing collective deliberation or interface platforms coupled with continuous communication and careful management of intellectual property was obvious.

M.Sc. (Geography) / The 1982/1983 drought in the summer rainfall regions of South Africa highlighted the dependence of the agricultural sector as well as the general economy of the country on climatic vagaries. The results as indicated in this dissertation fonn a basis for the development of a yield prediction model for maize in the south-eastern Transvaal. The study consists of two parts, namely:- a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole. a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions: Various methods were investigated for this purpose and T-mode Principal Components Analysis with the subsequent clustering of component scores were found to be the most acceptable. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole: Various parameters such as rainfall amount~ number of rain-days~ rainfall intensity~ seasonality and variability of rainfall were analysed. The presence of rainfall cycles and absence of linear trends were established. The orographic effect of the Eastern Escarpment on the spatial distribution of rainfall amount, frequency and intensity is clearly shown. Areas where conditions are less suitable for the dry-land cultivation of crops due to factors such as rainfall variability (in excess of 30%), steep slopes and relatively low rainfall intensity, were identified. Significant correlations were found between spring and late summer rainfall of a dry year

Tree population dynamics were monitored in three tropical rain forest sites in Peninsular Malaysia. The studies involved trees ≥ 10 cm dbh, over 36 years in hill dipterocarp forest at Bukit Lagong, and over 38 and 13 years in lowland dipterocarp forests at Sungei Menyala and Pasoh respectively. Trees were periodically measured for dbh, and mortality and recruitment recorded. Sapling populations at Sungei Menyala were also enumerated at periods separated by about 30 years. The major findings were: decline in tree density over the periods of study were offset by incremental growth in surviving trees, showing that the forests are fully stocked and structurally stable; mortality rates and 'half-life' values were 2.03%, 2.07% and 1.39% yr^-1, and 34.2, 33.5 and 49.9 years for Sungei Menyala, Pasoh and Bukit Lagong respectively; mortality was not correlated with size class for the lowland forests, but there was some evidence for higher mortality in the larger size classes for the hill forest, this possibly being related to soil instability on steep slopes; the risk of death was about 7-8 times greater for trees with negative or no growth, with suppression leading to higher mortality in canopy than in understorey species; recruitment rates to the 10 cm dbh class were 1.32%, 1.46% and 0.85% yr^-1 at Sungei Menyala, Pasoh and Bukit Lagong respectively; dbh increments were linear over long periods for most trees, future size of individuals therefore predictable from one set of measurements; fast-growing mature trees are estimated to be as young as 60 years; variation in species composition over time was slight compared with variation between sites; sapling composition and density at Sungei Menyala changed greatly over 30 years but that for adults remained constant over 38 years, showing that future canopy composition is unlikely to change without catastrophic disturbances occurring.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

No description available.

Mountain precipitation, as a major component of global ecology and culture, requires diverse observation-based distribution studies to improve process characterisation and so enhance environmental management and understanding. Analysis of data from an array of precipitation gauges within the nationally important, and internationally extreme, mountainous Lake Pukaki catchment in New Zealand has been undertaken in an effort to provide such a study, while also improving local hydrological understanding. An objective observation based undercatch-corrected 1971-2000 average annual precipitation distribution has been prepared for the mountainous Lake Pukaki catchment, New Zealand. Precipitation records from 58 gauges at 51 sites, augmented with 10 new gauges, were used in preparation of the distribution. The assessed undercatch correction of 17 % across the catchment indicates that mountain hydrological investigations in New Zealand that use precipitation data and yet do not consider undercatch will be in considerable error. The average annual distribution confirms the existence of high precipitation magnitudes and horizontal gradients in the catchment in comparison with other mountain regions around the world. The high magnitude is unusual when its position in the lee of the principal orographic divide is considered indicating rare precipitation distribution processes occur in the region. Consideration of river flows, glacial change and evaporation led to a confirmation of the gauge derived average catchment precipitation. Precipitation to wind direction relationships identified the predominant westerly wind to be the primary precipitation generating direction with large magnitude events biased towards the northerly direction. All directions from the eastern side of the mountain divide had the lowest frequency and daily precipitation magnitude. Derivation of wind-classed precipitation distributions identified a distinctive south east to north west precipitation gradient for all wind directions, most severe for the north west direction and least severe for the easterly direction. Precipitation extent was greatest for the northerly direction and least for the south south westerly. The wind-classed distributions enable the estimation of daily precipitation likelihood and magnitude at any location in the catchment based on knowledge of the synoptic wind flow direction and precipitation at just one reference site. Improved river flow and lake inflow estimates resulted from the use of wind classed daily precipitation estimates validating the quality of the wind classed distributions. From 1939 to 2000 there has been no statistically significant trend in precipitation magnitudes, frequencies, or extremes in the catchment. At Aoraki/Mt Cook village, in the upper catchment, there have been significant increases in magnitude, frequency and extremes associated with the phase change of the Interdecadal Pacific Oscillation (IPO) in 1978. This change can be explained by the increase in strength of westerly winds for the different IPO phases but not by a change in frequency of different wind directions. In the lower catchment the IPO relationship is of an opposite sense to that observed in the upper catchment, indicating that the areas operate under two different climate regimes with different precipitation controls. The significant relationship to the IPO phase indicates that it is more important than climate warming in terms of future precipitation distribution in the Lake Pukaki catchment, and by extension the Southern Alps. The distributions prepared provide a valuable tool for operational and academic hydrological applications in the region. In addition, they provide a valuable characterisation of the precipitation in a Southern Hemisphere mid-latitude lee to predominant westerlies glacierized mountain catchment. From this standpoint they highlight the contrast to Northern Hemisphere mountain precipitation distributions commonly used in model validation studies, thereby providing an extension of locations with which to refine orographic precipitation process understanding.

220 pp. / A collection of hands-on, interactive activities designed to engage youth in understanding purposes, uses, applications, and designs of rainwater harvesting systems. Together the activities promote a culture of conservation through the development of rainwater harvesting demonstration and use projects, encouragement of community awareness and action, and optimally the reduction of groundwater and surface water use.

This study gives a phenomenologically based stochastic model of space-time rainfall. Specifically, two random variables on the spatial rainfall, e.g., the cumulative rainfall within a season and the maximum cumulative rainfall per rainfall event within a season are considered. An approach is given to determine the cumulative distribution function (c.d.f.) of the cumulative rainfall per event, based on a particular random structure of space-time rainfall. Then the first two moments of the cumulative seasonal rainfall are derived based on a stochastic dependence between the cumulative rainfall per event and the number of rainfall events within a season. This stochastic dependence is important in the context of the spatial rainfall process. A theorem is then proved on the rate of convergence of the exact c.d.f. of the seasonal cumulative rainfall up to the iᵗʰ year, i ≥ 1, to its limiting c.d.f. Use of the limiting c.d.f. of the maximum cumulative rainfall per rainfall event up to the iᵗʰ year within a season is given in the context of determination of the 'design rainfall'. Such information is useful in the design of hydraulic structures. Special mathematical applications of the general theory are developed from a combination of empirical and phenomenological based assumptions. A numerical application of this approach is demonstrated on the Atterbury watershed in the Southwestern United States.

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