In order to assess the performance of water management approaches and irrigation systems used by the sugar industry in the Lowveld of Zimbabwe, a sugarcane yield and irrigation systems simulation model was developed. The model, named ZIMsched 2.0, was used to predict how field derived indices of irrigation systems performance, such as the coefficient of uniformity, CV, impacted on estimated recoverable crystal, ERC, yields and the water balance. This was done across a range of soil conditions, seasonal climates, irrigation system types and existing and refined irrigation scheduling strategies. Results of a verification study of the model showed an index of agreement, 'd', equal to 0.96 and a Pearson's correlation coefficient equal to 0.94, between observed and simulated yields of ERC, relative to a reference treatment. Application of the model showed the actual and also the potential performance of the different irrigation system hardware. Additional applications of the tools and information which were developed as a result of this research included an integrated economic assessment of peak irrigation system design specifications and associated deficit irrigation watering strategies. In an effort to translate theoretical water savings into practical realities a range of novel water management tools was also developed. Most of the drip irrigation systems in the Lowveld were performing below potential due to excessive infield variations in applied water. The performance of furrow irrigation systems was limited by the large variations in water applied to individual furrows, and water applications that were, on average, excessively high relative to soil water holding characteristics. Simulations showed that sub-surface drip irrigation systems have a slight edge on other irrigation systems in terms of potential efficiency. Average water savings for drip irrigation systems ranged from approximately 2.2 to 1.5 Ml/ha relative to floppy irrigation systems, and 3.5 to 2.3 Ml/ha relative to typical furrow irrigation systems, depending on how water applications were scheduled. A major finding was that there was potential for the Lowveld sugar industry to use up to 30% less water per hectare on an annual basis if ZIMsched, a specialist spreadsheet-based irrigation scheduling tool developed during the course of the project, was used to derive more appropriate and system specific water management guidelines. However, simulations showed that with the more precise irrigation scheduling there could be a slight crop yield penalty when the distribution uniformity of applied water was poor. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.

In order to assess the performance of water management approaches and irrigation systems used by the sugar industry in the Lowveld of Zimbabwe, a sugarcane yield and irrigation systems simulation model was developed. The model, named ZIMsched 2.0, was used to predict how field derived indices of irrigation systems performance, such as the coefficient of uniformity, CV, impacted on estimated recoverable crystal, ERC, yields and the water balance. This was done across a range of soil conditions, seasonal climates, irrigation system types and existing and refined irrigation scheduling strategies. Results of a verification study of the model showed an index of agreement, 'd', equal to 0.96 and a Pearson's correlation coefficient equal to 0.94, between observed and simulated yields of ERC, relative to a reference treatment. Application of the model showed the actual and also the potential performance of the different irrigation system hardware. Additional applications of the tools and information which were developed as a result of this research included an integrated economic assessment of peak irrigation system design specifications and associated deficit irrigation watering strategies. In an effort to translate theoretical water savings into practical realities a range of novel water management tools was also developed. Most of the drip irrigation systems in the Lowveld were performing below potential due to excessive infield variations in applied water. The performance of furrow irrigation systems was limited by the large variations in water applied to individual furrows, and water applications that were, on average, excessively high relative to soil water holding characteristics. Simulations showed that sub-surface drip irrigation systems have a slight edge on other irrigation systems in terms of potential efficiency. Average water savings for drip irrigation systems ranged from approximately 2.2 to 1.5 Ml/ha relative to floppy irrigation systems, and 3.5 to 2.3 Ml/ha relative to typical furrow irrigation systems, depending on how water applications were scheduled. A major finding was that there was potential for the Lowveld sugar industry to use up to 30% less water per hectare on an annual basis if ZIMsched, a specialist spreadsheet-based irrigation scheduling tool developed during the course of the project, was used to derive more appropriate and system specific water management guidelines. However, simulations showed that with the more precise irrigation scheduling there could be a slight crop yield penalty when the distribution uniformity of applied water was poor. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.

In order to assess the performance of water management approaches and irrigation systems used by the sugar industry in the Lowveld of Zimbabwe, a sugarcane yield and irrigation systems simulation model was developed. The model, named ZIMsched 2.0, was used to predict how field derived indices of irrigation systems performance, such as the coefficient of uniformity, CV, impacted on estimated recoverable crystal, ERC, yields and the water balance. This was done across a range of soil conditions, seasonal climates, irrigation system types and existing and refined irrigation scheduling strategies. Results of a verification study of the model showed an index of agreement, 'd', equal to 0.96 and a Pearson's correlation coefficient equal to 0.94, between observed and simulated yields of ERC, relative to a reference treatment. Application of the model showed the actual and also the potential performance of the different irrigation system hardware. Additional applications of the tools and information which were developed as a result of this research included an integrated economic assessment of peak irrigation system design specifications and associated deficit irrigation watering strategies. In an effort to translate theoretical water savings into practical realities a range of novel water management tools was also developed. Most of the drip irrigation systems in the Lowveld were performing below potential due to excessive infield variations in applied water. The performance of furrow irrigation systems was limited by the large variations in water applied to individual furrows, and water applications that were, on average, excessively high relative to soil water holding characteristics. Simulations showed that sub-surface drip irrigation systems have a slight edge on other irrigation systems in terms of potential efficiency. Average water savings for drip irrigation systems ranged from approximately 2.2 to 1.5 Ml/ha relative to floppy irrigation systems, and 3.5 to 2.3 Ml/ha relative to typical furrow irrigation systems, depending on how water applications were scheduled. A major finding was that there was potential for the Lowveld sugar industry to use up to 30% less water per hectare on an annual basis if ZIMsched, a specialist spreadsheet-based irrigation scheduling tool developed during the course of the project, was used to derive more appropriate and system specific water management guidelines. However, simulations showed that with the more precise irrigation scheduling there could be a slight crop yield penalty when the distribution uniformity of applied water was poor. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.

The near collapse of the Zimbabwean sugarcane industry in 1991/1992 was concluded to be as a result of critical water shortages. This, combined with the uncertainty in the availability of water and a climate characterised by recurring droughts, strongly motivated the sugarcane industry in the South-East Lowveld to strive for improvements in water management and led to the establishment of the Mobile Irrigation Performance Unit (MIPU) in April 2000. Following an extensive literature review, evaluation methods and performance parameters were determined for the different irrigation systems currently in use in the sugarcane industry within the Lowveld of Zimbabwe, in relation to international standards. The systems in use included furrow, centre pivot, hand-move sprinkler, static sprinkler and sub-surface drip. The study also resulted in the development of some novel evaluation tools, examples being a simple device to measure the inflow to irrigation furrows and a uniquely shaped nozzle, used to determine operating pressures within the sub-surface drip system. Factors that can affect a system's performance were investigated and a comparison of the different irrigation system's performance parameters was shown. The evaluation results obtained by the Lowveld MIPU were also compared to MIPU results obtained internationally and reported in the literature. The MIPU evaluations are considered to be of great benefit to the farmer because an extensive database of irrigation system performance has been collated, against which farmers can benchmark their systems in the future. It is also possible that the repetitive nature of certain management and design variables which may be detrimental to system performance under local conditions, can eventually be rendered obsolete, for example, incorrect assumptions in scheduling of irrigation. The evaluation data can also be used to help facilitate objective decisions regarding the selection of irrigation systems to suit particular environments. The research indicates that the sugarcane industry could derive major benefits in improved irrigation systems performance by ensuring that irrigation system operators have the required calibre of skills and sufficient training. The results reported here should benefit farmers and result in refinements to the crop production system rendering it more cost effective and efficient. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007.

Sugarcane is an important crop for South Africa. It provides employment and valuable foreign / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007

South Africa is a water scarce country. As pressure on available water resources increases, irrigation, the largest consumer of water, has to find ways of improving water use efficiency. Benchmarking in the irrigation sector has been identified as a suitable technique to implement this improvement. Benchmarking can be broadly defined as the identification and application of organisation specific best practices with the goal of improving competitiveness, performance and efficiency. A South African sugarcane irrigation scheme was identified to investigate a proposed benchmarking methodology. The scheme was unique in that electromagnetic flow meters were utilised and monitored on a daily basis. This facilitated an in depth study into irrigation water use at the scheme. The project focused on three different objectives. The first objective was to determine the losses, and consequently the efficiency, with which the irrigation scheme was able to deliver irrigation water from the water source to the farm boundary during the years 2004 and 2005. This was achieved by completing the water balance for the scheme with specified geographic and temporal boundaries. Results indicated that the scheme was very efficient with a delivery efficiency of 83.4 and 94.0 % for 2004 and 2005 respectively. These efficiencies were above the accepted South African Department of Water Affairs and Forestry (DWAF) standard of 80 %. The temporal distribution of the delivery efficiency was also investigated to identify periods within each year when inefficiencies occurred, and to better understand the nature of potential losses. It was concluded that the investigations into the temporal distributions be utilised together with the water balance approach in future studies into the performance of irrigation water delivery infrastructure at other South African irrigation schemes. The second objective was to calculate a set of internationally applied external irrigation benchmarking indicators. External indicators from the International Water Management Institute (1WMI), the International Program for Training and Research in Irrigation and Drainage (IPTRID) and the Irrigation Training and Research Center (ITRC) were reviewed for application in a South African context. The external indicator analysis highlighted that at a scheme level, insufficient irrigation was occurring to effectively meet the irrigation demand. It was also found that the scheme infrastructure was not the limiting cause of this observation. The external indicator results highlighted the need for additional schemes for comparison purposes. The results from this component of the study also emphasized the importance of stakeholder confidentiality concerns when attempting to implement a benchmarking initiative. The third objective was to rank individual farm performance of all the farms in the scheme, in terms of total farm sugarcane yield and seasonal irrigation water use. Farm yield and irrigated area were obtained to investigate the relationships between yield and irrigation water application. There were substantial variations in total farm yield and water use for both the 2004 and 2005 seasons, indicating much potential for improvement by many farmers relative to each other. The individual seasonal farm water use was also compared to a simulated irrigation demand, as determined with the SAsched irrigation systems and crop yield model. Simulation results with the SAsched model, using representative soils and climate data for the scheme, showed that the majority of farms were under irrigating relative to the simulated demands, especially in the late spring/early summer period. From on-farm irrigation system evaluations that were performed, it was found that irrigation system capacity constraints were not limiting irrigation applications in the majority of farms. Further research in the form of selected soil water monitoring is required to investigate these observations further. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2007.

River stage or flow rates are required for the design and evaluation of hydraulic structures. Most river reaches are ungauged and a methodology is needed to estimate the stages, or rates of flow, at specific locations in streams where no measurements are available. Flood routing techniques are utilised to estimate the stages, or rates of flow, in order to predict flood wave propagation along river reaches. Models can be developed for gauged catchments and their parameters related to physical characteristics such as slope, reach width, reach length so that the approach can be applied to ungauged catchments in the region. The objective of this study is to assess Muskingum-based methods for flow routing ill ungauged river reaches, both with and without lateral inflows. Using observed data, the model parameters were calibrated to assess performance of the Muskingum flood routing procedures and the Muskingum-Cunge method was then assessed using catchment derived parameters for use in ungauged river reaches. The Muskingum parameters were derived from empirically estimated variables and variables estimated from assumed river cross-sections within the selected river reaches used. Three sub-catchments in the Thukela catchment in KwaZulu-Natal, South Africa were selected for analyses, with river lengths of 4, 21 and 54 km. The slopes of the river reaches and reach lengths were derived from a digital elevation model. Manning roughness coefficients were estimated from field observations. Flow variables such as velocity, hydraulic radius, wetted perimeters, flow depth and top flow width were determined from empirical equations and cross-sections of the selected rivers. Lateral inflows to long river reaches were estimated from the Saint-Venant equation. Observed events were extracted for each sub-catchment to assess the Muskingum-Cunge parameter estimation method and Three-parameter Muskingum method. The extracted events were further analysed using empirically estimated flow variables. The performances of the methods were evaluated by comparing both graphically and statistically the simulated and observed hydrographs. Sensitivity analyses were undertaken using three selected events and a 50% variation in selected input variables was used to identify sensitive variablesThe performance of the calibrated Muskingum-Cunge flood routing method using observed hydrographs displayed acceptable results. Therefore, the Muskingum-Cunge flood routing method was applied in ungauged catchments, with variables estimated empirically. The results obtained shows that the computed outflow hydrographs generated using the Muskingum-Cunge method, with the empirically estimated variables and variables estimated from cross-sections of the selected rivers resulted in reasonably accurate computed outflow hydrographs with respect to peak discharge, timing of peak flow and volume. From this study, it is concluded that the Muskingum-Cunge method can be applied to route floods in ungauged catchments in the Thukela catchment and it is postulated that the method can be used to route floods in other ungauged rivers in South Africa. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.

Automated short furrow irrigation (ASFI) is a prototype irrigation system that has the potential to be robust and relatively low-cost, with highly effective and efficient water use. ASFI has low energy requirements because the pressure at the field edge is relatively low, typically 70 kPa (or 7 m) as compared with approximately 150 kPa for drip and 400 kPa for dragline systems. However, at project onset, the only type of ASFI system tested was Microfurrow which was, among other problems, not robust. The aim of this project was, therefore, to develop, implement and evaluate a suitable ASFI system and to compare the system to a reference sub-surface drip (SSD) irrigation system with sugarcane as the test crop. This process resulted in the development of a boot and piston valve, which was used to automatically control the flow between specific plots. The valve was then implemented, as per design, in the ASFI system at a trial at the University of KwaZulu-Natal’s Ukulinga research farm. Irrigation events were scheduled according to SAsched with the aim of applying equivalent amounts of water to both the ASF and SSD treatments. The testing and evaluation included irrigation uniformity tests and the crop yields. Evaluation of selected furrows in the ASFI treatment showed a low quarter distribution uniformity (DUlq) range between 72 % and 80 %. This is considerably better than approximately 60 % for conventional furrow irrigation. However, the DU for ASFI could be improved to above 90 % if the slope was reduced from 1:40 to approximately 1:250. Both the harvested tons per hectare and sucrose content results were evaluated using a one-way statistical analysis with differences between the results deemed to be insignificant. Therefore, the ASFI performance in terms of harvest data for the Ukulinga trial could be described as “similar to” SSD irrigation. A 10 ha sample ASFI system was designed and compared in economic terms with a respective SSD system. Although further piping options can be explored in order to reduce the capital costs of the ASFI system even further, ASFI was considerably more cost-effective than the SSD system in terms of operating and fixed costs per hectare. The ASFI irrigation system, although having some initial maintenance requirements in insuring all furrows performed properly, required no other maintenance throughout the year in the Ukulinga trial. The drip system, however, required laterals to be flushed and leaks to be repaired. It is therefore believed that the ASFI system meets the required objectives of the project in that it is robust, low-cost (both operating and fixed) and able to supply water efficiently and effectively. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The goal of irrigation is to supply sufficient water for crop growth to all areas within a field. Therefore, the uniformity of application of irrigation water is of great importance. The objectives of this study were to quantify the performance of irrigation systems under field conditions using standard evaluation techniques and to investigate the use of spatial statistics to characterise the spatial variability of application. The main objective was to develop techniques to estimate gross irrigation water requirement that incorporates the uniformity of application. Different practitioners have given different definitions to the criteria used to evaluate the performance of an irrigation system. A literature review was conducted to determine the current definitions used and the factors that affect these performance criteria. The theory and application of spatial statistics was investigated in order to charaterise spatial distribution of irrigation water. The spatial distribution of irrigation water under centre pivots was determined using field measurements. A number of centre pivot, sprinkler, floppy, drip and micro-irrigation systems were evaluated using standard techniques. The results from the evaluation of spatial data show that this approach is useful to determine a map of the distribution of applied irrigation water. Due to the smoothing characteristic of the spatial statistical method employed, the maps have a uniformity that is greater than in reality. The results from the standard evaluation techniques show that quick and representative results for the performance of an irrigation system can be obtained. The distribution uniformity has an affect on the efficiency of a system and should therefore be included in the calculation of the gross irrigation water requirement. The methods for these calculations are discussed. Further research needs to be conducted to determine actual distribution uniformities and application efficiencies for irrigation systems under various field conditions. This will provide useful standards to include in the calculation of gross irrigation water requirements. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Steam distillation is the most widely accepted process for the large scale production of volatile essential oils from herbaceous material and is also regarded as the standard practice throughout the flavour and fragrance industry. A mobile essential oil distillation unit for the extraction of oils from herbaceous materials would be extremely valuable to the essential oil industry in South Africa. Using a mobile platform, the extraction technology could be taken to rural areas where essential oil crops are grown in order to extract and then analyse the oils produced. Existing systems in South Africa are static distillation units which are usually owned by commercial growers that are generally positioned large distances away from the rural areas. The objective of this project was to design, construct and test a prototype mobile distillation unit for the extraction of essential oils from herbaceous materials. The unit was to have a charge vessel capacity of approximately 250 kg of plant material and should be able to perform in-field distillations in areas where electricity is not available. A literature review on all the essential oil extraction methods, the theory behind steam distillation and oil isolation and the effect that each of the distillation components have on the distillation process was performed. A small test distillation unit was set up in a laboratory in order to investigate the effects of varying steam flow . rates on the distillation time, oil yield and oil quality. A double charge vessel unit was designed, constructed and mounted onto a frame which in turn was fixed onto a trailer to be hauled by a light delivery vehicle (LDV). The steam generator with all its ancillary equipment was fixed onto a separate trailer. The unit could thus be easily transported and in-field distillations on various crops could be conducted. Field distillations were conducted with two crop types, namely rose geranium and lemon grass. Satisfactory results were obtained as the oil yields were within the expected oil yield range. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.