Desalination of seawater is a widely used technology throughout the world, but is not commonly used in South Africa for domestic water supply. The reasons for this are varied, but very often are based on the assumption that desalination is extremely costly in relation to more traditional water supplies. An economic analysis is undertaken comparing the cost of supplying water to the coastal town of Zinkwazi from various sources including desalination using reverse osmosis. Zinkwazi has an existing borehole water supply that is insufficient to meet current and future demands. The town is also remote from regional bulk surface water infrastructure, which makes it suitable for the investigation of an alternative stand-alone water supply such as desalination. Solving the water supply problems at Zinkwazi is important to Umgeni Water and would support two broad strategic goals of the organisation. Zinkwazi falls within the Ilembe District Municipality, which is an important stakeholder within Umgeni Water's area of jurisdiction. Improving the water supply situation at Zinkwazi is in line with Umgeni Water's goal of assisting Municipalities to meet their developmental objectives. Using desalination to meet this objective is in line with Umgeni Water's goal of using innovative products to alleviate problems of existing customers. Desalination is a multi-billion dollar industry that is growing as traditional surface and goundwater resources become fully utilized and more polluted. Desalination potentially represents a growth opportunity that Umgeni Water, with its expertise in water treatment and supply, could pursue in Africa and Southern Africa in particular. The investigation found that desalination is the most affordable method of supplying water to the town of Zinkwazi and the construction of a desalination pilot plant is recommended for further investigation. / Thesis (MBA)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Water is characterised by both its quantity (availability) and its quality. Salinity, which is one of the major water quality parameters limiting use of a wide range of land and water resources, refers to the total dissolved solutes in water. It is influenced by a combination of several soil-water-salt-plant related processes. In order to develop optimum management schemes for environmental control through relevant hydrological modelling techniques, it is important to identify and understand these processes affecting salinity. Therefore, the various sources and processes controlling salt release and transport from the soil surface through the root zone to groundwater and streams as well as reservoirs are extensively reviewed in this project with subsequent exploration of some hydro salinity modelling approaches. The simulation of large and complex hydrological systems, such as these at a catchment scale, requires a flexible and efficient modelling tool to assist in the assessment of the impact of land and water use alternatives on the salt balance. The currently available catchment models offer varying degrees of suitability with respect to modelling hydrological problems, dependent on the model structure and the type of the approach used. The A CR U agrohydrological modelling system, with its physically-conceptually based characteristics as well as being a multi-purpose model that is able to operate both as a lumped and distributed model, was found to be suitable for hydro salinity modelling at a catchment scale through the incorporation of an appropriate hydro salinity module. The main aim of this project was to develop, validate and verify a hydro salinity module for the ACRU model. This module is developed in the object-oriented version of ACRU, viz. ACRU2000, and it inherits the basic structure and objects of the model. The module involves the interaction of the hydrological processes represented in ACRU and salinity related processes. Hence, it is designated as ACRUSalinity. In general, the module is developed through extensive review of ACRU and hydrosalinity models, followed by conceptualisation and design of objects in the module. It is then written in Java object-oriented programming language. The development of ACRUSalinity is based mainly on the interaction between three objects, viz. Components, Data and Processes. Component objects in ACRU2000 represent the physical features in the hydrological system being modelled. Data objects are mainly used to store data or information. The Process objects describe processes that can take place in a conceptual or real world hydrological system. The Process objects in ACRUSalinity are grouped into six packages that conduct: • the initial salt load determination in subsurface components and a reservoir • determination of wet atmospheric deposition and salt input from irrigation water • subsurface salt balance, salt generation and salt movement • surface flow salt balance and salt movement • reservoir salt budgeting and salt routing and • channel-reach salt balancing and, in the case of distributed hydro salinity modelling, salt transfer between sub-catchments. The second aim of the project was the validation and verification of the module. Code validation was undertaken through mass balance computations while verification of the module was through comparison of simulated streamflow salinity against observed values as recorded at gauging weir UIH005 which drains the Upper Mkomazi Catchment in KwaZuluNatal, South Africa. Results from a graphical and statistical analysis of observed and simulated values have shown that the simulated streamflow salinity values mimic the observed values remarkably well. As part of the module development and validation, sensitivity analysis of the major input parameters of ACRUSalinity was also conducted. This is then followed by a case study that demonstrates some potential applications of the module. In general, results from the module evaluation have indicated that ACRUSalinity can be used to provide a reasonable first order approximation in various hydrosalinity studies. Most of the major sources and controlling factors of salinity are accommodated in the ACRUSalinity module which was developed in this project. However, for a more accurate and a better performance of the module in diversified catchments, further research needs to be conducted to account for the impact of salt loading from certain sources and to derive the value of some input parameters to the new module. The research needs include incorporation in the module of the impact of salt loading from fertilizer applications as well as from urban and industrial effluents. Similarly, further research needs to be undertaken to facilitate the module's conducting salt routing at sub-daily time step and to account for the impact of bypass flows in heavy soils on the surface and subsurface salt balances. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

An unresolved problem in hydrology has been to establish relationships between catchment attributes and the flow characteristics of the stream. Such information is commonly sought to improve streamflow predictions, often in a process of extrapolating research results obtained from relatively few, but intensively studied catchments, to a broader region. This study has attempted to clarify terminology related to streamflow generation processes and mechanisms, and to investigate relevant physiographic and climatic characteristics which critically influence the hydrological responses of catchments. Fourteen catchments were selected for this study. They comprised both operational and research catchments. These catchments were selected to be representative of variations in climate, topography, vegetation and geology occurring throughout the Republic of South Africa (RSA). The selection of catchments was also restricted to areas less than 100 krrr', and to the higher rainfall regions of the country, where runoff is significant and any land use changes may lead to marked changes in evapotranspiration and streamflow. A catchment was also selected from an arid zone in the USA, to capture the flow characteristics that are typical of such areas. A frequently applied simulation model on RSA catchments is the ACRU model. While physical-conceptual in structure it contains some parameters which, while not determining total streamflow magnitudes, governs the time distribution of the streamflows generated. Two such parameters from the ACRU model selected were the coefficient of baseflow response (COFRU) and the quickflow response fraction of the catchment (QFRESPj. These parameters are not explicitly physically based, and therefore improved guidelines of initial parameter values are required. Relationships between catchment characteristics and these two parameters were sought to provide guidelines for effective parameterisation of these parameters in future studies. Trends between QFRESP and COFRU, and catchment physical and climatic attributes such as catchment area, average depth of the soil profile, maximum basin relief, MAP and profile plant available water were identified, and could prove useful to future users of the ACRU model and guide experimentation in estimating initial parameter values. However, only a single significant multiple regression model was obtained for the baseflow release fraction COFRU from a catchment using MAP, catchment area and profile plant available water. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

The Umzimvubu catchment on the eastern coastal escarpment of South Africa is sensitive to anthropogenic influences,with commercial and subsistence agriculture, irrigation, domestic and rural settlements and forestry compete for water use. An adequate supply of water to the region is seen as imperative in the light of the recent establishment of forest cultivation. In order to provide a sound assessment of the impacts of afforestation on the catchment, the subsurface hydrological processes of hillslopes on the Molteno sedimentary formations of the region must be clearly understood. Since the runoff hydrograph is, to a large degree, dependent on the subsurface processes, a number of models that simulate small catchment runoff have been developed. However, recent successful application of tracer techniques to hydrological modelling has shown that the subsurface processes are still not fully understood (Schultz, 1999), and whether or not the subsurface processes are modelled adequately is most often not verified, since there is a lack of relevant data. It is, therefore imperative that the subsurface component of these small catchment runoff models be improved. This can be achieved by first observing detailed subsurface water dynamics and assessing these against the catchment runoff response. In this dissertation, results from a detailed experiment that was initiated in a 1.5 km2 catchment in the northern East Cape Province are shown. Nests of automated tensiometers, groundwater level recorders and weather stations have been placed at critical points around the catchment, and these , together with soil hydraulic and physical characteristics are used to define and identify the dominant hillslope processes. Two crump weirs record runoff from these hillslopes. The results of this subsurface study highlight the dynamics of surface and subsurface water in the hillslope transects. It is evident that the subsurface processes are strongly influenced by the -bedrock topography as well as the soil characteristics, such as macropore flow and deep percolation. Using the monitored data and 2-D vadose zone modelling, the dominant hillslope processes have been defined and are used to aid in the selection of critical parameters to be used in estimating the catchment runoff. Results show that a clear understanding of the subsurface dynamics can lead to a realistic estimation of catchment scale runoff response. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

There is a need in the South African sugar industry to investigate improved techniques for forecasting seasonal sugarcane yields. An accurate and timely forecast of seasonal cane yield is of great value to the industry, and could potentially allow for substantial economic savings to be made. Advances by climatologists have resulted in increasingly accurate and timely seasonal climate forecasts. These advances, coupled with the ongoing advances made in the field of crop yield simulation modelling, present the sugar industry with the possibility of obtaining improved cane yield forecasts. In particular, the lead time of these forecasts would be improved relative to traditional techniques. Other factors, such as the flexibility offered by simulation modelling in the representation of a variety of seasonal scenarios, would also contribute to the possibility of obtaining improved cane yield forecasts. The potential of applying crop yield simulation models and seasonal rainfall forecasts in cane yield forecasting was assessed in this research project. The project was conducted in the form of a case study in the Eston Mill Supply Area. Two daily time step cane yield simulation models, namely the ACRU-Thompson and CANEGRO-DSSAT models, were initially evaluated to test their ability to accurately simulate historical yields given an observed rainfall record. The model found to be the more appropriate for yield forecasting at Eston, the ACRU-Thompson model, was then used to generate yield forecasts for a number of seasons, through the application of seasonal rainfall forecasts in the model. These rainfall forecasts had previously been translated into daily rainfall values for input into the model. The sugarcane yield forecasts were then evaluated against observed yields, as well as against forecasts generated by more traditional methods, these methods being represented by a simple rainfall model and Mill Group Board estimates. Although the seasonal rainfall forecasts used in yield forecasting were found not to be particularly accurate, the proposed method provided more reliable cane yield forecasts, on average, than those using the traditional forecasting methods. A simple cost-benefit analysis indicated that the proposed method could potentially give rise to the greatest net economic benefits compared to the other methods. Recommendations are made for the practical implementation of such a method. Future areas of research are also identified. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

A final cover on a waste impoundment is the main physical barrier between the waste impoundment and the environment designed to protect against physical, chemical and biological factors isolating the waste from the atmospheric environment. Since the early 1990‟s regulators in the United States have started accepting vegetation covers in lieu of the prescriptive covers. Currently in South Africa, data that provide field performance comparisons of alternative vegetation covers are few or non-existent; hence a research program was undertaken by an industrial corporation in South Africa to determine the potential use of vegetation covers. In proposing a practical way forward, the Company (AECI Limited) reached an understanding with the Regulators that a vegetated evapotranspiration (ET) cover, would be acceptable provided that its performance in limiting surface water infiltration (and subsequent leaching) could be quantitatively demonstrated. The overall object of this research was to determine the capability of vegetation cover to limit effluent leaching from a waste impoundment. Analysis of the following sub-objectives were required to address and give answers to this study (1) determine, as accurately as possible a climatic water balance on the vegetation covers, (2) determine the geohydrological properties of the material of the waste impoundment, (3) determine the fate of the water i.e. proportion reused via evapotranspiration as opposed to the proportion infiltrating the waste body beneath the root zone and (4) determine the leaching potential below the waste. The study identifies and evaluates the climatic (above ground) and geohydrological (sub-surface) parameters used to estimate the water balance of the materials for a waste impoundment. The study then utilizes these parameters at the respective sites in a finite-element model, called the HYDRUS-2D model, to simulate the water balance of the material. The simulated water balance results were then compared against collected field data, which provide the evidence of the efficiency of a vegetation cover to limit effluent from the impoundment. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

South African water management areas could find themselves without enough water for its users due to new methods of performing water allocation as stipulated in the National Water Act of 1998. A water accounting system would address the need for accurate metering, monitoring and auditing of South Africa’s water resources to ensure that users are complying with their allocations. Such a system should be able to provide information such as comparisons between the simulated and observed flow of water at a point, comparisons between the amount of water allocated to a user and the actual water used by that user, and the source and destination of water at a point. This document contains a literature review, an explanation of the methods used to develop a prototype water accounting system and a discussion of the results from testing the system. A literature review was undertaken which covered topics in water resources planning, water resources operations, local legislation for water allocation and new technologies which could be applied to aid the management of water resources in South Africa. The results from the literature review indicated real time water accounting systems can give effect to water allocation rules. The water accounting system is comprised of two simulation models and a database. The models used for the study were the ACRU2000 model and the MIKE BASIN model. These models require data as well as a means to automate the transfer of data between the models and thus a database was developed. The database was developed in Microsoft Access and, in addition to the construction of a number of tables required to house the data, a database dashboard was made to control the functions of the database. An assessment of the ACRU2000 and MIKE BASIN models was performed in order to determine if they are suitable for use as water accounting tools. ACRU2000 was used for its process based, daily rainfall-runoff modelling capabilities. Due to the process based modelling capabilities of ACRU2000, forecasts of rainfall can be used as input to the simulations. Hot starting is the storing of internal model state variables at a particular time and the use of these variables in a different simulation to start the model up again. It was expected that, due to long simulation run times for ACRU2000, it would be beneficial to enable ACRU2000 to be hot started and an attempt to hot start ACRU2000 is presented. This would have allowed for significantly decreased simulation run times as the model can be warmed up for two years and thereafter hot started to run only for one day at a time. An assessment of the MIKE BASIN network allocation model to be used as a water accounting system was performed by attempting to meet the project objectives through building a fictional water supply network. The network is composed of a small catchment containing six runoff generating regions, a reservoir and ten water users. Three network allocation scenarios were constructed in order to fully test the rule sets and allocation capabilities currently available in the MIKE BASIN model. The study has shown that the tools and models used are capable of forming a rudimentary water accounting system. This is encouraging as it shows that there is the potential to improve the water resources management in South Africa using tools that already exist. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Hillslope mechanisms and processes are a complex and dynamic set of interactions, but are nevertheless vital components of hydrology due to their critical interactions with surface and groundwater (Lorentz, 2001a). In order to observe and quantify these flow generating mechanisms, the Weatherley subcatchment was selected where the components of streamflow generation have been studied and can be quantified separately. Surface, shallow subsurface and the deeper groundwater interactions are particularly important when quantifying runoff generation from within hillslope, riparian and wetland zones as they are the dominant runoff generating zones within the Weatherley catchment. These components of flow are important to quantify for the further study of flow generation mechanisms, their dynamics and fluxes at the hillslope and small catchment scale, low flow contributions, climate change as well as the consequences of land use change (Lorentz, 2001b). Transfer functions were found to be the best adaptation of hydrograph separation for distributed hydrological modelling purposes when attempting to quantify the various streamflow hydrograph components. In this study, the runoff components were simulated along transects using the HYDRUS-2D model, where the simulated soil water dynamics are compared with the observed tensions and water contents at different depths within the soil profile in order to quantify the contributing hillslope fluxes to streamflow generation. The 2001 data set was used with the rainfall and potential evapotranspiration data being converted into rates according to the breakpoint rainfall data. The HYDRUS-2D modelling exercise is performed to calculate the variety of flux rates (timing and quantities) within the subcatchment, so that the overall stream hydrograph can be properly deduced when modelling this catchment with transfer functions in the future. An understanding of the driving forces as well as the behaviour of sources and flow paths was extracted from this thesis, along with gaining some knowledge about the mechanisms and behaviour of streamflow generating mechanisms at the hillslope and small catchment scale. Troch et al (2003) clearly encapsulates the essence of modern day catchment hydrology in stating that hillslope response to rainfall remains one of the most central problems of catchment hydrology in order to quantify catchment responses. The processes whereby rainfall becomes runoff continue to be difficult to quantify and conceptualise (Uhlenbrook et al., 2003) and this is because the characterisation of subsurface water flow components is one of the most complex and challenging tasks in the study of the hydrologic cycle (Achet et al., 2002). Since trying to understand the temporal and spatial variability of moisture content and the subsurface flow mechanisms is a complicated problem (Achet et al., 2002), an attempt is made in this thesis to gain insights into the temporal and spatial variability of soil tensions and soil moisture content at various depths on hillslope transects by combining modelling exercises with field observations. From this modelling, the hillslope water balance and contributing fluxes are derived in effort to augment, at a later stage, the hillslope response functions. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

The South African sugar industry ranks eleventh in size out of 200 sugar-producing countries; and continuous advancement is essential to ensure that this industry remains competitive. The transfer system from field to mill, includes sugarcane being moved, loaded, transloaded and off-loaded and amounts to more than 25 % of the total production cost of sugarcane, hence small adjustments can have significant economic benefits. Payload variability is a current problem making the loading operation a leverage point for improvement. As a consequence of poor management and the under-utilisation of equipment, loading has been identified as an inefficient and costly operation. Studies have shown that technology and management can contribute to improved loading accuracy. This study aimed to evaluate loading characteristics in an attempt to develop guidelines for loading. Whole-stick loose sugarcane, which is loaded with grabloaders, is common practice in South Africa and this study aims to improve this loading system. This was achieved by reviewing transfer systems worldwide and synthesising the sugarcane characteristics that drive the designs and the management of equipment and systems within the transfer system. The sugarcane characteristics include the sugarcane bulk density, the length, the diameter and other variety characteristics e.g. the degree of lodging. Other factors, such as the preparation method for loading, the harvesting method and the topography, also have a marked influence on the efficiency of the transfer system. An assessment of typical South African loading practices was undertaken to establish beneficial practices and current operating rules. These factors included the way in which the sugarcane was presented prior to loading, as well as the techniques adopted for loading. The results were used to generate practical recommendations for the improvement of the loading component in order to make the transfer system more efficient. An efficient system comprises a balance of high quality operations with respect to safety, accurate loading, reduced cycle time, optimal fuel usage, reduced roadside losses, reduced sugarcane damage and increased off-loading efficiencies. An investigation into consignment characteristics was also carried out to identify the factors that need to be considered during the loading operation. These factors included the sugarcane bulk density, the degree of sugarcane alignment and the design characteristics of various vehicles. A set of practical guidelines were created from this study. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2011.

Demands on the water resources of South Africa are ever increasing owing to population growth and increased development of urban, peri-urban and rural communities. Problems in terms of water quantity and quality are likely to be experienced during baseflow recessions. It is therefore imperative that water resources managers not only understand these baseflow periods of streamflow, but are able to model them with confidence. Research for this study thus included a comprehensive literature survey of the factors which affect baseflow as well as the approaches that previous studies have utilised to analyse and model baseflow recession. The primary aims of this study were to establish a streamflow database, to construct master recession curves (MRCs) for each catchment under consideration, evaluate the assumption that South African rivers recede exponentially, to determine a representative set of catchment characteristics for use in the baseflow recession analysis, to attempt to explain the MRC trends using these catchment characteristics and to investigate the feasibility of establishing a rule based model for baseflow recession. A streamflow database for South Africa was therefore established. This consisted initially of 202 catchments which were deemed to be recording natural streamflow. MRCs were established for 134 of these catchments. Those MRCs which were established indicate that the majority of South African rivers do not conform to an exponential model of recession. In order to account for the trends defined by the MRCs, catchment area, average catchment slope, drainage density, mean annual precipitation, rainfall concentration, rainfall seasonality, two independent estimates of groundwater recharge and a geological index were calculated for each catchment. Limited success was achieved when the data set was divided into subsets in order to group catchments with similar baseflow recession responses. The geological composition of the catchments appeared to provide the best results in that those trends exhibited by the MRCs could be explained by the types and proportions of the lithologies present. Owing to the lack of readily useable results it was concluded that until further results were forthcoming the development of a rule based model for baseflow recession analysis in South Africa would be premature. The establishment of a readily accessible database containing streamflows and associated catchment characteristics lends itself to future research. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.