This thesis presents the results of exploratory sociological research designed to better understand how farmers select agricultural practices with the potential to effect water quality. The primary research methodology is a Rapid Rural Appraisal of thirty farms in five rural municipalities in Saskatchewan, Canada during the year 2000 growing season. The data establishes that a variety of economic, institutional, organizational, and social factors interact in dynamic ways to influence farmer resource management decisions and that the resulting agricultural practices have the potential for subtle and dramatic effects on water quality in Saskatchewan. Risk-mitigating farming methods known as Best Management Practices (BMPs) are interpreted by farmers in the field research as being both appropriate and problematic. Alternative initiatives and communication strategies are identified in the field data that offer support to production and productivity in the agriculture sector while also promoting water quality. The research suggests that measures such as providing accessible public water quality data, promoting water treatment for individual households, and educating rural women and youth about water quality issues may merit further investigation.

This thesis presents the results of exploratory sociological research designed to better understand how farmers select agricultural practices with the potential to effect water quality. The primary research methodology is a Rapid Rural Appraisal of thirty farms in five rural municipalities in Saskatchewan, Canada during the year 2000 growing season. The data establishes that a variety of economic, institutional, organizational, and social factors interact in dynamic ways to influence farmer resource management decisions and that the resulting agricultural practices have the potential for subtle and dramatic effects on water quality in Saskatchewan. Risk-mitigating farming methods known as Best Management Practices (BMPs) are interpreted by farmers in the field research as being both appropriate and problematic. Alternative initiatives and communication strategies are identified in the field data that offer support to production and productivity in the agriculture sector while also promoting water quality. The research suggests that measures such as providing accessible public water quality data, promoting water treatment for individual households, and educating rural women and youth about water quality issues may merit further investigation.

El desenvolupament de mètodes d'anàlisi de compostos fenòlics és una pràctica habitual en molts laboratoris des de l'establiment de mesures legislatives de control de les concentracions d'aquestes substàncies en el medi ambient. Les tècniques cromatogràfiques representen la primera opció per a la determinació de la major part de compostos orgànics, en els que s'inclouen els fenols. Aquests, per les seves propietats de volatilitat i polaritat, poden analitzar-se emprant tant la cromatografia líquida com la cromatografia de gasos i aquesta dualitat s'ha aplicat en aquest treball. / Phenols form a heterogenic compound family that has been found to have a detrimental effect on human health and to alter the taste and odour of water. Given the production of these contaminating compounds has increased considerably, both the EU and the EPA have established limits for the presence in the environment. The strictness of this legislation has made it necessary to develop more sensitive analytical methods to allow the detection of phenols at trace levels and to monitor their distribution in the different environmental contexts in which they are found.

A new technique for sample preparation and trace analysis of organic pollutants in water using mixed-phase thin film (MPTF) devices, combined with direct thermal desorption, cold trapping, gas chromatography-mass spectrometry (GC-MS) is presented for the first time. Two novel analytical devices, Carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) TF samplers were fabricated using spin coating technique and glass wool fabric mesh as substrate. The samplers were easily tailored in size and shape by cutting tools. Good durability and flat-shape stability were observed during extractions and stirring in water. The latter characteristic obviates the need for an extra framed holder for rapid thin film microextraction (TFME) and makes the samplers more robust and user-friendly. The analytical performance of the MPTF devices was satisfactorily illustrated and compared with those of solid phase microextraction (SPME) fibers and PDMS thin film membrane using water samples spiked with seven N–nitrosamines (NAs), known as disinfection by-products (DBPs) in drinking water. Marked enhancement of extraction efficiencies (typically more than one order of magnitude) for the N-nitrosamines, including the hydrophilic ones, was obtained with the MPTF devices under generally pre-equilibrium conditions, compared to the SPME fibers and PDMS thin film membrane. The analytical results obtained in this study, including linearity, repeatability and detection levels at low ng/L for the tested compounds, indicate that the new thin film devices are promising for rapid sampling and sample preparation of trace levels of polar organic pollutants in water with sensitivities higher than SPME fibers and with a wide application range typical of mixed-phase coatings. The user-friendly format and robustness of the novel devices are also advantageous for on-site applications, which is the ultimate use of thin film samplers. Moreover, the thin film fabrication approach developed in this study offers the possibility of making other novel samplers with PDMS or different absorptive polymers such as polyacrylate (PA) and polyethylene glycol (PEG) as particle-free, or as particle-loaded thin films with a variety of adsorptive solid particles. In another development in the course of this research, the performance and accuracy of the SPME fiber approach for sample preparation of selected DBPs were demonstrated and compared with the conventional liquid-liquid extraction (LLE) method by real drinking water samples analysis in collaboration with Health Canada. Four regulated trihalomethanes (THMs) and seven other DBPs known as priority by-products, including four haloacetonitriles, two haloketones and chloropicrin, were analyzed in real samples during two separate comparative studies. In each study, duplicate samples from several water treatment and distribution systems in Canada, collected and stabilized under the same protocol, were analyzed in parallel by two independent labs; in the University of Waterloo by an optimized headspace SPME-GC-MS and in Health Canada by a LLE-GC-ECD (electron capture detection) method equivalent to EPA 551.1. The values for the concentration of the analytes in the samples obtained by the two methods were in good agreement with each other in majority of the cases indicating that SPME affords the promise of a dependable sample preparation technique for rapid DBPs analysis. In particular, it was shown that the SPME fiber approach combined with GC-MS is a fast reliable alternative to the LLE-GC-ECD (EPA 551.1) method for analysis of the regulated THMs in the concentration ranges that are typical and relevant for drinking water samples.

This thesis examines geomorphic processes that impact thermal stratification within floodplain lakes. Previously, thermal stratification was not thought prevalent in these numerous small water bodies, despite being found in small reservoirs. Thermal stratification leads to long term anoxia in the bottom waters and the release of metals and nutrients from the sediments. This can result in water quality problems such as algal blooms (including potentially toxic cyanobacteria), loss of fish habitat and deterioration of wetland habitat. Four floodplain lakes of the Macdonald River Valley NSW were profiled and tested over 3?? years to assess to what extent, under what conditions, and with what chemical and physical effects, they thermally stratified and destratified. The morphometry, bed facies, vegetation, hydrology and local weather patterns for each lake were also investigated. Physical and chemical analyses found elevated nutrients in all four lakes and higher concentrations of total phosphorous and total nitrogen in the bottom waters. These results were not dependant on stable thermal stratification and long-term anoxia in the bottom waters. Inflow samples had much higher concentrations of nutrients than the lake samples, so the catchment is the likely source. Samples were analysed for phytoplankton and significant populations of potentially toxic cyanobacteria were present. Stratification depended upon whether the lake was "sheltered" from wind stirring or from incident radiation, either topographically by steep slopes surrounding the lakes, or by submerged and emergent vegetation. Aquatic vegetation limits the amount of transfer of turbulent kinetic energy from wind shear and the amount of incident radiation received. At one lake, sheltered areas reached temperatures much higher than less sheltered areas. Topographic sheltering can make a difference of up to three degrees Celsius across the lake surface. Destratification depended on wind speed, wind direction and orientation of the lake to the dominant wind direction. An extension to the classification of fluvial lakes (from Timms 1992) is presented, with further subdivisions to describe the lakes as "sheltered" or "open" and the type of sheltering (vegetation or topography) present.

This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.

A qualidade da água e preservação dos ambientes aquáticos assumiu papel fundamental para a sustentabilidade, não só relacionado ao abastecimento, mas também à preservação destes ecossistemas. O uso da água, especialmente para abastecimento dos centros urbanos e irrigação na agricultura tem favorecido a tendência à diminuição das reservas de águas limpas e consequentemente a menor diluição de poluentes presentes, entre eles os pesticidas. Os pesticidas fazem parte do grupo de poluentes que podem gerar impactos significativos nos ambientes em que são inseridos, impactos dos quais alguns ainda não são totalmente conhecidos. Em função do crescente aumento da demanda por alimentos e sua consequente necessidade de se obter maior produtividade, o uso de pesticidas tem aumentado significativamente favorecendo o aumento destes impactos. Este modelo agrícola de produção é predominante em todo o mundo e resulta na presença destes poluentes nos mais diversos ambientes aquáticos, especialmente os superficiais próximos a regiões de cultivo. Neste contexto, o monitoramento destes poluentes em campo indica seu destino nos ambientes próximos à sua aplicação demonstrando mais fielmente seu comportamento neles, bem como fornece informações de referência para programas de monitoramento e avaliação de pesticidas nestes ambientes. O presente estudo avaliou amostras de água e sedimento do Rio Piquiri, localizado em uma região de alta produção de trigo, soja e milho, no estado do Paraná, Brasil. Este rio sofre influência direta da aplicação de pesticidas das lavouras da região. As amostras de água foram extraídas com uma mistura de diclorometano:hexano e as amostras de sedimento com uma mistura de acetona:hexano, tendo sido concentradas 500 vezes para as amostras de água e 25 vezes para as de sedimento. Os extratos foram analisados em LC/MS/MS e confirmaram a presença dos herbicidas e fungicidas utilizados na região do estudo conforme dados oficiais de comercialização no período das coletas. Os resultados mais expressivos nas amostras de água foram do herbicida Atrazina, 0,030 μg L-1 e do fungicida Carbendazim, 0,178 μg L-1. No sedimento os maiores valores encontrados foram para os fungicidas Carbendazim 26,8 μg L-1 e Azoxistrobina, 0,712 μg L-1, ambos na terceira coleta no ponto de coleta 3. / Water quality and conservation of aquatic environments assumed a leading condition for sustainability, not only related to the supply, but also the preservation of these ecosystems. The use of water, especially for supply to urban centers and irrigation in agriculture has favored upon the decrease of the reserves of clean water and therefore less dilution of pollutants, including pesticides. Pesticides are among the group of pollutants that can generate significant impacts on environments in which they are entered, some of which impacts are not yet fully known. Due to the growing demand for food and the consequent need to achieve greater productivity, pesticide use has increased significantly favoring the increase f these impacts. This agricultural production system is prevalent in the world and results in the presence of such pollutants in various aquatic environments, especially the surface regions, near of crop areas. In this context, monitoring of these pollutants in the field indicates its fate in the environment near its application showing more accurately its behavior in field, and provides reference information for program monitoring and evaluation of pesticides in these environments. This study examined samples of water and sediment Piquiri River, located in a region of high production of wheat, soybeans and corn in the state of Paraná, Brazil. This river is under direct influence of the application of pesticides of the region. Water samples were extracted with a mixture of dichloromethane:hexane and sediment samples with acetone:hexane and was concentrated 500 times for water and 25 times for sediment. The extracts were analyzed by LC / MS / MS and confirmed the presence of herbicides and fungicides used in the study region according to official data of the marketing period of the collections. The most impressive results in the water samples were the herbicide Atrazine, 0,030 μg L-1 and the fungicide Carbendazim, 0,178 μg L-1. In the sediment, the highest values were found for the fungicide Carbendazim, 26.8 μg L-1 and Azoxystrobin, 0.712 μg L-1, both in the third collection at the collection point 3.

A qualidade da água e preservação dos ambientes aquáticos assumiu papel fundamental para a sustentabilidade, não só relacionado ao abastecimento, mas também à preservação destes ecossistemas. O uso da água, especialmente para abastecimento dos centros urbanos e irrigação na agricultura tem favorecido a tendência à diminuição das reservas de águas limpas e consequentemente a menor diluição de poluentes presentes, entre eles os pesticidas. Os pesticidas fazem parte do grupo de poluentes que podem gerar impactos significativos nos ambientes em que são inseridos, impactos dos quais alguns ainda não são totalmente conhecidos. Em função do crescente aumento da demanda por alimentos e sua consequente necessidade de se obter maior produtividade, o uso de pesticidas tem aumentado significativamente favorecendo o aumento destes impactos. Este modelo agrícola de produção é predominante em todo o mundo e resulta na presença destes poluentes nos mais diversos ambientes aquáticos, especialmente os superficiais próximos a regiões de cultivo. Neste contexto, o monitoramento destes poluentes em campo indica seu destino nos ambientes próximos à sua aplicação demonstrando mais fielmente seu comportamento neles, bem como fornece informações de referência para programas de monitoramento e avaliação de pesticidas nestes ambientes. O presente estudo avaliou amostras de água e sedimento do Rio Piquiri, localizado em uma região de alta produção de trigo, soja e milho, no estado do Paraná, Brasil. Este rio sofre influência direta da aplicação de pesticidas das lavouras da região. As amostras de água foram extraídas com uma mistura de diclorometano:hexano e as amostras de sedimento com uma mistura de acetona:hexano, tendo sido concentradas 500 vezes para as amostras de água e 25 vezes para as de sedimento. Os extratos foram analisados em LC/MS/MS e confirmaram a presença dos herbicidas e fungicidas utilizados na região do estudo conforme dados oficiais de comercialização no período das coletas. Os resultados mais expressivos nas amostras de água foram do herbicida Atrazina, 0,030 μg L-1 e do fungicida Carbendazim, 0,178 μg L-1. No sedimento os maiores valores encontrados foram para os fungicidas Carbendazim 26,8 μg L-1 e Azoxistrobina, 0,712 μg L-1, ambos na terceira coleta no ponto de coleta 3. / Water quality and conservation of aquatic environments assumed a leading condition for sustainability, not only related to the supply, but also the preservation of these ecosystems. The use of water, especially for supply to urban centers and irrigation in agriculture has favored upon the decrease of the reserves of clean water and therefore less dilution of pollutants, including pesticides. Pesticides are among the group of pollutants that can generate significant impacts on environments in which they are entered, some of which impacts are not yet fully known. Due to the growing demand for food and the consequent need to achieve greater productivity, pesticide use has increased significantly favoring the increase f these impacts. This agricultural production system is prevalent in the world and results in the presence of such pollutants in various aquatic environments, especially the surface regions, near of crop areas. In this context, monitoring of these pollutants in the field indicates its fate in the environment near its application showing more accurately its behavior in field, and provides reference information for program monitoring and evaluation of pesticides in these environments. This study examined samples of water and sediment Piquiri River, located in a region of high production of wheat, soybeans and corn in the state of Paraná, Brazil. This river is under direct influence of the application of pesticides of the region. Water samples were extracted with a mixture of dichloromethane:hexane and sediment samples with acetone:hexane and was concentrated 500 times for water and 25 times for sediment. The extracts were analyzed by LC / MS / MS and confirmed the presence of herbicides and fungicides used in the study region according to official data of the marketing period of the collections. The most impressive results in the water samples were the herbicide Atrazine, 0,030 μg L-1 and the fungicide Carbendazim, 0,178 μg L-1. In the sediment, the highest values were found for the fungicide Carbendazim, 26.8 μg L-1 and Azoxystrobin, 0.712 μg L-1, both in the third collection at the collection point 3.

Este trabalho teve como objetivo principal a utilização de duas variantes da técnica analítica de fluorescência de raios X, dispersiva em energia - EDXRF e reflexão total TXRF, na determinação de Pb em amostras de águas superficiais e subterrâneas, e em sedimentos em suspensão e de fundo. Cinco amostras de cada matriz foram coletadas em uma área contaminada, nas proximidades da desativada fábrica de baterias Indústria Acumuladores Ajax Ltda., localizada no km 229 da rodovia Jaú-Ipaussu, em Bauru, SP. As variantes EDXRF com pré-concentração com APDC e medida direta por TXRF mostraram resultados satisfatórios na determinação de Pb em soluções-padrão e amostra certificada de água natural SRM1640, produzida pelo NIST, obtendo-se concentrações compatíveis com os valores esperados. A primeira técnica resultou em limite de detecção da ordem de 0,70 mg L-1, com tempo de análise de 300 s, melhor que a segunda técnica (4,46 mg L-1), em 200 s. Estas duas variantes também foram utilizadas para outros elementos químicos, como o Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn e Br, onde a EDXRF mostrou também melhores limites de detecção para todos os elementos. Para Ni, Cu e Zn, importantes na indústria de baterias, foram encontrados os limites de 0,34 - 0,27 e 0,24 mg L-1, respectivamente, enquanto que por TXRF foram encontrados os valores ao redor de 1 mg L-1. Na validação destas duas metodologias para análise de água, a EDXRF mostrou resultados mais próximos aos valores esperados, enquanto que por TXRF foram superestimados na maioria das vezes, com exceção para As, Se e Pb. Este erro foi devido a uma interferência espectral ocasionada provavelmente pela presença dos elementos Ti ao Zn nos componentes metálicos do arranjo experimental, ausentes no suporte refletor de quartzo, colimador do detector ou solução do padrão interno. Sem a eliminação dessa interferência, os resultados obtidos por TXRF para estes elementos, com exceção para As, Se e Pb, só podem ser utilizados como qualitativos. Para análise de sedimentos em suspensão foi utilizada a técnica de EDXRF, assumindo a amostra como filme fino, atingindo limite de detecção da ordem de 2 mg g-1 para Pb, enquanto que para o Cu e Zn o limite de detecção foi da ordem de 5 mg g-1, em 300 s. Para sedimento de fundo foi utilizada a mesma técnica, mas admitindo a amostra como espessa, corrigindo-se o efeito matriz através do fator de absorção, validando-a pela análise de amostras certificadas de sedimento (SRM1646a/NIST) e solo (SRM2711/NIST). O limite de detecção para Pb ficou em torno de 2 mg g-1, e para outros elementos os limites foram de 3,07 mg g-1 para Ni, 2,12 mg g-1 para Cu e 1,50 mg g-1 para Zn, em 500 s. Com base nos valores máximos permitidos para Pb, estabelecidos pela Portaria 1469/00 e Resolução 20/1986 CONAMA, duas amostras de água mostraram-se contaminadas pelos resultados obtidos pela variante EDXRF, e quatro pelos resultados da TXRF. Para os outros elementos, apesar da interferência na TXRF, por esta técnica uma amostra de água ultrapassou o limite permissível para Cu e todas as cinco para Zn, e pela EDXRF uma amostra para Ni e Cu em água, e três para Zn. Na legislação brasileira não há limite máximo permitido para Pb e outros elementos em solos e sedimentos, e portanto foram adotados os limites TEL (Threshold Effect Level, nível limiar do efeito) e PEL (Probable Effect Level, nível provável do efeito), utilizados pela Agência Ambiental Canadense. As amostras de sedimento em suspensão mostraram concentrações de Pb menores que o limite de detecção, e das cinco amostras de sedimento de fundo, uma amostra apresentou valor acima do limite TEL, e outra, coletada num ponto bem ao lado da fábrica, acima do limite PEL. Para os outros elementos Ni, Cu e Zn, nenhuma das amostras de sedimento em suspensão ou de fundo não ultrapassaram os limites TEL. / This study had as main objective the use of two variants of the analytical technique of X-ray fluorescence, energy dispersive - EDXRF and total reflection - TXRF, for the determination of Pb in superficial and underground water and in suspended and bottom sediment samples. Five samples of each matrix were collected in a contaminated area near the closed battery plant, Indústria de Acumuladores Ajax Ltd., located on km 229 of the Jaú-Ipaussu highway, near the city of Bauru in São Paulo State, Brazil. The two variants – EDXRF with preconcentration with APDC and TXRF direct measurement – had shown satisfactory results in the determination of Pb in standard solutions and certified natural water sample SRM1640/NIST, obtaining compatible concentrations with the expected values. The first technique resulted in a 0.70 mg L-1 limit of detention, with 300 s analysis time, and the second one 4.46 mg L-1 in 200 s. These two variants were also used for other chemical elements, such as Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn and Br. EDXRF also showed better limits of detection for all the elements. For Ni, Cu and Zn, important in the industry of batteries, the limits of 0.34, 0.27 and 0.24 mg L-1, respectively, were found, while with TXRF the values of around 1 mg L-1 were achieved. In the validation of these two methodologies for water analysis, the EDXRF showed results nearer to the expected values, while with TXRF the results were overestimated most of the times, with the exceptions of As, Se and Pb. This error was due to a spectral interference caused probably by the presence of the elements Ti to Zn in the metallic parts of the experimental arrangement, absent in the quartz reflecting support, detector collimator or internal standard solution. Without the elimination of this interference, the results for TXRF for these elements, with the exceptions of As, Se and Pb, can only be used as qualitative results. For analysis of suspended sediments, the EDXRF technique was used, assuming the sample as thin film, the limit of detection of around 2 mg g-1 for Pb was reached, while that for Cu and Zn was around 5 mg g-1, in 300 s. For bottom sediments the same technique was used, but admitting the sample as thick, the matrix effect through the absorption factor was corrected, validating it for the analysis of certified samples of sediment (SRM1646a/NIST) and soil (SRM2711/NIST). The limit of detention for Pb was around 2 mg g-1 and for other elements the limits were 3.07, 2.12 and 1.50 mg g-1 for Ni, Cu and Zn, respectively, in 500 s. On the basis of the Brazilian allowed maximum values for Pb, established by Decree 1469/00 and Resolution 20/1986 CONAMA, two water samples were shown to be contaminated by the results gotten with variant EDXRF, and four by the results of TXRF. For the other elements from the TXRF results (despite the interference) one water sample exceeded the permissible limit for Cu and all the five for Zn, and for the EDXRF results one sample for Ni and Cu and three for Zn. In the Brazilian legislation there is no maximum limit allowed for Pb and other elements in soils and sediments; therefore, TEL (Threshold Effect Level) and PEL (Probable Effect Level) limits from the Canadian Environment Agency were adopted. The suspended sediment samples showed Pb concentrations lesser than the limit of detection. From the five bottom sediment samples, one sample presented a value above the TEL limit, and another one, collected in a point very close to the plant, above the PEL limit. For the other elements, Ni, Cu and Zn, none of the suspended or bottom sediment samples exceeded the TEL limits.

The connections between surface water and groundwater systems remain poorly understood in many catchments throughout the world and yet they are fundamental to effectively managing water resources. Managing water resources in an integrated manner is not straightforward, particularly if both resources are being utilised, and especially in those regions that suffer problems of data scarcity. This study explores some of the principle issues associated with understanding and practically modelling surface and groundwater interactions. In South Africa, there remains much controversy over the most appropriate type of integrated model to be used and the way forward in terms of the development of the discipline; part of the disagreement stems from the fact that we cannot validate models adequately. This is largely due to traditional forms of model testing having limited power as it is difficult to differentiate between the uncertainties within different model structures, different sets of alternative parameter values and in the input data used to run the model. While model structural uncertainties are important to consider, the uncertainty from input data error together with parameter estimation error are often more significant to the overall residual error, and essential to consider if we want to achieve reliable predictions for water resource decisions. While new philosophies and theories on modelling and results validation have been developed (Beven, 2002; Gupta et al., 2008), in many cases models are not only still being validated and compared using sparse and uncertain datasets, but also expected to produce reliable predictions based on the flawed data. The approach in this study is focused on fundamental understanding of hydrological systems rather than calibration based modelling and promotes the use of all the available 'hard' and 'soft' data together with thoughtful conceptual examination of the processes occurring in an environment to ensure as far as possible that a model is generating sensible results by simulating the correct processes. The first part of the thesis focuses on characterising the 'typical' interaction environments found in South Africa. It was found that many traditional perceptual models are not necessarily applicable to South African conditions, largely due to the relative importance of unsaturated zone processes and the complexity of the dominantly fractured rock environments. The interaction environments were categorised into four main 'types' of environment. These include karst, primary, fractured rock (secondary), and alluvial environments. Processes critical to Integrated Water Resource Management (IWRM) were defined within each interaction type as a guideline to setting a model up to realistically represent the dominant processes in the respective settings. The second part of the thesis addressed the application and evaluation of the modified Pitman model (Hughes, 2004), which allows for surface and groundwater interaction behaviour at the catchment scale to be simulated. The issue is whether, given the different sources of uncertainty in the modelling process, we can differentiate one conceptual flow path from another in trying to refine the understanding and consequently have more faith in model predictions. Seven example catchments were selected from around South Africa to assess whether reliable integrated assessments can be carried out given the existing data. Specific catchment perceptual models were used to identify the critical processes occurring in each setting and the Pitman model was assessed on whether it could represent them (structural uncertainty). The available knowledge of specific environments or catchments was then examined in an attempt to resolve the parameter uncertainty present within each catchment and ensure the subsequent model setup was correctly representing the process understanding as far as possible. The confidence in the quantitative results inevitably varied with the amount and quality of the data available. While the model was deemed to be robust based on the behavioural results obtained in the majority of the case studies, in many cases a quantitative validation of the outputs was just not possible based on the available data. In these cases, the model was judged on its ability to represent the conceptualisation of the processes occurring in the catchments. While the lack of appropriate data means there will always be considerable uncertainty surrounding model validation, it can be argued that improved process understanding in an environment can be used to validate model outcomes to a degree, by assessing whether a model is getting the right results for the right reasons. Many water resource decisions are still made without adequate account being taken of the uncertainties inherent in assessing the response of hydrological systems. Certainly, with all the possible sources of uncertainty in a data scarce country such as South Africa, pure calibration based modelling is unlikely to produce reliable information for water resource managers as it can produce the right results for the wrong reasons. Thus it becomes essential to incorporate conceptual thinking into the modelling process, so that at the very least we are able to conclude that a model generates estimates that are consistent with, and reflect, our understanding (however limited) of the catchment processes. It is fairly clear that achieving the optimum model of a hydrological system may be fraught with difficulty, if not impossible. This makes it very difficult from a practitioner's point of view to decide which model and uncertainty estimation method to use. According to Beven (2009), this may be a transitional problem and in the future it may become clearer as we learn more about how to estimate the uncertainties associated with hydrological systems. Until then, a better understanding of the fundamental and most critical hydrogeological processes should be used to critically test and improve model predictions as far as possible. A major focus of the study was to identify whether the modified Pitman model could provide a practical tool for water resource managers by reliably determining the available water resource. The incorporation of surface and groundwater interaction routines seems to have resulted in a more robust and realistic model of basin hydrology. The overall conclusion is that the model, although simplified, is capable of representing the catchment scale processes that occur under most South African conditions.