Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Water loss in water distribution systems has been studied for many years in many countries and is continuously leading to the development of new concepts and theories, publications, guidelines and software models. Despite these developments, 45 % of water utilities in South Africa still do not understand the extent of water losses in the distribution systems that they operate (Wegelin et al., 2012:27). It is important, in terms of water services planning, that a realistic estimate of the potential savings from individual water conservation and water demand management (WC/WDM) measures is made as it impacts directly on water security and business matters. If the potential savings were incorrectly or inaccurately calculated, additional resources might have to be developed at short notice to be able to supply in the demand. Advanced software models, such as BENCHLEAK, PRESMAC, SANFLOW, AQUALITE and ECONOLEAK (McKenzie & Bhagwan, 2000) have been developed to quantify the extent of physical and commercial losses in water supply systems. Similar advanced models are available for estimating water demand. Such advanced models require numerous input parameters, each of which needs to be described accurately. The predicament is that such complex models are often simply not applicable in certain areas with limited resources and limited input data. In contrast, robust guidelines that are relatively insensitive to input parameters are useful in developing countries, where all input values for complex water demand models may be unavailable or inaccurate. No robust method has yet been developed for estimating the potential water savings that would result from WC/WDM interventions. A need thus exists to estimate water savings in a robust way with relatively few inputs. This guideline promotes the development of a robust WC/WDM strategy, based on a systematic and pragmatic approach, which requires less initial funding and develops with time. The methodologies developed by the Water Loss Task Force (WLTF) of the International Water Association (IWA), were used to develop six basic steps, which need to be followed to develop a WC/WDM strategy. During the six steps, the minimum requirements for implementing WC/WDM will be defined, the current water losses and efficiencies will be determined, and potential targets will be set based on national and international benchmarks. Once targets have been set, 20 key interventions were identified to address water use efficiency, and commercial and physical losses. The motivation behind each intervention is provided based on best practice, case studies and legal requirements. The model ensures that the potential savings from the various interventions are sufficient to ensure that targets are achieved, and if not, that targets must be revised. The potential savings from interventions are based on literature reviews and new formulas developed as part of this guideline. The results from the various interventions would enable the water utility to prioritise interventions. The guideline concludes with a flow diagram describing the methodology.

The need for a more sustainable approach to water consumption has increasingly gained attention in the last decade. The domestic sector accounts for over half of abstracted water in the UK and, as such, has become a major target for water efficiency interventions. Current research and water efficiency interventions are dominated by a positivist approach, focusing on a limited range of factors that can be quantitatively measured. This thesis questions the dominant approach and argues that a more holistic overview of water efficiency can be achieved through the consideration of socio-technical and behavioural theories. Taking a more constructivist approach, this research draws on four theories from socio-technical and behavioural fields and combines them to create a framework for the analysis of water efficiency interventions. The framework is applied to two case studies, exploring water users' perceptions of water, water supply, personal water use, and their responses to the water efficiency interventions. The case studies were selected to provide examples of current mainstream approaches to water demand management. Research methods used included semi-structured interviews and observation. The research findings support the argument that the current dominant approach to domestic water efficiency interventions is limited and, in some cases, ineffectual. Issues of trust, knowledge, motivation and the relationships between water users and water companies were raised. The thesis concludes that the use of a constructivist perspective could help to provide a more effective approach to understanding and improving water demand management.

Outdoor water use by single-family residences in the desert city of Tucson, Arizona is investigated as a multi-scaled coupled human-environment system, using remotely sensed images, GIS data, household water use records and survey responses. Like many desert cities, Tucson's municipal water system faces stresses at multiple spatial and temporal scales: rising demand, limited supplies, competition for distant resources and the likelihood of shortages due to regional climate change. Though the need for demand management is recognized, conflict between the long-term regional scale of the ecosystem that sustains Tucson's water supply and the short-term, local scale of the municipal utility results in a "lack of fit", shown here as the inability to reduce consumption to sustainable levels.While direct regulation of outdoor water use has not been successful, geographic research suggests that modification of the built environment, the focus of the three studies comprising this dissertation, holds promise as a demand management strategy. The first study is a spatial analysis of survey responses on outdoor water use practices during a drought. Next, the potential for substituting common amenities (irrigated landscapes and swimming pools) for private ones is investigated. Residential use was found to be sensitive to park proximity, greenness (proxied by the Normalized Difference Vegetation Index), size and presence of a park pool. Most small parks were net water savers; large parks offered the opportunity to substitute reclaimed water for potable supplies.The last study correlates long-term Landsat-based vegetation and water use trends and integrates these with a spatial analysis of kinetic temperatures. Findings indicate that despite reduced water use, Tucson became greener over the 1995 - 2008 period. This effect is attributed to a pulse of vegetation establishment in response to a shift in the El Niño - Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) around 1976 and to irrigation prior to the study period. I conclude that although the coupled human-environment system of Tucson's municipal water supply and use practices is complex, there are scale-dependent competitive advantages to be gained through thoughtful modification of the built environment.

The demand for water is a very specific variable determined by many factors. The thesis aims to explain how does weather condition influenced the overall character of water demand. Predictions of climate change shows that in terms of CR it can expect changes in total precipitation during the seasons, the increase in average temperatures and a change in the variability and intensity of extreme events. The analysis therefore focuses on clarifying the impact of the level of temperature and precipitation on water withdrawals from public water supply. Analysis used daily data on the collection of water from public water supply for each interested location and daily hydrological data on the level of average daily air temperature and daily rainfall.

O presente trabalho propõe uma evolução metodológica na operação do Sistema Adutor Metropolitano de São Paulo, em tempo real. Foi implantado um modelo matemático, em tempo real, de previsão de consumo de água horário para uma melhoria na performance operacional. Descrevem-se vários procedimentos de sistema de controle operacional, desde manual até totalmente automático, em sistemas de abastecimento. O sistema de abastecimento de São Paulo é classificado neste contexto. Foi analisada a possibilidade de desenvolvimento da situação atual rumo a um controle mais eficiente, através do uso de um modelo de previsão de demanda de água. O “estado da arte" em modelos de previsão de consumo de água é apresentado através de uma revisão bibliográfica especifica. Foi desenvolvida uma interface entre um modelo de rede hidráulica e um modelo de previsão de demanda de água existente, ambos utilizando dados operacionais, obtidos em tempo real de um sistema de telemetria. A interface foi testada em um estudo de caso do Sistema Adutor de São Paulo. Com a utilização de um modelo de previsão, concluiu-se que é possível estabelecer regras operacionais mais eficientes. Essa eficiência é demonstrada pela redução do número de mudanças de posição de válvula e estado de bombas, bem como é observada a redução do custo de energia elétrica (reduzindo o bombeamento em horário de maior custo). Os benefícios obtidos do uso conjunto do modelo simulador hidráulico e do modelo de previsão de demanda não podem ser considerados como o ótimo global. Seria necessário dispor de um modelo de otimização (programação automática). De qualquer forma, foi concluído que o investimento na implementação desses dois modelos é extremamente atrativa. / This work proposes a methodological evolution of a real time water distribution system operation applied to the Water Mains System of Metropolitan Region of Sao Paulo. It was settled a mathematical model in real time, to forecast hourly water consumptions, intending to increase operational performance. Several operational control procedures of water systems were described, since manual ones until total automatic ones. Sao Paulo system is classified into this concept. The possibility of development from the present status toward a more efficient control was analyzed, through the use of a water demand prediction model. State-of-art of water demand models is presented, through a specific literature review. An interface between a hydraulic network model and an existing water demand prediction model were developed both of them using operational data, obtained in real time by a telemetric system. The interface was tested in a case study of Sao Paulo Water Mains System. One concludes that through the use of the prediction model, it was possible to make more efficient operational schedules. This efficiency is demonstrated by the reduction in number of valve positions changes and in pump status changes, as well as a decrease in energy costs could be observed ( reducing pump operations in hours of more expensive costs). Benefits obtained by the conjunctive use of the hydraulic simulation model and the water demand prediction model can not be admitted as the global optimum. It would be necessary to make available an optimization model (automatic scheduler). However it was concluded that investment in these two models implementations is extremely attractive.

O objetivo deste estudo foi quantificar a produtividade de biomassa e energia (parte aérea), bem como a produtividade da água (PA) em 24 variedades de cana-de-açúcar, submetidas à irrigação plena e ao déficit hídrico, durante o estádio de crescimento dos colmos. Foram instalados dois experimentos, em casa de vegetação, na área do Departamento de Engenharia de Biossistemas da ESALQ/USP, Piracicaba, SP. O Experimento-1 avaliou dez variedades de canade- açúcar em solo de textura argilosa (RB835054, RB855453, RB855536, RB925211, RB867515, SP89-1115, SP81-3250, CTC14, CTC8 e CTC6) e o Experimento-2, quatorze variedades em solo de textura franco-arenosa (RB925345, RB855156, RB966928, RB72454, RB92579, IACSP95- 5000, Caiana, SP83-2847, SP90-3414, SP79-1011, CTC17, CTC15, CTC9 e CTC2). Para ambos os experimentos foram adotadas duas formas de manejo da irrigação: T100 - irrigação plena com reposição de 100% da evapotranspiração da cultura (ETc), mantendo-se o solo com umidade próxima a capacidade de campo, e T70 - irrigação com 70% da lâmina de reposição de T100. A diferenciação das irrigações iniciou-se aos 101 dias após o corte (DAC) da cana-planta, correspondendo ao final do perfilhamento intenso e inicio da fase de crescimento dos colmos (1ª soca). Observou-se variação na produtividade da água em biomassa fresca de colmos (PABFC) na ordem de 16,22 a 29,21 kg m-3 em função das variedades e dos manejos de irrigação aplicados. Destacaram-se as variedades CTC6, CTC14, RB867515, SP81-3250 e RB92579, em T100, e as variedades CTC6, CTC14 e SP90-3414, em T70. Em termos de produtividade da água em biomassa de açúcar total recuperável (PABATR), observou-se variação entre 1,95 e 3,84 kg m-3, destacando-se as variedades CTC6 e RB92579 (T100) e as variedades RB835054 e RB966928 (T70). A produtividade da água em biomassa seca total da parte aérea (PABTPA) variou entre 6,98 e 11,94 kg m-3 com destaque para as variedades RB92579 e SP81-3250 (T100), e SP90-3414 e SP81-3250 (T70). Para a produtividade da água em energia total (PATOT), verificou-se variação entre 101,17 e 174,65 MJ m-3, com melhores desempenhos para as variedades SP81-3250, CTC6, CTC17 e RB92579 (T100), e SP90-3414, SP81-3250 e CTC6 (T70). / The purpose of this study was to observe the response on biomass yield and energy (shoot) as well as the water productivity (WP) for 24 sugarcane varieties, subjected to full and deficit irrigation during stalk growth stage. Two experiments were established under greenhouse conditions on Biosystems Engineering Department, ESALQ/USP, Piracicaba, SP. The Experiment - 1 evaluated ten varieties on a clay soil (RB835054, RB855453, RB855536, RB925211, RB867515, SP89-1115, SP81-3250, CTC14, CTC8 e CTC6) and the Experiment - 2, fourteen varieties on a sandy-loam soil (RB925345, RB855156, RB966928, RB72454, RB92579, IACSP95-5000, Caiana, SP83-2847, SP90-3414, SP79-1011, CTC17, CTC15, CTC9 e CTC2). In both experiments were adopted two forms of irrigation management: T100 - full irrigation with 100% crop evapotranspiration replacement, maintaining soil moisture near field capacity, and T70 - irrigation with 70% of water depth applied in T100. The differentiation of irrigations was initiated at 101 days after harvest (DAH) of cane-plant, corresponding to the end of tillering and the beginning of intense stalk growth phase (first ratoon). It was observed variation in water productivity of stalk fresh biomass (WPSFB) from 16.22 to 29.21 kg m-3, according of the varieties and irrigation management applied. The highest values were observed in varieties CTC6, CTC14, RB867515, SP81-3250 and RB92579, full irrigation conditions (T100), and CTC6, CTC14 and SP90-3414, deficit irrigation conditions (T70). The water productivity of total recoverable sugar (WPTRS) ranged from 1.95 to 3.84 kg m-3, highest values were observed in varieties CTC6 and RB92579 (T100), as well as RB835054 e RB966928 (T70). For water productivity of total shoot dry biomass (WPTSDB) ranged from 6.98 to 11.94 kg m-3 with better performance observed in varieties RB92579 and SP81-3250 (T100), as well as SP90-3414 and SP81-3250 (T70). The water productivity of total energy (WPTE) varied from 101.17 to 174.65 MJ m-3 with highest values in varieties SP81-3250, CTC6, CTC17 and RB92579 (T100), as well as SP90-3414, SP81-3250 and CTC6 (T70).

Ao longo dos anos, pesquisadores têm liderado estudos com o objetivo de investigar o perfil de consumo de água em edifícios, os quais contribuem para o conhecimento no que tange ao correto dimensionamento dos sistemas prediais. No contexto dos métodos para a caracterização das solicitações, as rotinas comumente empregadas para a obtenção das vazões de projeto foram, em sua maioria, propostas na metade do século XX. Estes modelos precisam ser revisados e readequados para a realidade de conservação existente atualmente. Nos últimos anos, alguns estudos propuseram modelos de simulação com foco de aplicação em sistemas prediais de distribuição de água, devido ao comportamento aleatório e temporal das solicitações neste tipo de sistema. Neste trabalho foi proposto um modelo de simulação estocástica da demanda de água em edifícios residenciais, que contemplou a modelagem comportamental dos usuários e a interação destes com o sistema, a fim de aperfeiçoar o processo de dimensionamento dos sistemas prediais de distribuição de água. Para isto, foram revisadas as bases teóricas de modelos propostos anteriormente com interesse de identificar aspectos significativos e construir um novo modelo, que mesclou a modelagem comportamental dos usuários e do sistema hidráulico. Para a obtenção dos valores das variáveis intervenientes, foi feita uma consulta em trabalhos dentro do contexto nacional e uma coleta de dados em campo. Os resultados da pesquisa em campo mostraram a correlação entre a rotina dos usuários e o volume de água consumida e um aumento médio de 192% do valor da vazão de projeto obtida pelo Método dos Pesos Relativos quando comparada com as vazões obtidas no medidor dos apartamentos monitorados. Em posse de todos os dados de entrada, foram feitas diferentes simulações que variaram o tipo do chuveiro instalado nos apartamentos. Quando comparadas as vazões obtidas pela simulação e pelo Método dos Pesos Relativos, em todos os componentes do sistema, a redução da vazão de projeto variou entre 4% e 61%. Em termos de consumo de material, a redução ficou entre 25% a 63%. / Over the years, researchers have been conducting studies to investigate the water consumption profile in buildings, which contribute to the knowledge regarding the correct sizing of the building hydraulic systems. In context of the methods for characterization of requests, the routines commonly used to obtain the project flows were mostly proposed in mid-20th-century. These models need to be revised and adapted to nowadays water conservation reality. In recent years, some studies have proposed simulation models with application focus in water distribution systems, due to the random and temporal behavior of the requests in this type of system. In this study, a stochastic simulation model of water demand in residential buildings has been proposed, which contemplated the behavioral modeling of users and their interaction with the system, in order to improve the design process of water distribution systems. For such, the theoretical bases of previously- proposed models for the identification of significant aspects for the construction of a new model were revised, which merged the behavioral modeling of users and the hydraulic system. In order to obtain the values of intervening variables, fieldworks and a review was conducted in papers which treated about the Brazilian context. The results of the data collected on the fieldworks show a correlation between the routine of users and the volume of water consumed. Besides, there was an average increase of 192% in the value of the project flow rate obtained by the Brazilian Standard Method when compared with the flows obtained in the monitored apartments. Considering the input data in the model, different simulations - with several different types of showers installed in the apartments - were made. When comparing the flows obtained by the simulation and the Brazilian Standard Method, in all components of the system, the reduction of the project flow varied between 4% and 61%. In terms of material consumption, the reduction was between 25% and 63%.

O presente trabalho propõe uma evolução metodológica na operação do Sistema Adutor Metropolitano de São Paulo, em tempo real. Foi implantado um modelo matemático, em tempo real, de previsão de consumo de água horário para uma melhoria na performance operacional. Descrevem-se vários procedimentos de sistema de controle operacional, desde manual até totalmente automático, em sistemas de abastecimento. O sistema de abastecimento de São Paulo é classificado neste contexto. Foi analisada a possibilidade de desenvolvimento da situação atual rumo a um controle mais eficiente, através do uso de um modelo de previsão de demanda de água. O “estado da arte” em modelos de previsão de consumo de água é apresentado através de uma revisão bibliográfica especifica. Foi desenvolvida uma interface entre um modelo de rede hidráulica e um modelo de previsão de demanda de água existente, ambos utilizando dados operacionais, obtidos em tempo real de um sistema de telemetria. A interface foi testada em um estudo de caso do Sistema Adutor de São Paulo. Com a utilização de um modelo de previsão, concluiu-se que é possível estabelecer regras operacionais mais eficientes. Essa eficiência é demonstrada pela redução do número de mudanças de posição de válvula e estado de bombas, bem como é observada a redução do custo de energia elétrica (reduzindo o bombeamento em horário de maior custo). Os benefícios obtidos do uso conjunto do modelo simulador hidráulico e do modelo de previsão de demanda não podem ser considerados como o ótimo global. Seria necessário dispor de um modelo de otimização (programação automática). De qualquer forma, foi concluído que o investimento na implementação desses dois modelos é extremamente atrativa. / This work proposes a methodological evolution of a real time water distribution system operation applied to the Water Mains System of Metropolitan Region of Sao Paulo. It was settled a mathematical model in real time, to forecast hourly water consumptions, intending to increase operational performance. Several operational control procedures of water systems were described, since manual ones until total automatic ones. Sao Paulo system is classified into this concept. The possibility of development from the present status toward a more efficient control was analyzed, through the use of a water demand prediction model. State-of-art of water demand models is presented, through a specific literature review. An interface between a hydraulic network model and an existing water demand prediction model were developed both of them using operational data, obtained in real time by a telemetric system. The interface was tested in a case study of Sao Paulo Water Mains System. One concludes that through the use of the prediction model, it was possible to make more efficient operational schedules. This efficiency is demonstrated by the reduction in number of valve positions changes and in pump status changes, as well as a decrease in energy costs could be observed ( reducing pump operations in hours of more expensive costs). Benefits obtained by the conjunctive use of the hydraulic simulation model and the water demand prediction model can not be admitted as the global optimum. It would be necessary to make available an optimization model (automatic scheduler). However it was concluded that investment in these two models implementations is extremely attractive.

Este trabalho de dissertação objetiva uma proposta metodológica para a análise da relação entre cenários futuros de disponibilidade hídrica superficial e demanda hídrica, levando-se em consideração a evolução dos fatores intervenientes à oferta hídrica superficial e à demanda hídrica, segundo a narrativa de cenários tendenciais de propagação dos padrões históricos de evolução destes fatores e a narrativa de cenários alternativos. Esta análise é feita através de um balanço hídrico entre disponibilidade hídrica e demanda hídrica. Esta proposta metodológica é aplicada sobre a região de abrangência da UGRHI do Tietê-Jacaré, e esta aplicação objetiva contribuir para a elaboração do plano da bacia da UGRHI em questão. Os fatores intervenientes à oferta hídrica superficial dizem respeito às variáveis meteorológicas, que influem diretamente no regime de precipitações, e aos padrões estatísticos históricos de evolução das precipitações. Os fatores intervenientes à demanda hídrica dizem respeito às variáveis sócio-econômicas e parâmetros tecnológicos de eficiência dos usos múltiplos dos recursos hídricos. Ambos os cenários, tendenciais e alternativos, narram a evolução destes fatores intervenientes à disponibilidade hídrica superficial e demanda hídrica nas dimensões climática e sócio-econômica. Na dimensão climática são propostos dois cenários de evolução dos fatores intervenientes à disponibilidade hídrica: o cenário climático tendencial (CCT) e o cenário climático alternativo. O cenário CCT é uma propagação futura dos padrões estatísticos históricos de evolução dos regimes de precipitações. Para este cenário são geradas séries sintéticas de precipitação, sobre a região ora em estudo, a partir da aplicação de um modelo estocástico linear. O cenário CCA leva em consideração os efeitos regionais das projeções de mudanças climáticas do cenário A1F (IPCC, 2000) para a região ora em estudo. Para este cenário são inferidos os efeitos da projeção de aumento da temperatura, sobre as séries geradas, através de relações empíricas regionais e conceituais de algumas variáveis meteorológicas que influem sobre o comportamento do regime de precipitações. Para a estimativa da disponibilidade hídrica superficial, segundo os dois cenários climáticos supracitados, foi usado o modelo HEC-HMS 2.1 (USACE) de modelagem e simulação de processos de chuva-vazão. Na dimensão sócio-econômica são propostos dois cenários de evolução dos fatores intervenientes à demanda hídrica: o cenário sócio-econômico tendencial (CSET) e o cenário sócio-econômico alternativo (CSEA). O cenário CSET é uma propagação futura dos padrões estatísticos históricos de evolução dos fatores sócio-econômicos e parâmetros tecnológicos intervenientes à demanda hídrica. O cenário CSEA leva em consideração os efeitos regionais das projeções de mudanças sócio-econômicas do cenário A1F (IPCC, 2000) para a região ora em estudo. Como ferramenta computacional para a estimativa de evolução dos fatores intervenientes à demanda hídrica foi desenvolvido, pelo autor dessa dissertação, o modelo MDSA ( Modelo de Demanda Setorial por Recursos Hídricos) baseado na metodologia do modelo NoWUM (Nordeste Water Use Model) (GAISER, T. et al., 2003). O resultado principal deste trabalho de dissertação foi obtido quando da comparação entre os cenários de disponibilidade hídrica superficial e demanda hídrica. Para todos os cenários comparativos foi constatada a evolução para uma situação crítica da relação entre disponibilidade hídrica superficial e demanda hídrica, principalmente nos períodos de estiagem de chuvas, ou períodos de recessão dos escoamentos superficiais. A ocorrência futura da situação crítica, ou escassez hídrica, varia de acordo com a maior ou menor pressão sobre os recursos hídricos, de acordo com os cenários sócio-econômicos, e de acordo com uma disponibilidade maior ou menor de chuvas sobre a região ora em estudo, de acordo com os cenários climáticos. Embora se possa esperar e seja evidente, de forma intuitiva, a ocorrência da escassez hídrica, a proposta, deste trabalho de dissertação, é a elaboração de uma metodologia, ou conjunto de métodos, para a estimativa quantitativa das variáveis de oferta e disponibilidade e demanda hídrica em todas as dimensões espacial e temporal. / This work aims a methodological proposal for the analysis of future scenarios of surface water availability and water demand, being taken into consideration the evolution of the intervening factors of surface water availability and water demand, according to the narrative of trend scenarios of propagation of the historical standards, and the narrative of alternative scenarios. This methodological proposal is applied on the region of the UGRHI of Tietê-Jacaré, and this objective application is to contribute for the elaboration of the watershed plan of the UGRHI. The intervening factors to superficial water availability concern to the meteorological variables that influence directly in the precipitation regimen and to the historical statistical standards of evolution of precipitations. The intervening factors to the water demand concern to the socioeconomic variables and technological parameters of efficiency of the multiple uses of the water resources. Both scenarios, trend and alternative, tell the evolution of these intervening factors into the superficial water availability and water demand in the climatic and socioeconomic dimensions. In the climatic dimension two scenarios of evolution of the intervening factors to the water availability are considered: the climatic tendency scenario (CCT) and the climatic alternative scenario (CCA). The scenario CCT is a future propagation of the historical statistical standards of evolution of regimes of precipitations. For this scenario synthetic precipitation series are generated, on the region in study, from the application of a linear stochastic model. The scenario CCA takes in consideration the regional effect of the projections of climatic changes of scenario A1F (IPCC, 2000) for the region in study. For this scenario the effect of the projection of increase of the temperature are inferred, on the generated series, through regional and conceptual empirical relations of some meteorological variables that influence on the behavior of the precipitation behavior. For the estimate of the superficial water availability, according to two above-mentioned climatic scenarios, the model HEC-HMS 2,1 (USACE) of modeling and simulation of hydrological processes was used. In the socioeconomic dimension two scenarios of evolution of the intervening factor to the water demand are considered: the tendency socioeconomic scenario (CSET) and alternative socioeconomic scenario (CSEA). Scenario CSET is a future propagation of the historical statistical standards of evolution of the socioeconomic factors and intervening technological parameters to the water demand. Scenario CSEA takes in consideration the regional affect of the projections of socioeconomic changes of scenario A1F (IPCC, 2000) for the region in study. As a computational tool for the estimate of the evolution of the intervening factors to the water demand it was developed the MDSA model (Model of Sectorial Demand for Water Resources) based in the methodology of the NoWUM model (Northeast Water Use Model) (GAISER, T. et al.). The main result of this work was gotten when of the comparison between the scenarios of superficial water availability and water demand. For all the comparative scenarios were evidenced the evolution for a critical situation of the relation between superficial water availability and water demand, mainly in the periods of no rains, or periods of contraction of the superficial drainings. The future occurrence of the critical situation, or water scarcity, varies in accordance to the greater or minor pressure on the water resources, in accordance with the socioeconomic scenarios, and in accordance with a bigger or lesser availability of rains on the region in study, in accordance with the climatic scenarios. Although if it can wait and either evident the occurrence of the water scarcity, the proposal, of this work, is the elaboration of a methodology, or set of methods, for the quantitative estimate of the variable of availability and water demand in all the space and temporal dimensions.

The primary question that the thesis investigates is: what impacts could climate change have on cattle water demand and supply in Khurutshe, Botswana. This thesis is pursued in light of the fact that there is a lack of knowledge on climate change and cattle water demand and supply. Thus, this thesis aims at filling the gap in knowledge on climate change and cattle water resources in Botswana and other semi-arid environments. A cattle water demand and supply model is developed to investigate the primary question of the thesis. The model is driven by rainfall and temperature over time as these variables largely determine cattle water supply and demand, respectively. Climate scenarios for 2050 are constructed using SimCLIM (developed by the International Global Change Institute of the University of Waikato) based on HadCM3 and CSIRO Mk2 General Circulation Models (GCMs). Three Special Report on Emission Scenarios (SRES) are used: A1B, A1FT and A1T. These emission scenarios were selected based on their coverage for possible future Greenhouse Gas emissions (GHG). Climate scenarios show that by 2050 the temperature for the Khurutshe area could increase by as much as 3 oC depending on the GCM and SRES emission scenario and that there could be a decline in rainfall of up to 14% per month. CSIRO Mk2 displayed the maximum decline in rainfall while HadCM3 depicted the maximum increase in temperature. The model is implemented in the Khurutshe of the Kgatleng District, Botswana. The results reported are for Masama Ranch and also for the whole of the Khurutshe area. The results show that climate change could lead to an annual increase of more than 20% in cattle water demand by 2050 due to an increase in temperature. In addition, climate change could lead to a decline in the contribution of surface pan water to cattle water supply. Overall, there could be an increase in abstraction of groundwater for cattle by 2050 due to an increase in demand and a decline in forage water content and surface pan water. Observations in semi-arid environments of Africa indicate that farmers encounter problems of declining borehole yields and local depletion in groundwater in summer and drought years when demand peaks. In addition, it has been observed that during drought more cattle are lost as a result of lack of water, particularly for those whose cattle are reliant on surface water. Thus, the results from this study indicate that climate change could enhance this problem. In the thesis I have shown the importance of integrating climate change impacts on water demand and supply when assessing water resources, which has been ignored in the past. Some of the policy options that are discussed are tradable pumping permits for controlling abstraction and allocation issues in the Khurutshe aquifer and, controlling stocking numbers. This is in recognition of the fact that climate change could result in more reliance on groundwater for both cattle farming and urban water supply hence compromising sustainability and allocation issues especially for the Khurutshe aquifer which is earmarked to supply the city of Gaborone and surrounding villages in drought periods.