The study investigates the contribution of WDM towards mitigating scarcity of potable water in cities with particular reference to Bulawayo.WDM origins and its successes are traced. The study classifies scarcity representations into four categories and reveals that the scarcity in Bulawayo satisfies all the four representations hence calls it total scarcity. The research employed document study, questionnaires, interviews and a focus group to collect data. Document study revealed that water restrictions successfully mitigate the scarcity in Bulawayo. Field work partially confirmed the usefulness of WDM in the life of the city and revealed the need to synchronize the conceptualizations of WDM among different stakeholders in order for the paradigm to do even more in terms of mitigating scarcity. The results were interpreted in terms of TPB. The key recommendation of the study is that the city invests in water use behaviour change in order to realise huge water savings. / Development Studies / M.A. (Development Studies)

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The focus of the study is to theoretically assess tank-water demand and employ methods to establish the actual tank-water demand at selected houses in a case study area. This study also examines the influence of domestic rainwater harvesting systems when used in combination with a municipal water distribution system. The case study comprises of 410 low cost housing units in the Western Cape. The system demand patterns of low cost housing units are uncharacteristic, when compared with suburban system demand patterns, and cannot be defined by traditional models. Similarly, the use of rainwater harvesting systems in these areas follows an unconventional routine that is yet to be defined. A stochastic end-use model for water demand is developed which produces temporal profiles for water supplied from both sources, namely the water distribution system and the rainwater harvesting system. The model approximates a daily system and tank-water demand pattern for a single domestic household, using @RISK software. The demand estimation methodology is clarified through application on a particular case study site where harvested rainwater is frequently utilized. Estimates of the parameter values are based on consumer surveys and previous studies on the case study area, where the household size was defined in the form of a probability distribution. The results confirm the atypical system demand patterns in low cost housing units units. Although two clear peaks exist in the morning and in the evening, a relatively constant average flow is present throughout the day. A sensitivity analysis of all the model parameters verified that the household size has the most substantial influence on the tank-water demand pattern. The system and tank-water demand patterns were compared to published average daily water demand guidelines, which confirmed that increased water savings could be achieved when the rainwater source is accessible inside the household with minimal effort. The stochastic demand profiles derived as part of this research agree with the metered system demand in the same area. The results of this study could be incorporated into the future development of national standards. / AFRIKAANSE OPSOMMING: Die fokus van die studie is om die tenkwater-aanvraag teoreties te ontleed en metodes in werking te stel om die werklike tenkwater-aanvraag vas te stel by geselekteerde huise in ‘n gevallestudie area. Hierdie studie ondersoek ook die invloed van plaaslike reënwater-herwinningstelsels wanneer dit gebruik word in kombinasie met ‘n munisipale waterverspreidingstelsel. Die gevallestudie bestaan uit 410 laekoste behuisingseenhede in die Wes-Kaap. Die stelsel-aanvraagpatrone van laekoste behuisingseenhede is verskillend wanneer dit met voorstedelike stelsel-aanvraagpatrone vergelyk word en kan nie gedefinieer word deur tradisionele modelle nie. Soortgelyk volg die gebruik van reënwater-herwinningstelsels in hierdie areas ‘n onkonvensionele roetine. ‘n Stogastiese eindgebruikmodel vir water-aanvraag is ontwikkel, wat tydelike profiele genereer vir water wat van beide bronne verskaf word, naamlik die waterverspreidingstelsel en die reënwater-herwinningstelsel. Die model bepaal by benadering ‘n daaglikse stelsel- en tenkwater-aanvraagpatroon vir ‘n enkele plaaslike huishouding, deur @RISK sagteware. Die aanvraag-beramingstegnieke word verduidelik deur toepassing op ‘n spesifieke gevallestudie, waar herwinde reënwater gereeld gebruik word. Die parameter waardeberamings is gebaseer op verbruikers-opnames en vorige studies oor die gevallestudie-gebied, waar die grootte van die huishoudings bepaal was in die vorm van 'n waarskynlikheidsverspreiding. Die resultate bevestig die atipiese stesel aanvraagpatrone in laekoste behuisingseenhede eenhede. Alhoewel twee duidelike pieke in die oggend en die aand voorkom, is ‘n relatiewe konstante vloei dwarsdeur die dag teenwoordig. ‘n Sensitiwiteitsanalise van al die modelparameters bevestig dat die grootte van die huishouding die grootste beduidende invloed op tenkwater- aanvraagpatrone het. Die stelsel- en tenkwater-aanvraagpatrone was vergelyk met gepubliseerde gemiddelde daaglikse water-aanvraag riglyne wat bevestig dat meer waterbesparings bereik kan word waar die reënwaterbron binne die huishouding beskikbaar is met minimale moeite. Die stogastiese aanvraagprofiele, wat as deel van hierdie navorsing afgelei was, stem saam met die gemeterde stelsel-aanvraagpatroon van dieselfde area. Die resultate van hierdie studie kan in die toekomstige ontwikkeling van nasionale standaarde opgeneem word.

nÃo hà / This paper aims to estimate a residential water demand function for the city of Fortaleza (CearÃ), considering the potential impact of the spatial effects on water consumption. The analysis is developed from the investigation of presence of spatial autocorrelation in residential water consumption. For this, the tools of exploratory spatial data analysis (ESDA) were utilized. Subsequently, specific tests are performed to determine the sources of spatial autocorrelation, i.e., if the autocorrelation is caused by the spatial distribution of water consumption or by effects not modeled. Identified the sources of spatial autocorrelation, four water demand functions were estimated, which had as explanatory variables the average price, the difference, income, number of residents and the number of rooms, under different specifications. At first, we estimated a model without special effects; in the second, we estimated the specification of the spatial error model (SEM), which incorporates the spatial autocorrelation in the form of autocorrelation in the error terms; in the third, we estimated the spatial autoregressive model (SAR), where the spatial autocorrelation is incorporated through the spatial lag of the dependent variable; and finally, we estimated the spatial model autoregressive moving average (SARMA), which is the union of the two previous models. The results show that spatial autocorrelation exists in two forms (error and lag), indicating that the SARMA model is the most indicated to model the residential water demand in the city of Fortaleza, in contrast to suggested by Chang et al.(2010), House-Peters et al. (2010), Franczyk e Chang (2008), Ramachandran e Johnston (2011), which used the SEM model. It is concluded that it is important to consider the possibility of spatial effects in the estimation of a residential water demand function, once that not incorporate spatial effects in the analysis underestimate the effect of the variables average price and number of residents on residential water demand, while overestimating the effect of the variables income and number of rooms. / Esta dissertaÃÃo tem como objetivo estimar uma funÃÃo de demanda residencial por Ãgua para a cidade de Fortaleza (CearÃ), considerando o provÃvel impacto do efeito espacial no consumo de Ãgua. A anÃlise se desenvolve a partir da investigaÃÃo a respeito da presenÃa de autocorrelaÃÃo espacial no consumo residencial de Ãgua. Para tal, foram utilizadas as tÃcnicas de anÃlise exploratÃria espacial de dados (ESDA). Posteriormente, sÃo realizados testes especÃficos para determinar as fontes da autocorrelaÃÃo espacial, ou seja, identificar se a autocorrelaÃÃo à causada pela distribuiÃÃo espacial do consumo de Ãgua ou pelos efeitos nÃo modelados. Identificadas as fontes de autocorrelaÃÃo espacial, foram estimadas quatro funÃÃes de demanda de Ãgua, que tinham como variÃveis explicativas o preÃo mÃdio, a diferenÃa, a renda, o nÃmero de residentes e o nÃmero de cÃmodos, sob diferentes especificaÃÃes. Na primeira, utilizou-se um modelo sem efeitos espaciais; na segunda, utilizou-se a especificaÃÃo do modelo de erros espaciais (SEM), que incorpora a autocorrelaÃÃo espacial na forma de autocorrelaÃÃo nos termos de erro; na terceira, utilizou-se o modelo espacial autorregressivo (SAR), onde a autocorrelaÃÃo espacial à incorporada atravÃs da defasagem espacial da variÃvel dependente; e por Ãltimo, utilizou-se o modelo espacial autorregressivo de mÃdias mÃveis (SARMA), que à a uniÃo dos dois modelos anteriores. Os resultados mostram que existe autocorrelaÃÃo espacial nas duas formas (erro e defasagem), indicando que o modelo SARMA à o mais adequado para modelar a demanda residencial por Ãgua na cidade de Fortaleza, ao contrÃrio do proposto por Chang et al. (2010), House-Peters et al. (2010), Franczyk e Chang (2008), Ramachandran e Johnston (2011), que utilizaram o modelo SEM. Conclui-se, portanto, que à importante levar em consideraÃÃo a possibilidade de efeitos espaciais na estimaÃÃo de uma funÃÃo de demanda residencial por Ãgua, na medida que a nÃo incorporaÃÃo dos efeitos espaciais subestima o efeito das variÃveis preÃo mÃdio e nÃmero de residentes sobre a quantidade consumida de Ãgua, enquanto superestima o efeito das variÃveis renda e nÃmero de cÃmodos.

Der Gegenstand des Projektes SAPHIR war die Untersuchung von Trockenstress, Wasserproduktivität und Bewässerungsbedarf landwirtschaftlicher und gemüsebaulicher Nutzpflanzen mit Hilfe von Bewässerungsexperimenten und Simulationswerkzeugen (virtuelles Feld). Das Hauptziel war die Bereitstellung relevanter Informationen, Schlußfolgerungen und Handlungsoptionen für wesentliche Akteure (Landwirte und Entscheidungsträger auf regionaler Ebene) aus der sächsischen Landwirtschaft. Einen einfachen Zugang zu den entwickelten Werkzeugen und Ergebnissen liefert ein webbasiertes Entscheidungshilfesystem mit maßgeschneiderten Schnittstellen für die verschiedenen Akteure, dass die Ermittlung der Bewässerungswürdigkeit beliebiger Standorte und angepasster Anbaumuster für Sachsen für gegenwärtige und zukünftige Klimabedingungen ermöglicht. Die Bestimmung der dafür wichtigen Datengrundlagen, nämlich kulturspezifische Ertragskurven erfolgte auf zwei Wegen: durch konkrete Feldversuche sowie simulationsbasierte Optimierung. Durch die Verwendung von prognostischen Simulationsmodellen ist die Übertragung der Ergebnisse auf andere klimatische Standorte möglich und wurde wird zur Zeit für die Vereinigte Arabische Emirate und den Oman erprobt. Im Rahmen von SAPHIR fand eine intensive Qualifizierung der Nachwuchsforscher statt. Dies umfaßte nicht nur eine umfassende Vermittlung von Spezialwissen über Bewässerungslandwirtschaft inklusive der Teilkomponenten Messung, Modellierung, Analyse und Darstellung sondern auch der Erwerb von Fähigkeiten in Projektmanagement und Kommunikation für eine erfolgreiche Zusammenarbeit innerhalb der interdisziplinär zusammengesetzten Forschergruppe. Die von uns durchgeführten Arbeiten erfolgten in zwei grundsätzlichen Richtungen. Zum einen entwickelten wir die Werkzeuge zur Entscheidungshilfe in der Reihenfolge: experimentelle Untersuchung → Modellierung und Simulation des Bewässerungssystems → simulationsbasierte Optimierung des Bewässerungssystems → Mikro- und Makroökonomische Bewertung und Optimierung. Zum anderen wurden die Arbeiten auf unterschiedlichen räumlichen Skalen durchgeführt: Mikroskala, Feldskala, Betriebsebene sowie regionale (Meso-) Skala.

Desalination technology provides fresh water to the arid regions around the world. Multi-Stage Flash (MSF) distillation process has been used for many years and is now the largest sector in the desalination industry. Top Brine Temperature (TBT) (boiling point temperature of the feed seawater in the first stage of the process) is one of the many important parameters that affect optimal design and operation of MSF processes. For a given pressure, TBT is a function of Boiling Point Temperature (BPT) at zero salinity and Temperature Elevation (TE) due to salinity. Modelling plays an important role in simulation, optimisation and control of MSF processes and within the model, calculation of TE is therefore important for each stages (including the first stage, which determines the TBT). Firstly, in this work, several Neural Network (NN) based correlations for predicting TE are developed. It is found that the NN based correlations can predict the experimental TE very closely. Also predictions of TE by the NN based correlations were found to be good when compared to those obtained using the existing correlations from the literature. Secondly, a hybrid steady state MSF process model is developed using gPROMS modelling tool embedding the NN based correlation. gPROMS provides an easy and flexible platform to build a process flowsheet graphically. Here a Master Model connecting (automatically) the individual unit model (brine heater, stages, etc.) equations is developed which is used repeatedly during simulation and optimisation. The model is validated against published results. Seawater is the main source raw material for MSF processes and is subject to seasonal temperature variation. With fixed design the model is then used to study the effect of a number of parameters (e.g. seawater and steam temperature) on the freshwater production rate. It is observed that, the variation in the parameters affect the rate of production of fresh water. How the design and operation are to be adjusted to maintain a fixed demand of fresh water through out the year (with changing seawater temperature) is also investigated via repetitive simulation. Thirdly, with clear understanding of the interaction of design and operating parameters, simultaneous optimisation of design and operating parameters of MSF process is considered via the application MINLP technique within gPROMS. Two types of optimisation problems are considered: (a) For a fixed fresh water demand throughout the year, the external heat input (a measure of operating cost) to the process is minimised; (b) For different fresh water demand throughout the year and with seasonal variation of seawater temperature, the total annualised cost of desalination is minimised. It is found that seasonal variation in seawater temperature results in significant variation in design and some of the operating parameters but with minimum variation in process temperatures. The results also reveal the possibility of designing stand-alone flash stages which would offer flexible scheduling in terms of the connection of various units (to build up the process) and efficient maintenance of the units throughout the year as the weather condition changes. In addition, operation at low temperatures throughout the year will reduce design and operating costs in terms of low temperature materials of construction and reduced amount of anti-scaling and anti-corrosion agents. Finally, an attempt was made to develop a hybrid dynamic MSF process model incorporating NN based correlation for TE. The model was validated at steady state condition using the data from the literature. Dynamic simulation with step changes in seawater and steam temperature was carried out to match the predictions by the steady state model. Dynamic optimisation problem is then formulated for the MSF process, subjected to seawater temperature change (up and down) over a period of six hours, to maximise a performance ratio by optimising the brine heater steam temperature while maintaining a fixed water demand.

An accurate model for RO process has significant importance in the simulation and optimization proposes. A steady state model of RO process is developed based on solution diffusion theory to describe the permeation through membrane and thin film approach is used to describe the concentration polarization. The model is validated against the operation data reported in the literature. For the sake of clear understanding of the interaction of feed temperature and salinity on the design and operation of RO based desalination systems, simultaneous optimization of design and operation of RO network is investigated based on two-stage RO superstructure via MINLP approach. Different cases with several feed concentrations and seasonal variation of seawater temperature are presented. Also, the possibility of flexible scheduling in terms of the number of membrane modules required in operation in high and low temperature seasons is investigated A simultaneous modelling and optimization method for RO system including boron removal is then presented. A superstructure of the RO network is developed based on double pass RO network (two-stage seawater pass and one-stage brackish water pass). The MINLP problem based on the superstructure is used to find out an optimal RO network which will minimize the total annualized cost while fulfilling a given boron content limit. The effect of pH on boron rejection is investigated at deferent seawater temperatures. The optimal operation policy of RO system is then studied in this work considering variations in freshwater demand and with changing seawater temperature throughout the day. A storage tank is added to the RO layout to provide additional operational flexibility and to ensure the availability of freshwater at all times. Two optimization problems are solved incorporating two seawater temperature profiles, representing summer and winter seasons. The possibility of flexible scheduling of cleaning and maintenance of membrane modules is investigated. Then, the optimal design and operation of RO process is studied in the presence of membrane fouling and including several operational variations such as variable seawater temperature. The cleaning schedule of single stage RO process is formulated as MINLP problem using spiral wound modules. NNs based correlation has been developed based on the actual fouling data which can be used for estimating the permeability decline factors. The correlation based on actual data to predict the annual seawater temperature profile is also incorporated in the model. The proposed optimization procedure identified simultaneously the optimal maintenance schedule of RO network including its design parameters and operating policy. The steady state model of RO process is used to study the sensitivity of different operating and design parameters on the plant performance. A non-linear optimization problem is formulated to minimize specific energy consumption at fixed product flow rate and quality while optimizing the design and operating parameters. Then the MINLP formulation is used to find the optimal designs of RO layout for brackish water desalination. A variable fouling profile along the membrane stages is introduced to see how the network design and operation of the RO system are to be adjusted Finally, a preliminary control strategy for RO process is developed based on PID control algorithm and a first order transfer function (presented in the Appendix).

O presente trabalho propõe um modelo de operação sustentado por um sistema de suporte à decisão para operar a distribuição de água em tempo real atendendo a condições / restrições hidráulicas com o mínimo custo de energia elétrica. O atendimento às condições / restrições hidráulicas são avaliadas por um modelo simulador hidráulico previamente montado e calibrado. O conjunto de resultados avaliados pelo modelo de simulação hidráulica é analisado por um modelo de otimização proposto com solução de programação linear. As condições de operação em tempo real geram a necessidade de alimentação de informações operacionais automáticas a qualquer momento e com curto espaço de tempo – menor que horário. Para uma operação otimizada, previamente analisada por um modelo de simulação hidráulica cria uma condição critérios para uma previsão do consumo a ser atendido nas próximas horas. Um refinamento desses critérios são utilizados em um modelo de previsão de demanda de água que prevê e checa seus resultados de forma dinâmica. O modelo de operação proposto cria uma interface entre todos esses sistemas. Essa interface é testada e avaliada a partir de um estudo de caso aplicado no Sistema Adutor Metropolitano de São Paulo. A eficiência do modelo de operação proposto é apresentada tendo como resultado uma redução no custo de energia elétrica. / This assignment considers an operation model supported by decision support systems to operates the water supply systems in real time, considering the hydraulical conditions while achieving some performance goals, in this case, reducing electricity costs (minimization of pumping costs) the attempt of the hydraulic constraints are evaluated by an hydraulical simulator previously calibrated. The set of results are analyzed by an optimization model which uses a linear programming. The operation conditions in real time requires automatic feeding operational information shortly at any time (less than an hour) for an optimized operation, previously analyzed by a hydraulic simulation model with creates condition criteria of consumption within following hours. These criteria are refined according to a demand prediction model that dynamically previews and checks the consumption results. This proposed model creates an interface between all these systems. This interface is tested and evaluated according to a study of the São Paulo´s metropolitan area, “Sistema Alto Tietê". The efficiency of this proposed model is presented having reductions in the electric energy costs.

No contexto da crescente problemática da água, soluções em diferentes níveis têm sido adotadas no Brasil e no mundo. Exemplo de atuação no nível dos sistemas prediais, o uso racional da água tem sido objeto de diversos estudos. Neste trabalho, são avaliados, segundo uma abordagem sistêmica, as atividades a serem contempladas na implementação de Programas Permanentes de Uso Racional da Água, especialmente em campi universitários, e seus potenciais resultados. Características dos campi como área, número de edificações, população e consumo de água elevados, além do desenvolvimento de múltiplas atividades, demonstram sua importância e justificam a atenção. São avaliadas, portanto, as atividades de planejamento, pré-implantação, implantação e pós-implantação, além das atividades de gestão da demanda de água, que devem permear todo o Programa. Como resultado desta implementação estruturada, propõe-se, como impactos - a redução do consumo de água, e como efeitos - alterações no sistema de suprimento de água fria, em rotinas administrativas e de manutenção predial, e em parâmetros de projeto; desenvolvimento tecnológico dos equipamentos; despertar para a conservação da água; e mudanças comportamentais dos usuários. A implementação e os resultados do Programa de Uso Racional da Água da Universidade de São Paulo (PURA-USP) completam o trabalho. Em desenvolvimento desde 1998, o PURA-USP obteve, como impactos até 2003, uma redução no consumo de água de 36% (de 137.881 para 88.366 m³/mês) e um benefício líquido acumulado de R$ 46,61 milhões. / In the context of the increasing water issues concerns, solutions at different levels have been adopted in Brazil and worldwide. As an example of actuation at the building systems level, water conservation has been the object of several studies. In this work, the activities to be fulfilled in the implementation of a Permanent Water Conservation Program, specially when applied to university campi, as well as the possible results are evaluated under a system approach. Campi characteristics such as area, number of buildings, population, and high water consumption, besides the development of multiple activities, show the importance of this issue and justify the concerns. The Program planning, pre-implantation, implantation and post-implantation activities, besides the water demand management activities - that must be carried out throughout the program - are evaluated then. As results of this structured implementation, it is proposed as impacts - the water consumption reduction, and as effects - the changes in the water supply systems, in administrative and building maintenance routines, in design parameters, in the technological development of fixtures, in the awakening for the alternatives water sources, and in the users behavior. The implementation and the results of the Water Conservation Program of the University of São Paulo (Programa de Uso Racional da Água da Universidade de São Paulo - PURA-USP) finish the work. The PURA-USP, in development since 1998, achieved as impacts, until 2003, 36% of water consumption reduction (from 137,881 to 88,366 m³/month) and gathered net benefit of US$ 16.13 millions (R$ 46,61 milhões).

No presente trabalho é estudada a utilização da medição setorizada como instrumento de gestão da demanda de água em sistemas prediais. Para tanto, a caracterização dos medidores e a análise das interações dos elementos de medição com o sistema de suprimento de água fria e de equipamento sanitário são realizados a partir de um enfoque sistêmico e de desempenho. Considerando a coleta de melhores informações, qualitativamente e quantitativamente acerca do consumo, essencial para a gestão da demanda de água, e especialmente em um contexto de ações de conservação, neste trabalho levantou-se os sistemas de telemedição. Apresentou-se uma proposta de planejamento de implantação da medição setorizada e quais elementos que devem ser observados para a gestão da demanda. Para subsidiar as avaliações, realizou-se o estudo de caso da medição setorizada na Universidade de São Paulo, no qual foi possível verificar a importância da sua aplicação e os resultados extremamente positivos que justificaram sua implantação. / In this work it is studied the use of submetering as an instrument of water demand management in building systems. In such way, the characterization of the meters and the analysis of the interactions of its elements with the building hydraulical system are carried on a systemic approach and performance analysis of the proposal. Considering the collection of better information of water consumption essential for the water demand management, especially in a conservation context, it was searched out the systems and the technologies of remote metering. A proposal for the planning of the submetering implantation was showed, as well as the elements that should be considered for the demand management. To make the evaluations, the case study of the submetering program in the University of São Paulo was accomplished, in which it was possible to verify the importance of its application and the extremely positive results that had justified its implantation.

O cimento está entre os materiais mais utilizados no mundo moderno e sua produção deverá crescer nos próximos 40 anos. Esta crescente produção será responsável pela emissão de um grande volume de CO2 na atmosfera, atualmente a indústria cimenteira é responsável mundialmente por 10% das emissões totais de CO2 e pode chegar a 30% em 2050. Portanto, a academia e a indústria estão desenvolvendo estratégias para reduzir este impacto ambiental, uma dessas estratégias é a substituição do clínquer por materiais cimentícios suplementares (MCSs). Para esta estratégia ser efetiva é necessário que estes materiais possuam: (i) viabilidade econômica; (ii) disponibilidade e; (iii) viabilidade técnica. Hoje os materiais suplementares mais utilizados são a escória de alto forno e a cinza volante, mas o aumento na produção do cimento não foi acompanhado pela oferta destes materiais. Assim, outros materiais suplementares estão sendo utilizados pela indústria, como é o caso das pozolanas naturais e artificiais. Portanto o objetivo deste trabalho é estimar a disponibilidade e distribuição geográfica de alguns materiais cimentícios suplementares no Brasil e avaliar a eficiência de seis cimentos pozolânicos comerciais e compará-los com um cimento com alto teor de clínquer quanto a reatividade, demanda de água e indicadores ambientais. Todos os materiais foram fisicamente e quimicamente caracterizados; pastas e argamassas foram analisadas em termos de reatividade, demanda de água e resistência mecânica; finalmente, foram estimados indicadores ambientais e de eficiência. Para pastas e argamassas sem dispersante o cimento com alto teor de clínquer e aqueles com adição de terra diatomácea demandaram mais água que os demais para um mesmo espalhamento, já com adição de superplastificante o cimento REF foi o que demandou mais água. O cimento com alto teor de clínquer foi o mais reativo em todas as idades e apresentou os melhores resultados do indicador de fração de água combinada e indicador de intensidade de ligante. Já para o indicador intensidade de carbono os melhores resultados foram obtidos para os cimentos com alto teor de substituição. No entanto, o estudo mostra que a redução do teor de clínquer não está diretamente relacionada à redução do impacto ambiental do cimento em seu uso, esta redução de impacto também está associada com a eficiência do ligante quanto a sua reatividade e demanda de água. / The cement is one of the most used materials in the modern world and its production should grow in the next 40 years. This growing production will be responsible for issuing a large volume of CO2 on the atmosphere, nowadays the cement industry is responsible worldwide for 10% of the total emissions of CO2 and it can reach 30% in 2050. Therefore, academia and industry are developing strategies to reduce this environmental impact, one of these strategies is the substitution of clinker by supplementary cementitious materials (SCMs). For this strategy to be effective it is necessary that these materials possess: (i) economic viability; (ii) availability and; (iii) technical feasibility. Today the most used supplementary materials are the blast furnace slag and fly ash, but the increase in the production of cement was not accompanied by the supply of these materials. Therefore, other supplementary materials are being used by the industry, as is the case of natural and artificial pozzolans. So, the aim of this work is to estimate the availability and geographic distribution of some supplementary cementitious materials in Brazil and evaluate the efficiency of six Portland pozzolan blended cements and compare them with a cement with high clinker content as to reactivity, water demand and environmental indicators. All materials were physically and chemically characterized; pastes and mortars were analyzed in terms of reactivity, water demand and mechanical strength; finally, environmental and efficiency indicators were estimated. For pastes and mortars without dispersant the cement with high content of clinker and those with the addition of diatomaceous earth ordered more water than the others to achieve the same spread, already with the addition of superplasticizer the cement REF was the one that ordered more water than the others. The cement with high clinker content was the most reactive in all ages and presented the best results of the binder efficiency indicator and binder intensity indicator. For the carbon intensity indicator, the best results were obtained for cements with high replacement content. However, the study shows that the reduction of the clinker content is not directly related to the reduction of the environmental impact of the cement in its use, this reduction is also associated with the binder efficiency in means of reactivity and water demand.