Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. Thus, I used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (CTmax) in urban ants—specifically, that (1) body size, (2) hydration status, and (3) preferred micro-environments influence CTmax. I further tested a fourth hypothesis that native species are particularly physiologically vulnerable in urban environments. I manipulated water access and determined CTmax for 11 species common to cities in California's Central Valley that exhibit nearly 300-fold variation in body mass. Inter- (but not intra-) specific variation in body size influenced CTmax where larger species had higher CTmax. The sensitivity of ants’ CTmax to water availability exhibited species-specific thresholds where short-term water limitation (8 h) reduced CTmax in some species while longer-term water limitation (32 h) was required to reduce CTmax in other species. However, CTmax was not influenced by the preferred foraging temperatures of ants. Further, I did not find support for my fourth hypothesis because native species did not exhibit reduced thermal safety margins, or exhibit CTmax values that were more sensitive to water limitation relative to non-native species. In sum, understanding the links between heat tolerance and water availability will become critically important in an increasingly warm, dry, and urbanized world that may be selecting for smaller (not larger) body size.

The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.

Parametrizações mecanísticas descrevem fisicamente a interação das plantas com o ambiente baseando-se em processos fundamentais, como assimilação de líquida de CO2 e extração da água do solo pelas raízes, influenciados pelas condições do ambiente. O objetivo principal dessas rotinas é aumentar o entendimento do sistema estudado pela integração quantitativa e qualitativa do conhecimento em um modelo de simulação dinâmica do sistema real. Definindo estresse hídrico como a condição em que uma planta aumenta a resistência estomática em conseqüência do aumento da demanda atmosférica e/ou da redução da disponibilidade hídrica no solo, tem-se como hipótese que o déficit hídrico em plantas é causado por fatores ambientais relacionados com as interfaces solo-raiz e folha-atmosfera. O objetivo geral desse estudo é identificar quais são as variáveis do solo e da atmosfera determinantes e que devem ser consideradas na modelagem da deficiência hídrica em plantas. Os teores de água no solo e na atmosfera foram monitorados em condições de campo durante o desenvolvimento da cultura de feijão (Phaseolus vulgaris L.) entre Junho e Setembro de 2010, e correlacionados ao estresse hídrico caracterizado por medições de temperatura do dossel. As variáveis de interesse, especificamente o potencial matricial da água do solo, a temperatura e a umidade do ar e a temperatura do dossel foram medidas regularmente em intervalos de 30 minutos. A taxa de transpiração e a condutância estomática foram medidas ocasionalmente. Uma parcela foi irrigada durante todo o ciclo da cultura (tratamento totalmente irrigada), enquanto a outra foi submetida ao estresse hídrico na fase reprodutiva (tratamento com déficit de irrigação). A metodologia utilizada neste estudo deu suporte à hipótese inicial. Os principais fatores relacionados à interface solo-raiz são as propriedades hidráulicas do solo, especialmente a condutividade hidráulica e da densidade de comprimento radicular; na interface atmosfera de folhas, os fatores mais importantes são o déficit de pressão de vapor do ar atmosférico VPD. Estes fatores devem ser considerados de alguma forma na modelagem estresse hídrico em plantas. A detecção da ocorrência de estresse hídrico nas plantas no tratamento com déficit de irrigação foi feito por comparações entre o VPD e diferença de temperatura entre o dossel e o ar tdossel-ar e entre tdossel e a temperatura do bulbo úmido twb dos dois tratamentos hídricos. O início do estresse hídrico nas plantas com déficit de irrigação ocorreu em 05 de Agosto. As simulações com os modelos mecanísticos de extração da água do solo pelas raízes proposto por Jong van Lier et al. (2008) e de assimilação de CO2 proposto por Jacobs (1994) foram feitos com os dados de ambos os tratamentos. O modelo de extração foi sensível aos parâmetros hidráulicos do solo, especialmente a condutividade hidráulica e o comprimento radicular. A taxa de transpiração estimada pelo modelo de Jacobs (1994) mostrou-se dependente da temperatura do dossel utilizada para calcular o déficit de umidade específica folha-ar Ds e a condutância do mesofilo, do próprio Ds (dependente também da temperatura do ar), e do índice de área foliar. / Mechanistic parameterizations describe physically the interactions between crop and environment based on primary processes such as CO2 net assimilation and root water uptake from soil and how they are influenced by environmental conditions. An important purpose of developing mechanistic routines is to improve the understanding of a system by qualitative and quantitative integration of knowledge in a dynamic simulation model of a real system. Defining water stress as the condition in which stomatal resistance of plant leaves increases as a consequence of enhanced atmospheric demand and/or reduced soil water availability, the investigated hypothesis was that plant water stress is caused by environmental factors related to both the soilroot and leave-atmosphere interfaces. The main objective of the research was to identify which atmosphere and soil parameters are determinant and must be considered in crop water stress modeling. Soil and atmosphere water content were monitored under field conditions during the growing season of a Common Bean (Phaseolus vulgaris L.) crop between June and September, 2010, and correlated to plant water stress characterized by measurements of canopy temperature. The variables of interest, specifically the soil water pressure head, air temperature and humidity and canopy temperature were measured regularly at short intervals. Transpiration rate and stomatal conductance were measured occasionally. One plot was irrigated during the whole crop cycle (fully irrigated treatment), while the other one was subject to water stress in the reproductive phase (deficit irrigated treatment). The methodology used in this study supported the initial hypothesis. The main soil-root interface related factors that determine water stress are the soil hydraulic properties, especially the hydraulic conductivity, and the root length density; at the leaf atmosphere interface, the most important factor is the vapor pressure deficit of atmospheric air VPD. These factors must be somehow considered in crop water stress modeling. The detection of water stress occurrence in the deficit irrigated plants was made by comparisons between VPD and temperature difference between canopy and air tcanopy-air and between tcanopy and wet bulb temperature twb of the two irrigation treatments. The onset of water stress in deficit irrigated plants occurred on August 5. The simulations with the mechanistic models of soil water root uptake proposed by Jong van Lier et al. (2008) and of CO2 assimilation by Jacobs (1994) were made with data from the two treatments. The soil water uptake model was sensitive to soil hydraulic parameters, especially hydraulic conductivity and root length density. The transpiration rate estimated by the Jacobs (1994) model showed to be dependent on the canopy temperature used to calculate the specific humidity deficit between leaves and air Ds and the mesophyll conductance, on Ds (on its turn also dependent on air temperature), and on the leaf area index

A população e a demanda por água potável para abastecimento público na Região Metropolitana de São Paulo (RMSP) crescem continuamente, caracterizando uma situação limite na disponibilidade e uso desse bem. No período de 2000 a 2012, segundo dados do IBGE, a população na metrópole cresceu aproximadamente 11,87 por cento e, nesse mesmo período, a demanda por água tratada (m³/s) para abastecimento apresentou um aumento de 11,76 por cento. Esses dados evidenciam que a demanda por água é crescente, assim como a população. São necessárias novas alternativas de captação de água principalmente fora dos limites territoriais da RMSP, pois os mananciais da metrópole não possuem mais carga de água suficiente para abastecimento desse contingente populacional. Diante dessa tendência, é necessária uma integração na questão do desenvolvimento metropolitano principalmente no quesito de recursos hídricos para abastecimento público de água. Nesse sentido, o objetivo geral deste estudo foi investigar a dinâmica entre oferta e atendimento de demanda por água potável para abastecimento público na RMSP, associando às pressões sobre os ecossistemas que interferem na oferta do recurso água em quantidade e qualidade adequadas às necessidades da população. Os objetivos específicos buscaram rever os momentos críticos de escassez de água e a identificação de atores e ações tomadas para mitigação do problema, relacionar a atual condição ambiental e social dos principais mananciais abastecedores da RMSP e identificar uma possível correspondência entre a gestão dos recursos hídricos para abastecimento público de água e um modelo de gestão integrada. A metodologia utilizada baseou-se numa pesquisa de caráter exploratório na forma de estudo de caso e análise de conteúdo por meio da construção de categorias de análise, a partir de documentos e entrevistas aplicadas. Os dados e informações obtidos e discutidos em resultados e discussões demonstram que as decisões tomadas ao longo dos anos em relação à busca por água potável na RMSP ocorreram em momentos emergenciais de escassez do recurso. Porém, a tendência é sempre o aumento da demanda pela água por conta do contínuo crescimento populacional e da inclusão socioeconômica que vem ocorrendo na RMSP. Os mananciais metropolitanos estão demasiadamente poluídos, sendo necessária a captação de água em outras regiões, fora do limite da metrópole e gerando conflitos pelo uso da água. E as considerações finais evidenciam a importância de uma gestão integrada metropolitana para recursos hídricos envolvendo e integrando diferentes políticas setoriais ao gerenciamento dos recursos hídricos e aos planos de desenvolvimento urbano / The population and the potable water demand for public supply in the Metropolitan Region of São Paulo (RMSP) grow continuously, characterizing a limit on the availability and use of those goods. In the period from 2000 to 2012, according to IBGE data, the population in the metropolis grew approximately 11.87 per cent and during the same period, demand for treated water (m³ / s) for supply increased by 11.76 per cent. These data show that the demand for water is increasing as it is the population. New alternatives for water catchment are needed, primarily outside the territorial limits of the RMSP, because the watersheds of the metropolis have no more sufficient water load to supply this population group. Given this trend, an integration in the issue of metropolitan development is necessary, especially in the matter of water resources for public water supply. Accordingly, the aim of this study was to investigate the dynamics between supply and meeting demand for potable water for public supply in the RMSP associating the pressures on ecosystems that influence the supply of water resources in quantity and quality suited to the needs of the population. The specific objectives were to review the critical moments of water scarcity and the identification of actors and actions taken to mitigate the problem, relate to current social and environmental condition of the main water sources supplying the RMSP and identify a possible match between the management of water resources for public water supply and an integrated management model. The methodology applied was based on exploratory research in the form of case study and content analysis through the construction of analysis categories from documents and interviews applied. The data and information obtained and discussed in results and discussions show that the decisions taken over the years in relation to the search for clean water in the RMSP occurred in times of emergency by resource scarcity. But the trend is always the increasing demand for water due to the continuous population growth and economic inclusion that has occurred in the RMSP. The metropolitan watersheds are too polluted, requiring water uptake in other regions outside the boundary of the metropolis and generating conflicts over water use. The final considerations highlight the importance of an integrated metropolitan management for water resources, involving and integrating different sectoral policies to the management of water resources and urban development plans

Made available in DSpace on 2017-07-20T13:41:56Z (GMT). No. of bitstreams: 1 GABRIELA LEITE NEVES.pdf: 2850568 bytes, checksum: d212a8a17a32a986fc2b0200c7ee256e (MD5) Previous issue date: 2015-02-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Climate change is a matter of research, since there are still many questions about its causes and consequences. The effects of climate change are diverse, and can reach from the biodiversity of the planet to the economic, social and environmental sectors. Thus the knowledge of climate variables, their changes and impacts on natural resources is very important. Many researchers already had observed that water, a natural resource of great value, may be disturbed due to climate change. Thus the study of water availability related to climate change becomes necessary. The aim of this study was to analyze the impact of possible climate changes on water availability in the state of Paraná, Brazil. It were used daily data of precipitation, and maximum and minimum air temperature of 28 locations, with series of data from 1980 to 2009. By means of the PGECLIMA_R tool daily weather data were simulated for the period 2010 to 2099, using the climate scenarios projected in the IPCC AR4-, IPCC AR5- and trend analysis of historical data from 1980 to 2009. For the creation of the latter scenario, there was a parallel study to obtain the changes in temperature for each location, which were then projected in the simulations. In order to quantify the water availability under the proposed conditions, we estimated the water balance for the current and simulated weather data using the methodology of Thornthwaite and Matter (1955). With interpolation tools, the results of changes in temperature and hydric indices obtained by the water balance were mapped for the entire state of Paraná. The hydric indices were then compared in different scenarios and analyzed periods. The results show that the state of Paraná has a great climate variability across regions. The trend analysis of air temperature pointed from reductions to increases in this variable and these were responsible for different impacts on water availability. In general, all scenarios were responsible for reductions in water availability, but the northern region is more susceptible to these reductions. The trend scenario showed reductions in water availability for most regions, but there was also increase in some specific regions of Parana State. / As modificações do clima é assunto de pesquisa, já que ainda existem muitos questionamentos sobre suas causas e consequências. Os efeitos das mudanças climáticas são diversos, e podem atingir desde a biodiversidade do planeta até os setores econômicos, sociais e ambientais. Sendo assim o conhecimento das variáveis climáticas, de suas alterações e seus impactos nos recursos naturais é de suma importância. Muitos pesquisadores já observaram que a água, um recurso natural de grande valor, poderá sofrer perturbações decorrentes das mudanças climáticas. Assim o estudo da disponibilidade hídrica frente às mudanças climáticas se torna necessário. O objetivo desse trabalho foi analisar o impacto de possíveis mudanças climáticas na disponibilidade hídrica no estado do Paraná. Utilizou-se dados diários de precipitação, temperatura máxima e temperatura mínima de 28 localidades, que correspondem a uma série de dados de 1980 a 2009. Por meio da ferramenta PGECLIMA_R, realizaram-se simulações de dados climáticos diários, para o período de 2010 até 2099, considerando os cenários climáticos projetados no IPCC-AR4, IPCC-AR5 e na análise de tendência dos dados históricos no período de 1980 a 2009. Para a criação deste último cenário, realizou-se um estudo paralelo em que se obteve as alterações na temperatura para cada localidade, as quais foram então projetadas nas simulações. A fim de quantificar a disponibilidade hídrica nas condições propostas, estimou-se os balanço hídricos para os dados climáticos atuais e para os simulados, pela metodologia de Thornthwaite e Matter (1955). Com ferramentas de interpolação, os valores das alterações na temperatura e dos índices hídricos obtidos pelo balanço hídrico foram espacializados para todo o estado do Paraná. Os índices hídricos então foram comparados nos diferentes cenários e períodos analisados. Os resultados apontam que o estado do Paraná apresenta uma grande variabilidade climática entre suas regiões. A análise de tendência da temperatura do ar apontou desde reduções a aumentos nessa variável e essas alterações foram responsáveis também por diferentes impactos na disponibilidade hídrica. De forma geral, todos os cenários foram responsáveis por reduções na disponibilidade hídrica, porém a região norte foi aquela que mostrou ser mais suscetível a essas reduções. O cenário de tendência apontou reduções na disponibilidade hídrica para a maioria das regiões, porém houve aumento pontual da mesma em algumas regiões especificas do Estado do Paraná.

Orientador: Fernando Braz Tangerino Hernandez / Resumo: Os estudos relacionados aos recursos hídricos têm se mostrado cada vez mais necessários para os Órgãos Gestores de Recursos Hídricos devido à freqüente possibilidade de escassez de água para os usos múltiplos nas bacias hidrográficas. A Unidade de Gestão de Recursos Hídricos - UGRHI 18 pode sofrer conflitos pelo uso de água em função de suas demandas, além de apresentar a maior evapotranspiração do Estado de São Paulo e oito meses de deficiência hídrica no ano. Diante desta condição climática, o uso da irrigação é fundamental para repor as necessidades hídricas e garantir a produtividade máxima das culturas. O objetivo geral deste estudo foi avaliar o potencial de expansão da irrigação na Bacia Hidrográfica do Rio São José dos Dourados. Os objetivos específicos foram: Fazer o balanço entre disponibilidade e demanda em cada Sub-bacia; e por fim, identificar áreas potenciais para irrigação. Neste trabalho foram identificadas na Bacia Hidrográfica do Rio São José dos Dourados as Áreas potenciais de irrigação, que são aquelas naturalmente aptas à agricultura irrigada, sem restrições ambientais, além de disponibilidade de água, e as Áreas não potenciais de irrigação que são as demais áreas onde um conjunto de fatores naturais e ambientais, impede o desenvolvimento da agricultura irrigada nos padrões atuais. Este estudo demonstrou que o potencial de expansão das áreas irrigadas da UGRHI 18, se referindo a Bacia como um todo chega a 1270 %, ou seja, quase 13 vezes mais que a área at... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Studies related to water resources have been increasingly needed by Water Resources Governing Bodies because of the frequent possibility of water scarcity for multiple uses in river basins. The Water Resources Management Unit - UGRHI 18 can suffer conflicts due to the use of water as a function of its demands, in addition to presenting the highest evapotranspiration in the State of São Paulo and eight months of water deficiency in the year. In view of this climatic condition, the use of irrigation is fundamental to restore water requirements and guarantee the maximum productivity of crops. The general objective of this study was to evaluate the potential of irrigation expansion in the São José dos Dourados River Basin. The specific objectives were: to balance the availability and demand in each Sub-basin; and finally identify potential areas for irrigation. In this work, the Potential Irrigation Areas were identified in the San José dos Dourados River Basin, which are those that are naturally suitable for irrigated agriculture, with no environmental restrictions, besides the availability of water, and the non-potential irrigation areas that are the other areas where a set of natural and environmental factors, prevents the development of irrigated agriculture in current patterns. This study demonstrated that the potential for expansion of the irrigated areas of UGRHI 18, referring to the Basin as a whole reaches 1270%, that is, almost 13 times more than the current irrigated a... (Complete abstract click electronic access below) / Mestre

Parametrizações mecanísticas descrevem fisicamente a interação das plantas com o ambiente baseando-se em processos fundamentais, como assimilação de líquida de CO2 e extração da água do solo pelas raízes, influenciados pelas condições do ambiente. O objetivo principal dessas rotinas é aumentar o entendimento do sistema estudado pela integração quantitativa e qualitativa do conhecimento em um modelo de simulação dinâmica do sistema real. Definindo estresse hídrico como a condição em que uma planta aumenta a resistência estomática em conseqüência do aumento da demanda atmosférica e/ou da redução da disponibilidade hídrica no solo, tem-se como hipótese que o déficit hídrico em plantas é causado por fatores ambientais relacionados com as interfaces solo-raiz e folha-atmosfera. O objetivo geral desse estudo é identificar quais são as variáveis do solo e da atmosfera determinantes e que devem ser consideradas na modelagem da deficiência hídrica em plantas. Os teores de água no solo e na atmosfera foram monitorados em condições de campo durante o desenvolvimento da cultura de feijão (Phaseolus vulgaris L.) entre Junho e Setembro de 2010, e correlacionados ao estresse hídrico caracterizado por medições de temperatura do dossel. As variáveis de interesse, especificamente o potencial matricial da água do solo, a temperatura e a umidade do ar e a temperatura do dossel foram medidas regularmente em intervalos de 30 minutos. A taxa de transpiração e a condutância estomática foram medidas ocasionalmente. Uma parcela foi irrigada durante todo o ciclo da cultura (tratamento totalmente irrigada), enquanto a outra foi submetida ao estresse hídrico na fase reprodutiva (tratamento com déficit de irrigação). A metodologia utilizada neste estudo deu suporte à hipótese inicial. Os principais fatores relacionados à interface solo-raiz são as propriedades hidráulicas do solo, especialmente a condutividade hidráulica e da densidade de comprimento radicular; na interface atmosfera de folhas, os fatores mais importantes são o déficit de pressão de vapor do ar atmosférico VPD. Estes fatores devem ser considerados de alguma forma na modelagem estresse hídrico em plantas. A detecção da ocorrência de estresse hídrico nas plantas no tratamento com déficit de irrigação foi feito por comparações entre o VPD e diferença de temperatura entre o dossel e o ar tdossel-ar e entre tdossel e a temperatura do bulbo úmido twb dos dois tratamentos hídricos. O início do estresse hídrico nas plantas com déficit de irrigação ocorreu em 05 de Agosto. As simulações com os modelos mecanísticos de extração da água do solo pelas raízes proposto por Jong van Lier et al. (2008) e de assimilação de CO2 proposto por Jacobs (1994) foram feitos com os dados de ambos os tratamentos. O modelo de extração foi sensível aos parâmetros hidráulicos do solo, especialmente a condutividade hidráulica e o comprimento radicular. A taxa de transpiração estimada pelo modelo de Jacobs (1994) mostrou-se dependente da temperatura do dossel utilizada para calcular o déficit de umidade específica folha-ar Ds e a condutância do mesofilo, do próprio Ds (dependente também da temperatura do ar), e do índice de área foliar. / Mechanistic parameterizations describe physically the interactions between crop and environment based on primary processes such as CO2 net assimilation and root water uptake from soil and how they are influenced by environmental conditions. An important purpose of developing mechanistic routines is to improve the understanding of a system by qualitative and quantitative integration of knowledge in a dynamic simulation model of a real system. Defining water stress as the condition in which stomatal resistance of plant leaves increases as a consequence of enhanced atmospheric demand and/or reduced soil water availability, the investigated hypothesis was that plant water stress is caused by environmental factors related to both the soilroot and leave-atmosphere interfaces. The main objective of the research was to identify which atmosphere and soil parameters are determinant and must be considered in crop water stress modeling. Soil and atmosphere water content were monitored under field conditions during the growing season of a Common Bean (Phaseolus vulgaris L.) crop between June and September, 2010, and correlated to plant water stress characterized by measurements of canopy temperature. The variables of interest, specifically the soil water pressure head, air temperature and humidity and canopy temperature were measured regularly at short intervals. Transpiration rate and stomatal conductance were measured occasionally. One plot was irrigated during the whole crop cycle (fully irrigated treatment), while the other one was subject to water stress in the reproductive phase (deficit irrigated treatment). The methodology used in this study supported the initial hypothesis. The main soil-root interface related factors that determine water stress are the soil hydraulic properties, especially the hydraulic conductivity, and the root length density; at the leaf atmosphere interface, the most important factor is the vapor pressure deficit of atmospheric air VPD. These factors must be somehow considered in crop water stress modeling. The detection of water stress occurrence in the deficit irrigated plants was made by comparisons between VPD and temperature difference between canopy and air tcanopy-air and between tcanopy and wet bulb temperature twb of the two irrigation treatments. The onset of water stress in deficit irrigated plants occurred on August 5. The simulations with the mechanistic models of soil water root uptake proposed by Jong van Lier et al. (2008) and of CO2 assimilation by Jacobs (1994) were made with data from the two treatments. The soil water uptake model was sensitive to soil hydraulic parameters, especially hydraulic conductivity and root length density. The transpiration rate estimated by the Jacobs (1994) model showed to be dependent on the canopy temperature used to calculate the specific humidity deficit between leaves and air Ds and the mesophyll conductance, on Ds (on its turn also dependent on air temperature), and on the leaf area index

A população e a demanda por água potável para abastecimento público na Região Metropolitana de São Paulo (RMSP) crescem continuamente, caracterizando uma situação limite na disponibilidade e uso desse bem. No período de 2000 a 2012, segundo dados do IBGE, a população na metrópole cresceu aproximadamente 11,87 por cento e, nesse mesmo período, a demanda por água tratada (m³/s) para abastecimento apresentou um aumento de 11,76 por cento. Esses dados evidenciam que a demanda por água é crescente, assim como a população. São necessárias novas alternativas de captação de água principalmente fora dos limites territoriais da RMSP, pois os mananciais da metrópole não possuem mais carga de água suficiente para abastecimento desse contingente populacional. Diante dessa tendência, é necessária uma integração na questão do desenvolvimento metropolitano principalmente no quesito de recursos hídricos para abastecimento público de água. Nesse sentido, o objetivo geral deste estudo foi investigar a dinâmica entre oferta e atendimento de demanda por água potável para abastecimento público na RMSP, associando às pressões sobre os ecossistemas que interferem na oferta do recurso água em quantidade e qualidade adequadas às necessidades da população. Os objetivos específicos buscaram rever os momentos críticos de escassez de água e a identificação de atores e ações tomadas para mitigação do problema, relacionar a atual condição ambiental e social dos principais mananciais abastecedores da RMSP e identificar uma possível correspondência entre a gestão dos recursos hídricos para abastecimento público de água e um modelo de gestão integrada. A metodologia utilizada baseou-se numa pesquisa de caráter exploratório na forma de estudo de caso e análise de conteúdo por meio da construção de categorias de análise, a partir de documentos e entrevistas aplicadas. Os dados e informações obtidos e discutidos em resultados e discussões demonstram que as decisões tomadas ao longo dos anos em relação à busca por água potável na RMSP ocorreram em momentos emergenciais de escassez do recurso. Porém, a tendência é sempre o aumento da demanda pela água por conta do contínuo crescimento populacional e da inclusão socioeconômica que vem ocorrendo na RMSP. Os mananciais metropolitanos estão demasiadamente poluídos, sendo necessária a captação de água em outras regiões, fora do limite da metrópole e gerando conflitos pelo uso da água. E as considerações finais evidenciam a importância de uma gestão integrada metropolitana para recursos hídricos envolvendo e integrando diferentes políticas setoriais ao gerenciamento dos recursos hídricos e aos planos de desenvolvimento urbano / The population and the potable water demand for public supply in the Metropolitan Region of São Paulo (RMSP) grow continuously, characterizing a limit on the availability and use of those goods. In the period from 2000 to 2012, according to IBGE data, the population in the metropolis grew approximately 11.87 per cent and during the same period, demand for treated water (m³ / s) for supply increased by 11.76 per cent. These data show that the demand for water is increasing as it is the population. New alternatives for water catchment are needed, primarily outside the territorial limits of the RMSP, because the watersheds of the metropolis have no more sufficient water load to supply this population group. Given this trend, an integration in the issue of metropolitan development is necessary, especially in the matter of water resources for public water supply. Accordingly, the aim of this study was to investigate the dynamics between supply and meeting demand for potable water for public supply in the RMSP associating the pressures on ecosystems that influence the supply of water resources in quantity and quality suited to the needs of the population. The specific objectives were to review the critical moments of water scarcity and the identification of actors and actions taken to mitigate the problem, relate to current social and environmental condition of the main water sources supplying the RMSP and identify a possible match between the management of water resources for public water supply and an integrated management model. The methodology applied was based on exploratory research in the form of case study and content analysis through the construction of analysis categories from documents and interviews applied. The data and information obtained and discussed in results and discussions show that the decisions taken over the years in relation to the search for clean water in the RMSP occurred in times of emergency by resource scarcity. But the trend is always the increasing demand for water due to the continuous population growth and economic inclusion that has occurred in the RMSP. The metropolitan watersheds are too polluted, requiring water uptake in other regions outside the boundary of the metropolis and generating conflicts over water use. The final considerations highlight the importance of an integrated metropolitan management for water resources, involving and integrating different sectoral policies to the management of water resources and urban development plans

A feasibility study of an irrigation development proposal should include an analysis of the effects of water supply conditions on the degree to which development objectives are expected to be realised. A method of making this analysis was developed based on procedures for solving two problems. These were; (a) optimally allocating a property's available supply of water among competing crops, and, (b) optimally controlling an open channel distribution system to meet temporally and spatially varying water demand. The procedure developed for solving (a) was applied. A stochastic dynamic programming procedure was developed to optimally schedule the irrigation of a single crop, subject to constraints on the timing of water availability and total application depth. A second procedure was developed, employing a constrained differential dynamic programming algorithm, for determining optimal irrigation schedules for use with variable application depth systems, and when several crops compete for an intra-seasonally limited supply of water. This procedure was called, as frequently as water supply conditions allowed, to provide short-term irrigation schedules in a computer simulation of the optimal irrigation of several crops. An application system model was included in these procedures to transform a crop water-use production function into the required irrigation water-use production function. This transformation was a function of the application device type and the mean application depth. From an analysis of the on-property effects of water supply conditions, it was concluded that in order to achieve high economic and irrigation efficiencies, water supply conditions must be sufficiently flexible to allow the application system operator to vary the mean application depth but not necessarily the time periods of water availability. Additionally, irrigation scheduling procedures which seek economically optimum strategies offer the potential to achieve a maximum level of net benefit at levels of water availability significantly lower than has previously been used for design purposes.

The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.