Orientador: Luiz Fernando Rolim de Almeida / Resumo: As plantas estão expostas à seca extrema e cada vez mais frequente devido aos cenários das mudanças climáticas. A superação dos períodos de estresse hídrico e a rápida recuperação com o retorno da estação chuvosa são características de ajuste importantes para o estabelecimento e distribuição dos vegetais. Para amenizar os danos causados pela seca e intensa radiação, o metabolismo vegetal dispõe de mecanismos bioquímicos, anatômicos e epigenéticos que auxiliam na eliminação de radicais livres, no transporte e reserva de água e garantem respostas mais rápidas à reidratação assim que a água estiver novamente disponível no ambiente. Neste contexto, estudos baseados na deficiência hídrica se limitam em expor plantas a apenas um ciclo de défice, o que não acontece normalmente no ambiente. Os vegetais armazenam informações de estresses precedentes que não se resumem a padrões de sinalização isolados, mas funcionam como marcas deixadas anteriormente que auxiliam nas respostas a adversidades futuras. Deste modo, as consequências da seca de forma recorrente relacionando o estresse e a reidratação pós-estresse ainda não são bem compreendidos. A espécie utilizada para este estudo foi a Copaifera langsdorffii Desf. que possui folhas com mecanismos anatômicos e fisiológicos para superação das alterações ambientais. É conhecida pelas propriedades medicinais por meio do óleo amplamente consumido pela população em geral. Copaifera langsdorffii que ocorre em ambientes de diferentes regimes híd... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Plants are exposed to extreme drought increasingly frequent due to climate change scenarios. Overcoming periods of water stress and fast recovery with the rainy season return are characteristics of important adjustment for the establishment and wide vegetables distribution. To mitigate the damages caused by drought and intense radiation, plant metabolism features biochemical, anatomical and epigenetic mechanisms that assist in scavenging free radicals, increase the transport and water supply and ensure faster response to rehydration as soon as water is available in the environment again. In this context, studies based on water deficiency are limited to exposing plants only in one deficit cycle, which does not normally happen in the environment. Vegetables store information from previous stresses that are not limited to isolated signaling patterns, but function as previously left imprint that assist in responses to future adversities. Thus, the consequences of recurrent drought form related to stress and post-stress rehydration are not well understood yet. The species used for this study was Copaifera langsdorffii Desf. which has leaves with anatomical and physiological mechanisms to overcome environmental changes. The species has medicinal properties through the oil widely consumed by Brazilian population. It is present in several vegetation types in Brazil and South America that have different water and light pattern. These factors, among others, make this one of the most im... (Complete abstract click electronic access below) / Doutor

Bread wheat (Triticum aestivum L.) is one of the most important cereal crops grown in the world. It has great importance because it constitutes a major source of carbohydrate for more than one third of the world’s population (Budak et al., 2013). In the last three decades, drought conditions are becoming more widespread in wheat production areas including Europe, Australia and Asia, and it is considered a major cause of reduced wheat growth and productivity in most developing countries with semi-arid climates. Drought constitutes the most important threat for wheat production in Iraq and especially for the Kurdistan Regional Governate owing to the limited source of water during at least some part of the growing period. Because wheat is considered a staple food and has economic importance for the Kurdistan Regional Government research is needed to determine the production capacity of Iraqi wheat varieties under drought stress and the potential for the maximization of the drought tolerance response. The soil moisture holding capacity of the intended growing medium was measured gravimetrically in pots with and without wheat plants and correlated with the soil capacitance measured using a TDR Theta Probe (Delta-T Devices). This was used to determine the available water content of the soil (AWC) and to control and manage the watering regimes during drought studies. The results of a study of the response of different cultivars of Iraqi wheat (Triticum aestivum L.) to watering regimes of 70% and 50% showed that drought stress had a significant effect on the biomass and yield traits especially tiller number and stem bundle weight compared to normal conditions. The highest significant difference was observed for cv. Tamooz 2 in comparison to Adana 99, but there was a little difference between cvs. Rizgary and Sham 6. The effect of the exogenous application of salicylic acid (SA) and molybdenum (Mo) on drought tolerance of cvs. Tamooz 2 and Adana 99, showed that Tamooz 2 had higher values for growth characteristics and higher yield potential when sprayed with a lower concentration of SA (1.44 mM) under well-watered conditions in comparison with Adana 99. The effect of spraying variety Tamooz 2 with SA at different growth stages indicated that biomass production and yield components (the number of spikes/pot, grain dry weight and average 1000 grain dry weight) significantly increased at both stem+flower as well as leaf+stem+flower sprayings for plants subjected to drought. Also, SA treatments at stem extension and flowering had a positive effect on the up-regulation of the drought response gene CBF/DREB under drought stress conditions. These findings indicate that agronomic treatments with exogenous applications of salicylic acid and molybdenum could help to reduce the effects of drought in the field.

abstract: This study investigates the vulnerability of subsistence agriculturalists to food shortfalls associated with dry periods. I approach this effort by evaluating prominent and often implicit conceptual models of vulnerability to dry periods used by archaeologists and other scholars investigating past human adaptations in dry climates. The conceptual models I evaluate rely on an assumption of regional-scale resource marginality and emphasize the contribution of demographic conditions (settlement population levels and watershed population density) and environmental conditions (settlement proximity to perennial rivers and annual precipitation levels) to vulnerability to dry periods. I evaluate the models and the spatial scales they might apply by identifying the extent to which these conditions influenced the relationship between dry-period severity and residential abandonment in central Arizona from A.D. 1200 to 1450. I use this long-term relationship as an indicator of potential vulnerability to dry periods. I use tree-ring precipitation and streamflow reconstructions to identify dry periods. Critically examining the relationship between precipitation conditions and residential abandonment potentially sparked by the risk of food shortfalls due to demographic and environmental conditions is a necessary step toward advancing understanding of the influences of changing climate conditions on human behavior. Results of this study support conceptual models that emphasize the contribution of high watershed population density and watershed-scale population-resource imbalances to relatively high vulnerability to dry periods. Models that emphasize the contribution of: (1) settlement population levels, (2) settlement locations distant from perennial rivers, (3) settlement locations in areas of low average annual precipitation; and (4) settlement-scale population-resource imbalances to relatively high vulnerability to dry periods are, however, not supported. Results also suggest that people living in watersheds with the greatest access to and availability of water were the most vulnerable to dry periods, or at least most likely to move when confronted with dry conditions. Thus, commonly held assumptions of differences in vulnerability due to settlement population levels and inherently water poor conditions are not supported. The assumption of regional-scale resource marginality and widespread vulnerability to dry periods in this region of the U.S. Southwest is also not consistently supported throughout the study area. / Dissertation/Thesis / Ph.D. Anthropology 2010

A seca que assola o norte de Minas Gerais é um desencadeante de severos impactos socioambientais. Mudanças na distribuição das precipitações, ou mesmo a redução no volume de chuvas é fator suficiente para a desorganização da atividade econômica regional. Neste contexto, este trabalho analisou a distribuição espaço-temporal da seca/estiagem no norte de Minas Gerais, entre 2003 a 2014. A metodologia consistiu na elaboração de série temporal de anomalia padronizada de NDWI utilizando imagens de reflectância MOD13Q1/MODIS. Para a realização das análises utilizou-se como base: os decretos de anormalidade por motivo de seca/estiagem, dados de perdas e danos, de precipitação e de variação de água da subsuperfície das soluções GRACE. Foram realizadas correlações entre NDWI e precipitação e entre anomalia padronizada de NDWI e anomalia de precipitação, considerando dados sem e com 30 dias de defasagem. Foi aplicado teste de médias, teste t de Student, para a anomalia padronizada de NDWI e a anomalia de precipitação, em um intervalo de confiança de 95%. Os resultados demonstraram que a anomalia padronizada de NDWI identificou de forma satisfatória três períodos de seca/estiagem na região. Estes corroboram com os dados de decretos de emergência e calamidade pública, sendo observado um maior número de decretos, principalmente, nestes períodos. Dois períodos identificados como de seca/estiagem foram noticiados como de estiagem severa no norte de Minas Gerais. Esse fato corrobora os dados de anomalia padronizada de NDWI com a situação ocorrida na região. O quantitativo de áreas afetadas por seca também evidencia o mesmo período de maiores números de ocorrências de seca/estiagem e deficiência na distribuição da precipitação. No entanto, o emprego de anomalia padronizada de NDWI na identificação seca/estiagem, por si só, pode não ser suficiente para essa identificação, uma vez que, o fenômeno pode ocorrer e causar danos e prejuízos, em meio a uma paisagem verde, como constatado para 2010. As análises estatísticas mostraram que existem correlações com graus de intensidade melhores entre o NDWI e a precipitação com uma defasagem de 30 dias. Fato também observado para os dados de anomalia padronizada de NDWI e anomalia de precipitação, todavia, foram observadas correlações de fraca a moderada. O teste de médias apresentou diferenças entre as médias apenas para o ano de 2014. Apesar de em todos os outros períodos as médias não serem estatisticamente diferentes entre si, foram verificados baixos valores de p-value, com excessão do período entre 2008 e 2011, onde são verificados p-value entre 0,4 a 0,9. Ainda que os testes estatísticos não apresentaram uma ótima significância, a variação temporal dos dados de anomalia padronizada de NDWI e de anomalia de precipitação evidencia uma relação similar entre esses dados. Por fim, a comparação com dados das soluções GRACE, identificou os mesmos períodos verificados com a anomalia padronizada de NDWI, sendo então, observado que estes dados corroboram entre si na identificação de seca/estiagem no norte de Minas Gerais. / The drought that affects the north of Minas Gerais State causes severe socio-environment impacts. Changes on the precipitation distribution or even the reduction of the raining amount is enough reason for regional disorganization. In this context, this work analyzed the drought spatial-temporal distribution in the north of Minas Gerais State, between 2003 and 2014. The methodology consisted on the elaboration of time series of standardized anomaly NDWI using images of reflectance MOD13Q1/MODIS. For the analysis it was used the following basis: the abnormality decrees caused by drought, damage and losses data, precipitation and the water subsurface range on GRACE solution. Correlations were conducted between NDWI and precipitation, as well as between standardized anomaly NDWI and precipitation anomaly, considering data with and without 30 days of gap. It was applied average test, the Student t-test, for the standardized anomaly NDWI and precipitation anomaly, with a confidence range of 95%. Results demonstrated that standardized anomaly NDWI satisfactorily identified three seasons of drought in this region. It corroborates with emergency decrees and public calamity data, in what it was observed a higher number of decrees, especially in these periods. Two seasons identified as drought were reported as severe drought in the north of Minas Gerais State. This fact validates the standardized anomaly NDWI data with the situation occurred in the region. The quantity of affected areas drought, also evidences the same period of larger numbers of occurrences drought and disability in the distribution of precipitation. However, the use of standardized anomaly NDWI by itself on the identification of drought may not be enough evidence for this association, since the phenomenon can occur and cause damages and losses among a green landscape, as seen in 2010. Statistical analysis demonstrated that there are correlations with better intensity degrees between the NDWI and the precipitation with a gap of 30 days. This fact was also observed for the standardized anomaly NDWI and precipitation anomaly data, however, mild to moderate correlations were observed. Student t-test demonstrated differences between the averages only for the year of 2014. Despite for all other periods averages were not statistically different, they were observed p-value low values, with the exception of the period between 2008 and 2011, which are verified p-value between 0.4 and 0.9. Although statistical tests did not demonstrated a great significance, the temporal variation of standardized anomaly NDWI data and precipitation anomaly evidenciate a similar relationship between these data. Lastly, the comparison with data from GRACE solutions, identified the same periods verified with the standardized anomaly NDWI, being then observed that these data corroborates between them in the identification of draught in the north of Minas Gerais State.

Os processos de arenização no sudoeste do Rio Grande do Sul têm sua explicação na relação entre a fragilidade do meio e a dinâmica hídrica, esta sustentada por eventos torrenciais de chuva. A presença de processos erosivos sob a forma de ravinamentos e de voçorocamentos e a exposição das formações superficiais nos areais atestam, nessa área, elevada mobilidade de sedimentos. Além disso, atividades agropecuárias sem o manejo adequado têm intensificado esses processos naturais, ampliando a interação hidrossedimentar entre as vertentes e os fundos de vale. Embora haja inúmeros trabalhos que abordam o processo de arenização e as dinâmicas do espaço geográfico no sudoeste do Rio Grande do Sul, há ainda uma lacuna em pesquisas que visam compreender suas inter-relações com a morfodinâmica fluvial. Tendo como recorte espacial a Bacia Hidrográfica do Arroio Miracatu (BHAM), esta pesquisa visa analisar, justamente, a importância de eventos hidrológicos extremos na morfodinâmica fluvial e a sua interação com os processos de arenização. Dados de chuva e vazão da BHAM foram analisados com vistas a identificar o regime pluvio-fluviométrico. Para tanto foram empregados parâmetros estatísticos com a finalidade de discriminar os eventos mais comuns daqueles mais raros. Como a ênfase do trabalho são os eventos hidrológicos extremos, estes foram observados a partir de diferentes escalas temporais (anual, mensal, pentadal e diário) e relacionados tanto ao excesso, como à escassez hídrica. Os resultados apontam para uma elevada variabilidade nas chuvas, que tendem a se concentrar em um número reduzido de dias, tanto anualmente, como mensalmente. Uma relação muito próxima entre a chuva e a vazão foi observada, de tal modo que os anos-padrão de chuva apresentaram correspondência com aqueles classificados pela Condição Hídrica da Bacia Hidrográfica (CHid). Isso decorre do fato de que tanto o El Niño Oscilação Sul (ENOS) como a Oscilação Decadal do Pacífico (ODP) modulam as chuvas e, consequentemente, as vazões na BHAM. Adicionalmente, foram identificados períodos ora mais secos (ODP-), ora mais chuvosos (ODP+). Esses períodos foram fundamentais para a compreensão da morfodinâmica fluvial, que é moldada por uma sucessão de regimes dominados por estiagem ou por inundação. Com a finalidade de avaliar esses processos de ajustamento foi selecionado um segmento localizado no médio curso da sanga da Areia. Nesse local a rede de drenagem é influenciada pelos processos de arenização, havendo conexão entre as vertentes e o fundo de vale, com intenso aporte de sedimentos. Com base em imagens de sensoriamento remoto (fotos aéreas e satélite) foi possível identificar a posição do canal em dez ocasiões diferentes, no período que se insere entre 1948-2013. Os ajustamentos que se processaram nesse segmento permitiram dividi-lo em dois trechos distintos (a montante e a jusante), com evolução diferenciada. Além dos ajustamentos na morfologia de canal, foram observados ainda variações na largura do canal, demonstrando ora um padrão entrelaçado (mais largo), ora meandrante (mais estreito). Concomitantemente a esses ajustamentos, a incisão fluvial promoveu a esculturação de diferentes feições, sendo possível delimitar dois níveis de terraços e um nível de planície de inundação. Na intenção de compreender os processos erosivo-deposicionais, procedeu-se ao monitoramento de nove seções transversais no trecho a montante do segmento estudado na sanga da Areia. O canal fluvial, inicialmente meandrante com calha estreita e profunda, passou para um padrão entrelaçado, com leito muito mais largo e raso ao fim do levantamento. Esses ajustamentos não se processaram de modo contínuo, mas bruscamente, em decorrência de pulso excepcional de cheia por ocasião de chuva pentadal extrema. Esse pulso promoveu um aumento brusco da carga sedimentar esculturando um canal entrelaçado (raso e largo) pela estocagem intracanal do material. Ajustamentos dessa natureza moldam a morfologia do canal e sugerem ocorrer de modo periódico na sanga da Areia. / The sandization processes in the southwestern of Rio Grande do Sul State have their explanation on the relationship between environment fragility and water dynamics, and this, supported by torrential rain event. The presence of erosive processes in the form of ravines and gullies and the exposure of soil surface in the sand deposits attest, in this area, high sediment mobility. In addition, agricultural activities without appropriate management have intensified these natural processes, expanding water-sediment interaction between the slopes and valley bottoms. Although there are numerous studies that discuss the sandization process and the dynamics of the geographic space in the southwestern of Rio Grande do Sul, there is still, a gap in research aimed at understanding their interrelations with the fluvial morphodynamics. The Miracatu arroyo watershed was defined as the study area of this research, which aims to analyze the importance of extreme hydrological events in the river morphodynamics and their interaction with sandization processes. Rainfall and river-flow were analyzed in order to identify the rain-flow regime. For this purpose, statistical parameters were used in order to discriminate the most common of those rare events. The extreme hydrological events were observed from different time scales (annual, monthly, daily and pentad) and related either to excess, as the water scarcity. The results indicate a high variability in rainfall that tend to occur in a few days both annual as monthly. Was observed a relationship between rainfall and river-flow and it happens due the influence of El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) that modulate the rains and therefore the flow in Miracatu Arroyo. Furthermore, was identified a succession of drier (PDO-) and rainiest periods (PDO+). These periods were fundamental to the understanding of fluvial morphodynamics, once it allow characterize alternating drought- and flood dominated regimes. In order, to evaluate the fluvial adjustment processes were selected a segment-river located in the Areia Creek. In this place, the drainage network is influenced by sandization processes, with connection between the slopes and the valley bottom, with strong input of sediments. Based on remote sensing images (air photo and satellite) was identified the channel position in ten occasions in the period of 1948-2013. The fluvial adjustments that were processed in this segment allowed to divide it into two distinct reaches (upstream and downstream reaches), with different evolution. It was also observed variations in the width and channel pattern, sometimes showing a braided channel (wider) while in others a meandering course (narrower). Concurrently with these adjustments, the fluvial incision promoted the sculpturing of different features and it is possible define two levels of terraces and a flood plain level. The intention to understand the erosive-depositional processes proceeded to monitoring nine cross sections in the upstream reach of the segment-river studied in Areia Creek. The river channel, initially meandering with narrow and deep channel, passed for a braided pattern with bed wider and shallower at the end of the survey. These fluvial adjustments are not processed in a continuous manner, but abruptly, due to exceptional flood-pulse during extreme pentadal rain. This event promoted an abrupt increase in load-bed forming a braided channel (shallow and wide) by in-channel sediment storage. Adjustments of this nature shape the channel morphology and occur periodically in Areia Creek.

Understanding the relationship between drought and population dynamics is increasingly important, particularly in areas where high population growth corresponds with increasing drought risk due to climate change. We examine the relationship between drought events and population dynamics using a stylized hydrology-demography model that has been calibrated to simulate plausible feedbacks for the population decline of the Ancient Maya of Central America. We employ a deterministic and a stochastic approach. We find that the impact of drought increases abruptly once a critical threshold of population density is exceeded. The critical threshold depends on the intensity and duration of the drought as well as on the level of technology adopted by society, the extent of markets and societal behavior. The simulations show that, for a society to be as food secure post-climate change as they are pre-climate change, strategies would have to be adopted to not only increase the region's capacity to provide sufficient resources for its growing population, but also to buffer the impact of a drier climate on productivity. This study provides suggestions on how technological, societal and economic development can modify the system to mitigate the impacts of climate change on the human population.

The primary objectives of this study are to understand if and how cities are adapting to heat and water stress and to characterize their understanding of the potential tradeoffs associated with vegetation-based strategies. I address these objectives using two approaches: a comparative analysis of climate adaptation and sustainability planning documents in cities vulnerable to heat and water stress and an in-depth case study of the response to heat and water threats in Los Angeles. The comparative analysis of city plans builds a broad understanding of how cities are planning to adapt to heat and water stress and the degree to which they articulate an understanding of, and mitigate the potential for, maladaptive measures. The Los Angeles case study provides the opportunity to more deeply trace how the process of adapting to heat and water stress has unfolded in a single city. To do so, I locate the city’s contemporary policies in an historical continuum with previous municipal environmental policy efforts, in local patterns of urban development and their entailing political and economic foundations, and in regional, state, national, and international environmental policy hierarchies.

abstract: With the ongoing drought surpassing a decade in Arizona, scholars, water managers and decision-makers have heightened attention to the availability of water resources, especially in rapidly growing regions where demand may outgrow supplies or outpace the capacity of the community water systems. Community water system managing entities and the biophysical and social characteristics of a place mediate communities' vulnerability to hazards such as drought and long-term climate change. The arid southwestern Phoenix metropolitan area is illustrative of the challenges that developed urban areas in arid climates face globally as population growth and climate change stress already fragile human-environmental systems. This thesis reveals the factors abating and exacerbating differential community water system vulnerability to water scarcity in communities simultaneously facing drought and rapid peri-urban growth. Employing a grounded, qualitative comparative case study approach, this thesis explores the interaction of social, biophysical and institutional factors as they effect the exposure, sensitivity and adaptive capacity of community water systems in Cave Creek and Buckeye, Arizona. Buckeye, once a small agricultural town in the West Valley, is wholly dependent on groundwater and currently planning for massive development to accommodate 218,591 new residents by 2020. Amid desert hills and near Tonto National Forest in the North Valley, Cave Creek is an upscale residential community suffering frequent water outages due to aging infrastructure and lack of system redundancy. Analyzing interviews, media accounts and policy documents, a narrative was composed explaining how place based factors, nested within a regional institutional water management framework, impact short and long-term vulnerability. This research adds to the library of vulnerability assessments completed using Polsky et al.'s Vulnerability Scoping Diagram and serves a pragmatic need assisting in the development of decision making tools that better represent the drivers of placed based vulnerability in arid metropolitan regions. / Dissertation/Thesis / M.A. Geological Sciences 2011

Resumo: Nesta pesquisa foi avaliado o metabolismo de dois genótipos de milho (Zea mays L.) ao estresse hídrico e a correlação entre o teor de compostos responsáveis pela a aclimatação à limitação hídrica desses genótipos na germinação e no estádio vegetativo. Foram instalados dois experimentos. Inicialmente, um ensaio de germinação foi montado com o objetivo de verificar a tolerância de dois genótipos de milho, DKB 390 e DAS 2B710 ao déficit hídrico e de quantificar a prolina e a trealose nos tecidos endospermático e embrionário com intuito de descrever as suas funções fisiológicas na germinação. O segundo avaliou o ajustamento osmótico através das respostas bioquímicas e fisiológicas e moleculares de dois híbridos de milho sob duas disponibilidades hídricas no solo, em um latossolo vermelho. A partir desses resultados, verificou-se a tolerância destes híbridos a seca nesse estádio e o reflexo da expressão relativa de genes relacionados à síntese de solutos compatíveis em reposta à limitação hídrica no solo / Abstract: The metabolism of maize genotypes (Zea mays L.) to soil water avaibility and the correlation between the content of compounds responsible for this acclimation to water limitation of these genotypes at the germination and the silking stage. Two experiments were carried out. First, the germination test was evaluated the tolerance of two genotypes of maize, DKB 390 and DAS 2B710 to water available and also to quantify the proline and trehalose in the endosperm and embryonary axis tissues with the aim of describe their physiological functions in germination. The second assay it was examined the osmotic adjustment through biochemical and physiological responses of two hybrids growing in two soil water availability. The results of that experiment, checking the degree of tolerance of these hybrids and the reflection of the gene expression related to synthesis of these compatible solutes in response to soil water availability / Orientador: Jairo Osvaldo Cazetta / Coorientador: José Frederico Centurion / Banca: Manuel Pedro Salema Fevereiro / Banca: Carlos Alberto Martinez Y. Huaman / Banca: Janete Aparecida Desidério / Banca: David Ariovaldo Banzatto / Doutor

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