Estudo da bacia hidrográfica de Machico: vulnerabilidade de cheias

Esta dissertação de mestrado intitula-se “Estudo da Bacia Hidrográfica da Ribeira de Machico – Vulnerabilidade de Cheias”. Os objetivos deste estudo são: o estudo da Bacia Hidrográfica de Machico, catorze sub-bacias e secções de desembocadura destes afluentes para o curso de água principal, várias secções ao longo da linha de água principal, analisar se tais secções comportam os caudais de cálculo, elaboração de uma carta de vulnerabilidade e elaboração de uma lista de possíveis obras de intervenção e medidas a implementar. O método utilizado consistiu na identificação dos postos de monitorização de precipitação com efeito na bacia, de seguida aplicaram-se estatisticamente as amostras de precipitações máximas anuais com a duração de 1, 2, 3, 4 e 5 dias consecutivos, para que de seguida se estime a precipitação na bacia hidrográfica com o período de retorno e com a duração de 24h. Após determinação da precipitação para vários períodos de retorno, estimou-se o caudal de ponta de cheia através do método racional. Mediram-se as secções em estudo e determinou-se o caudal pela equação de Manning – Strickler nas mesmas. Após tal procedimento, verificaram-se quais as secções que não comportavam tal caudal e por fim elaboraram-se cartas de vulnerabilidade para vários períodos de retorno, quer para as secções de desembocadura de 14 sub-bacias, assim como, para as secções ao longo da ribeira de Machico. Relativamente aos resultados, foram os esperados, pois existem alguns trechos da ribeira que ainda estão por canalizar, assim como, a existência de passagens pedonais, pontes e passagens hidráulicas, onde há uma diminuição da área de vazão da ribeira de Machico. Assim sendo, tais secções apresentavam uma percentagem de preenchimento através da fórmula criada para o efeito, quociente entre o caudal pelo método racional e o caudal de Manning – Strickler, e multiplicado posteriormente por 100 %. Em termos numéricos é de constatar que para o período de retorno de 100 anos, seis das 18 secções estudadas da ribeira canalizada não comportam tal caudal líquido acabando por transbordar. Assim sendo, tem-se que 12 secções acabam por comportar tal volume de água, no entanto se juntarmos diferentes materiais tais como, solo, material rochoso e outros, essas secções não comportarão tal matéria líquida. Em suma, dever-se-á repensar e realizar obras de intervenção nos trechos onde a ribeira ainda está por canalizar como pontes e passagens pedonais. Dada a existência de um grande desnível na linha de água principal a partir do quarto quilómetro de montante para jusante, terá de haver uma série de intervenções a sul desse desnível de modo a mitigar um possível caudal que poderá advir de acordo com precipitações iguais ou superiores aos do período de retorno estudados. Por fim é importante referir que será de igual forma necessário realizar limpezas periodicamente tanto na ribeira principal como nos afluentes que nesta desaguam.

Caracterização físico-mecânica dos solos da bacia hidrográfica de Santa Luzia no âmbito do projeto "MonitorizaRibeiras" do LREC

O conteúdo da presente dissertação aborda a importância da caracterização dos solos, na medida em que estabilidade dos taludes é um fator que depende fortemente da constituição e do tipo de solo presente nos maciços. A realização deste estudo incide sobre os solos da bacia hidrográfica da ribeira de Santa Luzia. O motivo da escolha da bacia em causa prende-se com o facto de a mesma ser uma das ribeiras que, atualmente se encontra sob observação através do projeto “MonitorizaRibeiras” do LREC. Os ensaios laboratoriais de caracterização físico-mecânica dos solos constituem uma das componentes de maior relevância na engenharia geotécnica. Neste trabalho a caracterização mecânica é feita através de ensaios de corte direto (em caixa de corte), que permitem obter os parâmetros de resistência do solo (ângulo de atrito e coesão). A caraterização física foi efetuada recorrendo a ensaios simples que permitem determinar os índices físicos do solo, mais particularmente: determinação da baridade seca in situ, análises granulométricas, determinação de limites de consistência de Atterberg e do teor em água natural, densidade de partículas sólidas e determinação da quantidade de matéria orgânica. Os parâmetros obtidos permitem depois a realização de uma análise a vários taludes com diferentes inclinações, de modo a verificar que influências tais parâmetros geram na obtenção do Fator de Segurança. Verifica-se que à medida que o teor em água aumenta, essa influência traduz-se na perda de resistência de um solo. Tal análise permitiu determinar quais as zonas da bacia de Santa Luzia que com as características obtidas e nas condições estudadas se encontram em maior perigo de escorregamento. Os sensores de saturação do solo, sendo uma útil ferramenta de monitorização remota foram alvo de pesquisa nesta dissertação. Esta pesquisa foi realizada com propósito de contribuir com informação, que posteriormente auxilie, na implementação destes equipamentos no sistema do projeto “MonitorizaRibeiras”.

Eutrofização e capacidade de carga de fósforo de seis reservatórios a bacia do Rio Seridó, região semi-árida do Estado do RN

The eutrofization is a natural process of accumulation of nutrients in aquatic´s body that it has been accelerated for the human´s actives, mainly the related with the activities of camp, industrial and the inadequate disposition of the domestic sewage. The enrichment of the aquatic´s body with nutrients, mainly the nitrogen and the phosphorus, and the consequent proliferation of algae and Cyanobacteria can commit the quality of the water for the public provisioning, for the fish farming and for other ends. The problem becomes more critical when there is a shortage of water naturally as in the semi-arid area of the Brazilian northeast. Before that problem this work had as objective evaluates the trophic state of six reservoirs of the basin of River Seridó of Rio Grande of Norte and also estimate the capacity of load of match of the reservoir and risk probabilities based on the established limits by the resolution Conama 357/05. The results demonstrate that the six reservoirs are eutrofization, with concentration of total phosphorus and cloro a in the water upster to 50 e 12 μg l-1. The results show that space homogeneity exists in the state trophic of the reservoirs, but a significant variation interanual in function of the increase of the concentrations of nutrients and decrease of the transparency of the water with the reduction of the body of water accumulated in the reservoirs.The results of the simulation risk estocastic show that the reservoirs could receive annually from 72 to 216 Kg of P, assuming a risk of 10% of increasing in more than 30 μg l-1 the annual medium concentrations of total match in the water of these reservoirs. This load could be high in until 360 kg of P a year in case the managers assume a risk of 10% of increasing in more than 50 μg l-1 the annual medium concentrations of total phosphorus in the waters of these reservoirs

Diversidade Ictiofaunística e Ecologia reprodutiva de uma espécie nativa de peixe da Bacia Piranhas-Assu, RN

The Caatinga biome is rich in endemic fish species fauna. The present study the results of fish faunal surveys conducted in the hydrographic basin of Piranhas-Assu of the Brazilian Caatinga biome. The fish samples collected were distributed in four orders (Characiformes, Perciformes, Siluriformes and Synbranchiformes), 11 families (Characidae, Curimatidae, Auchenipteridae, Anostomidae, Prochilodontidae, Erythrinidae, Cichlidae, Sciaenidae, Heptapteridae, Loricariidae, Synbranchidae) and 22 species, of which 17 are endemic and five have been introduced from other basins. The order Characiformes was the most representative in number of species (46,35% ) followed by Perciformes (35,38%), Siluriformes (17,44%) and Synbranchiformes (0,5%). The Nile tilapia, Oreochomis niloticus, the only exotic species, was most expressive in number of individuals (24.92%) followed by the native species piau preto, Leporinus piau (18,77 %). Considering the relative frequency of occurrence of the 22 species, 13 were constant, five were accessory and four were occasional. This study investigated the reproductive ecology of an endemic fish black piau, Leporinus piau from the Marechal Dutra reservoir, Acari, Rio Grande do Norte. Samplings were done on a monthly basis from January to December 2009, and a total of 211 specimens were captured. The environmental parameters such as rainfall, temperature, pH, electrical conductivity and dissolved oxygen of water were recorded. The sampled population showed a slight predominance of males (55%), however females were larger and heavier. Both sexes of L. piau showed positive allometric growth, indicating a higher increase of weight than length. The first sexual maturation of males occurred at smaller size, with 16.5 cm in total length than females (20.5 cm). During the reproductive period, the condition factor and gonadosomatic index (GSI) of L. piau were negatively correlated. This species has large oocytes with a high mean fecundity of 54.966 with synchronous oocyte development and total spawning

Desenvolvimento de formulações para produção de grés porcelanato a partir de matérias-primas da região da bacia do Parnaíba

Brazil is a great ceramic raw materials productor because of the its big number of clay deposits, in various areas of the ceramic industry. Although, the majority of the natural reservations are unknown or not studied yet, so there is no scientific technical dates that can guide their usage and industrial application, as well as the racional and optimazed way of usage by the industrial sector. The state of Maranhão has a gigant mineral wealth as esmectite, bentonite, kaolin, clays, feldspates, marine salt, iron and others, but produce only products with small agregated value compared to the porcelanato, one of the most expensives ceramic cover tiles, the reason for that is the low water absorption (lower than 0,5%), beside present amazing tecnicals features, like mechanical resistence. The main objective of the work is to do the characterization of four clays, with the finallity of find an application by the results and develop formulations to produce porcelanato using these raw materials from Timon-MA. For this were made the raw materials characterization using X ray fluorecence; X ray diffraction; Differencial thermal analysis; Dilatometric analysis and Tecnological properties, planing three formulations that were sinterized at six different temperatures: 1150, 1170, 1190, 1210, 1230 and 1250ºC for 7 minutes. After the sinteratization, the samples were submitted to tension resistance analysis. Were attained two formulations with the requested properties to produce porcelanato

Adição de cascalho de perfuração da bacia potiguar em argilas para uso em materiais cerâmicos: influência da concentração e temperatura de queima.

One of waste produced on large scale during the well drilling is the gravel drilling. There are techniques for the treatment of the same, but there isn t consensus on what are the best in terms of economic and environmental. One alternative for disposal of this waste and objective of this paper is the incorporation and immobilization of gravel clay matrix to assess their technological properties. The Raw Materials used were characterized by the following techniques: Chemical Analysis by X-ray fluorescence (XRF), mineralogical analysis by X-ray Diffraction (XRD), Grain Size Analysis (FA) and Thermal Analysis by Thermogravimetry (TG) and thermodiferential (DTA). After characterizing, samples were formulated in the following percentages: 0, 5, 10, 15, 25, 50, 75, 100% (weight) of gravel drilling, then the pieces were pressed, dried (110 ° C) and sintered at temperatures of 850, 950 and 1050 ° C. After sintering, samples were tested for water absorption, linear shrinkage, flexural strength, porosity, density, XRD and test color. The results concluded that the incorporation of gravel drilling is a viable possibility for solid masonry bricks and ceramic blocks manufacture at concentrations and firing temperature described here. Residue incorporation reduces an environmental problem, the cost of raw materials for manufacture of ceramic products

Influência das tensões tectônicas na permeabilidade da formação Açu - Bacia Potiguar

The behavior of the fluid flux in oil fields is influenced by different factors and it has a big impact on the recovery of hydrocarbons. There is a need of evaluating and adapting the actual technology to the worldwide reservoirs reality, not only on the exploration (reservoir discovers) but also on the development of those that were already discovered, however not yet produced. The in situ combustion (ISC) is a suitable technique for these recovery of hydrocarbons, although it remains complex to be implemented. The main objective of this research was to study the application of the ISC as an advanced oil recovery technique through a parametric analysis of the process using vertical wells within a semi synthetic reservoir that had the characteristics from the brazilian northwest, in order to determine which of those parameters could influence the process, verifying the technical and economical viability of the method on the oil industry. For that analysis, a commercial reservoir simulation program for thermal processes was used, called steam thermal and advanced processes reservoir simulator (STARS) from the computer modeling group (CMG). This study aims, through the numerical analysis, find results that help improve mainly the interpretation and comprehension of the main problems related to the ISC method, which are not yet dominated. From the results obtained, it was proved that the mediation promoted by the thermal process ISC over the oil recovery is very important, with rates and cumulated production positively influenced by the method application. It was seen that the application of the method improves the oil mobility as a function of the heating when the combustion front forms inside the reservoir. Among all the analyzed parameters, the activation energy presented the bigger influence, it means, the lower the activation energy the bigger the fraction of recovered oil, as a function of the chemical reactions speed rise. It was also verified that the higher the enthalpy of the reaction, the bigger the fraction of recovered oil, due to a bigger amount of released energy inside the system, helping the ISC. The reservoir parameters: porosity and permeability showed to have lower influence on the ISC. Among the operational parameters that were analyzed, the injection rate was the one that showed a stronger influence on the ISC method, because, the higher the value of the injection rate, the higher was the result obtained, mainly due to maintaining the combustion front. In connection with the oxygen concentration, an increase of the percentage of this parameter translates into a higher fraction of recovered oil, because the quantity of fuel, helping the advance and the maintenance of the combustion front for a longer period of time. About the economic analysis, the ISC method showed to be economically feasible when evaluated through the net present value (NPV), considering the injection rates: the higher the injection rate, the higher the financial incomes of the final project

Diagnóstico da possível influência da atividade petrolífera em sedimentos de fundo da Bacia Piranhas-Açu, região Baixo Açu/RN

It is located in an area of increasing oil exploration, the region of the Lower Açu is at the mercy of a possible pollution generated by this economic activity, which includes various chemical substances harmful to health, such as metals. This thesis aims to, diagnose the areas of River Piranhas-Açu, a region of the Lower Açu, which are polluted by traces factors and more. In this study, it was determined the concentration of the chemica elements Al, CD, Cr, Cu, Fe, Mn, Ni, P, Pb, V and Zn, through the technique of ICP-OES analysis and the size of sediments and their contents organic matter. Were mapped by GPS, 12 points from collections. The interpretations of the results, together associating that allowed pollution to a possible contamination by oil activity. The results showed tha some regions have low concentrations of cadmium, lead, copper, manganese and zinc unable to promote damage to human health. However, there are places where the concentrations of certain metals chromium, iron and zinc are moderately polluted compared to the results with the reference values of literature and others that are highly polluted by iron. However, due to a greater number of wells in production in those locations, those higher concentrations, it can be suggested a possible influence of oi production in some areas with concentrations of chromium and lead are higher than the rest of the points of monitoring. Moreover, it is observed that the highest levels of metals found in sediment of finer texture and more organic matter content