Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The study area, the reservoir GaviÃo, is positioned in the northeastern state of Ceara, is inserted in the municipality of Pacatuba and located upstream of the Water Treatment Plant - ETA, responsible for supplying drinking water in the Metropolitan Region Fortaleza.Os reservoirs in the state of CearÃ, specifically those located in metropolitan areas of the basins, such as dam Hawk, are targets of impacts resulting from various human activities developed along its watershed. Water eutrofizadasproporcionam greater difficulty and high treatment costs, mainly due to the presence of excessive algae. This increasing growth of algae in the waters are the result of continuous delanÃamentos nutrients, especially nitrogen and phosphorus, which modify the characteristics of water bodies as well as its quality. An important tool for the definition of strategies recovery, storage and management of a watershed is to determine the nutrient load, which has the purpose of evaluating the eutrophication process over a system as well as determining the mass balance through estimates of inputs, outputs and retention of nutrients in the water body. To this end, samples were collected monthly from December 2010 to May 2011, at five different points of the dam, in order to study the mass balance of macronutrients, check the quality of stored water, draw vertical profiles of physical and chemical parameters and determining the limiting nutrient in the system. During the study period, the dam has accumulated over 28.06 tons of 121.42 tons of phosphorus and nitrogen. The concentrations of the investigated parameters estÃocada higher and higher and the limitation has always been of the nitrogen fraction (N / P <10), the reservoir GaviÃo may be classified as eutrophic

A eutrofizaÃÃo à um problema que vem trazendo cada vez maiores preocupaÃÃes à comunidade cientÃfica que se dedica ao estudo dos ecossistemas aquÃticos. Hà mais de 30 anos que sÃo buscados mÃtodos para melhor entender o desenvolvimento do fenÃmeno, principalmente por meio da modelagem matemÃtica. Capaz de inviabilizar o uso humano e industrial de um reservatÃrio, a eutrofizaÃÃo deve ser motivo de constante preocupaÃÃo dos gestores dos recursos hÃdricos, pois uma vez instalada, o tempo necessÃrio para recuperaÃÃo de um reservatÃrio à da ordem das dezenas de anos. Na RegiÃo Metropolitana de Fortaleza, o aÃude Acarape do Meio à um dos mais importantes reservatÃrios para uso industrial e humano, e seu processo de eutrofizaÃÃo vem se intensificando nos Ãltimos anos. A Companhia de GestÃo dos Recursos HÃdricos â COGERH tem buscado maneiras de entender o funcionamento do reservatÃrio, atravÃs de constante monitoramento. Neste trabalho busca-se fazer um relato da situaÃÃo atual do Acarape do Meio, juntamente com prognÃsticos, obtidos por meio do modelo matemÃtico do software PAMOLARE, elaborado pelas NaÃÃes Unidas. Com isso foi possÃvel o estabelecimento de limites de poluiÃÃo que o referido reservatÃrio deve receber para que seu processo de eutrofizaÃÃo seja revertido. / Eutrophication is a problem that is becoming more important within the scientific community that studies the aquatic ecosystems. Methods for a better understanding of the phenomenon are object of research since the 70Âs, mostly through mathematical modeling. Being able to avoid the human and industrial use of a reservoir, eutrophication must be a reason for a everyday concern of water resources managers, as once it is set up, the time needed for recovery of a reservoir is usually no less than 10 years. At Fortaleza Metropolitan Region, the Acarape do Meio reservoir is one of the most important ones for industrial and human use, and its eutrophication process is intensifying during the last years. The local water resources management company (COGERH) is looking for ways to better understand the reservoir behavior through a constant monitoring campaign. Within this work it is made a report of the recent situation of Acarape do Meio, together with prognoses, obtained with the mathematical model of the PAMOLARE software, developed by the United Nations. Pollution limits were defined as an objective to revert the eutrophication process.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O processo de armazenamento de Ãgua em regiÃes semi-Ãridas tem se tornado um considerÃvel meio de reduzir a escassez deste recurso natural. Assim, à comum em regiÃes, com caracterÃsticas do Nordeste Brasileiro, a construÃÃo de grandes reservatÃrios, que tem servido para atender, com certa regularidade, demandas para os mais diversos usos. Por outro lado, o armazenamento de Ãgua em reservatÃrios acaba tornando essas massas lÃquidas vulnerÃveis a um maior risco de degradaÃÃo. Como se sabe, a Ãgua armazenada fica sujeito a longo tempo de residÃncia, permitindo assim com que algumas importantes reaÃÃes, tanto do ponto de vista quÃmico, como biolÃgico, possam ocorrer. Estas reaÃÃes, associadas com alguns lanÃamentos de efluentes, provenientes de zonas urbanas, Ãreas industriais e zonas rurais, acabam por acelerar o processo de envelhecimento dos reservatÃrios, conhecido como âprocesso de EutrofizaÃÃoâ, que depende, fundamentalmente, da disponibilidade de nutrientes no interior dos reservatÃrios. Este trabalho estudou, atravÃs de pesquisa de campo, associada com uma metodologia de cÃlculo de Ãndices de Estado TrÃfico Modificado e Ãndice de Qualidade de Ãgua, as condiÃÃes ambientais do ReservatÃrio Acarape do Meio, no Estado do CearÃ, na busca de uma identificaÃÃo das principais transformaÃÃes nos seus nÃveis trÃficos, bem como, na identificaÃÃo das principais causas de um possÃvel processo de eutrofizaÃÃo do mesmo. Para isso foram utilizados dados de campo em um perÃodo de 2001 a 2006, o que permitiu conhecer as caracterÃsticas pertinentes à estratificaÃÃo deste corpo hÃdrico, no que diz respeito à temperatura e a estratificaÃÃo quÃmica de suas Ãguas. TambÃm, tendo em vista os vÃrios pontos de coletas de dados, foi possÃvel apresentar resultados relativos ao Ãndice de Estado TrÃfico e ao Ãndice de Qualidade de Ãgua, em uma distribuiÃÃo espacial do reservatÃrio, mostrando, assim, os vÃrios pontos crÃticos do mesmo. Nas questÃes pertinentes ao Ãndice de Estado TrÃfico foram usados dois cÃlculos, sendo para o primeiro usado, apenas, a clorofila-a e o fÃsforo, enquanto que no segundo cÃlculo foram utilizados, alÃm dessas duas substÃncias, o ortofosfato solÃvel presente naquelas Ãguas. Os resultados mostram que hà uma forte variabilidade da qualidade das Ãguas deste reservatÃrio, mas que, nos anos de 2004 e 2005, suas Ãguas atingiram um nÃvel hipereutrÃfico, o que representa a presenÃa de um forte aporte de nutrientes provenientes das entradas do reservatÃrio e, provavelmente, das zonas rurais que existem em torno do mesmo. Os resultados mostraram ainda que, mesmo que a variaÃÃo vertical de temperatura nÃo seja tÃo significativa no interior do reservatÃrio, hà uma forte presenÃa de estratificaÃÃo quÃmica nas camadas mais profundas deste corpo hÃdrico. / The process of storage of water in semi-arid regions has become a considerable way of reducing the shortage of this natural resource. Like this, it is common in areas with characteristics of the Brazilian Northeast, the construction of great reservoirs that has been being to assist, with certain regularity, demands for the most several uses. On the other hand, the storage of water in reservoirs bring some vulnerabilities to the water, concerning with the degradation risk. As it is known, the stored water is subject to long residence times, allowing the appearance of some important chemical and biological reactions. These reactions, associated with some sewage releases, that come from urban, industrial, and rural areas, promote the accelerating the process of aging of the reservoirs, known as Eutrophication Process, that depends, fundamentally, of the presence of nutrients inside the reservoirs. This work studied, through field data, associated with a methodology of calculation of Modified Trophic State Index and the Water Quality Index, the environmental conditions of the Acarape do Meio Reservoir, in the State of CearÃ, trying to identificaty the main transformations in their trophic levels, as well as, the identification of the main causes of a possible process of eutrophization of it. The data cover the years 2001 through 2006. With that, it was possible to know the characteristics concerning with the stratification this body of water, with respect to temperature and the chemical process. Also, considering the several points of collections of data, it was possible to present results concerning with the Trophic State Index and the Water Quality Index, a long of the all surface of the reservoir, showing, like this, the several critical points of it. With respect to the Trophic Level Index, two calculations were used, being for the first used, just, the chlorophyll a and the phosphors, while in the second calculation they were used, besides those two substances, the present soluble orthophosphate in those waters. The results show that there is a strong variability of the quality of the waters of this reservoir, but that, in the years of 2004 and 2005, their waters reached a hipereutrophic level, that represents the presence of a fort presence of nutrients coming of the entrances of the reservoir and, probably, of the rural areas that exist around the it. The results showed yet, even if the vertical variation of temperature is not so significant inside the reservoir, there is a strong presence of chemical stratification in the deepest layers of this body of water.