EvoluÃÃo de fatores hidrolÃgicos no reservatÃrio de Itaparica -Rio SÃo Francisco (1987, 1989 e 2002)

AUTOR(ES)

Aldemir de Castro Barros

DATA DE PUBLICAÇÃO

2004

RESUMO

The main aim of this study has been to recognize the modifications or adaptations that might have happened to the water and to the fish communities after the construction of a huge reservoir such as Itaparica (834.0km2) located in the semi arid region of the northeast of Brazil, which submerged the stunted sparse forest (caatinga). Data and information related to three periods (1987,1989 and 2002), representing respectively the lotic phase, the first year of the dam and the current situation have been used. The data has been collected in two fixed stations inside the dam. Physical-chemical parameters such as temperature, water transparency, pH, conductivity, silic, phosphorus, iron; as well as biological indicators such as DO, BDO, CDO, CO2, phytoplancton, zooplancton, ichthyofauna specific diversity and levels of chlorophyll a have been studied. Apparently, the mechanisms in the reservoir have become subject themselves to the handling of the water which resides for 2.4 months inside the dam with oscilation in its level between the 300 and 304 quotas. The multidimensional analysis of the set of data revealed the existance of two zones in the interior of the reservoir: one under the lotic influence in front of Rodelas (BA); and another with more lacustrine features towards the dam. This multidimensional analysis has also shown that in 1989 the lacustrine zone had already presented the characteristics currently (2002) observed, and that the area of Rodelas has kept the lotic characteristics. A certain capacity of self-depuration in the lake has been verified, which initially showed high levels of nutrients and chlorophyll a, followed by signs of exhaustion and later started to increase again. Phytoplancton, zooplancton, ichthyofauna have modified with frequency causing changes in the species and in the abundance of the organisms. Two exotic fish species dominate the abundance of the individuals and the species alltogether occupy niches in a balanced way. The ichthyofauna presented a dominance of iliofag fish in the lotic phase, which, along the time, gave place to predators, which currently consist of approximately 80% of the samples. Thus, some kind of support from the forage species takes place. The changes observed benefited the reservoir as far as the quality of water and its exploitable potential are concerned. The fishing species introduced in the San Francisco basin which managed to establish themselves there undergo their cycles in the interior of the reservoir facilitating the control and management of the area. The management generates the necessity to control the use of fertilizers, the implementation of a sewage system, and the deposition of the solid residue

ASSUNTO(S)

administracao publica impacto ambiental plÃncton limnologia peixes comunidades biÃticas qualidade da Ãgua

Documentos Relacionados

• Estudo da qualidade da Ãgua no reservatÃrio de Itaparica localizado na Bacia do Rio SÃo Francisco
• Use of evolutionary algorithms on hydrologic model calibration and on operation of reservoir systems
• SimulaÃÃo de reservatÃrio de petrÃleo em arquiteturas paralelas com memÃria distribuida
• Estudos sedimentolÃgicos, hidrodinÃmicos, batimÃtricos e da qualidade da Ãgua visando a evoluÃÃo e os aspectos ambientais associados do EstuÃrio do Rio Formoso - PE
• ParÃmetros hidrolÃgicos correlacionados com a biomassa e composiÃÃo fitoplanctÃnica na regiÃo costeira adjacente à desembocadura do Rio SirinhaÃm (Pernambuco-Brasil)