Otimização do aproveitamento da disponibilidade de águas superficiais na bacia do ribeirão Entre Ribeiros

• Autor(a) principal: Oliveira, Josiane Rosa Silva de
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3581
• topic: Água; Recursos hídricos; Bacias hidrográficas; Water; Water resources; Basin hidrografic; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

For planning and management of water resources it is of fundamental importance to have a proper knowledge of both water availability and demands of a basin. When there is an imbalance among these factors situations of water scarcity and conflicts between users are evident. Granting of the right to use water, an instrument of the National Policy of Water Resources, aims to adjust demands and availability to ensure compliance with current and future water uses, in terms of adequate quantity and quality. Granting of water use is dependent on availability of water in the basin. The criteria for conceding water use grants are based on percentage of use of minimum flows observed during periods of drought (reference flows). However, especially in areas with high seasonal variation, the use of small percentages of the calculated flows for critical periods of the year restricts the greater use of water in months outside of the drought period. Considering that seasonal availability and use of less stringent criteria are alternatives that may provide better water use, and consequent reduction of current and potential conflicts, the objective of the present study is to characterize the demands of water use; quantify reference flow, annual and monthly bases, and address water availability; assess the impact of using different licensing criteria for water availability; and identify regions in the hydrography where implementation of regularization is necessary, performing a case study for the Entre Ribeiros river basin. To quantify the removal of water from the basin, archives of the Minas Gerais Institute of Water Management (IGAM) were consulted and to quantify availability, the regionalization of the reference flow was performed, obtained in annual and monthly bases. From the demand and availability data of the basin, evaluation of substituting annual flows by monthly flows was performed, as well as the use of different granting criteria on water availability of the basin. Evaluated were the: current criteria, based on using 30% of the annual Q7,10 and the proposed criteria, based on the use of 30% of monthly Q7,10 and 50% of the annual and monthly Q7,10. Even after using the criterion of 50% of the annual Q7,10 the natural availability was not sufficient to meet the demands, and an analysis was conducted to identify the regions where flow regulating reservoirs are needed as long as there is no absence of demands in relation to availability in the basin. Based on the results obtained, it can be concluded that: a) the demands are more concentrated in the southern and eastern regions of the basin and the associated values present significant variation over the year; b) substitution of annual Q7,10 for monthly Q7,10 generally results in an increase in water availability along the year; c) most of the hydrography regions with licensing of water use presented a sum of flow demands greater than 30% of the annual Q7,10 in all months, with greatest values in February and lowest in October; d) changing the criteria of 30% to 50% of the annual Q7,10 promoted increases ranging from 5% (in August) to 170% (in February), e) using the criterion of 30% of the monthly Q7,10 resulted in increases up to 209% along the year in the regions in which the sum of licenses did not surpass the maximum flow allowed, with exception of the months of October and November; f) the increase in regions with total demands less than availability obtained with use of 50% of the monthly Q7,10 was lower in the months of September, October and November, representing an average of 17% and higher in other months, ranging from 33% in August to 265% in February, and g) even when adopting 50% of the monthly Q7,10, there were still regions where the sum of demands surpasses availability, however the implementation of nine regulation reservoirs resulted in meeting all the demands without exceeding the maximum flow granted for the basin.