Prospecção da crise hídrica por meio da modelagem hidrológica no rio São Francisco

Abstract

The São Francisco river basin is threatened by a situation of increasing scarcity and poor use of water resources, which put at risk the sustainable development and protection of the environment in the region. Problems related to poor water management have been spreading throughout the planet, not being an exclusive problem in Brazil, since the establishment of the National Water Resources Policy (Law n. 9.433, January 8, 1997), the theme is approached from foundations such as the search for multiple uses guarantee; the river basin as a territorial unit for planning and action; the recognition that water is a public domain asset (endowed with economic value); being a natural resource limited and therefore should have its management decentralized and counting with the support of the Public Power, users and communities. For good planning, management and use of water resources, a rapid understanding and decision-making is necessary, especially due to the scarcity and poor distribution of the monitoring system in the country. The water catchment area of the São Francisco river, which has national importance, has presented a worrying picture of the water crisis, which officially began in 2013, when the historic reduction of the minimum deflection of 1,300 m³.s- 1 to 1,100 m³.s-1 that has been aggravated. Its flows have been maintained in the order of 550-523 m³.s-1, without significant variations. Thus, it is proposed the use of hydrological modeling, with emphasis on the clarification of the phenomenon of the water crisis, where water production of the São Francisco river basin is studied from two models, TANK MODEL and SWAT (Soil and Water Assessment Tools). It concluded that the river flows have a strong negative trend, with 1st order coefficients for the period between 2004 and 2016 ranging from (-104.01) to (-146.32). The TANK MODEL model was calibrated (NSE 0.72) and validated (NSE 0.68), generating stationary long-term flows, which served as a support for the clarification that: although real, precipitation reductions are not sufficient justification to explain the severity of the decline in water production. In this sense, it is necessary to expand the discussions about the environmental variables, their interactions and a new orientation regarding the Planning and Management of the water resources in the basin.