Determinação e análise de indicadores de desempenho e de sustentabilidade de seis açudes na bacia do rio Piancó-PB e de suas potenciais demandas.

Abstract

The consequences of economic development, especially the increase in the intensity and variety of water resources uses promote the disequilibrium between demand and supply, causing constant conflicts among users, mainly in regions with scarcity of resources. Such conflicts, together with the necessity for integrated planning and operation as well as the restrictions imposed to the systems make it difficult to establish efficient operational policies. This work has investigated the planning and operation a six-reservoir system, located within the Pianco River basin in the semiarid region of the State of Paraiba. The objective has been to verify the potential use of their water resources for irrigation and evaluate their sustainability criteria. Performance estimates for the areas potentially irrigated by such reservoirs as well as sustainability and vulnerability measures for their contribution basins have also been calculated. In this study, hydrological and agricultural scenarios have been taken into account. Under such scenarios, the water use of each reservoir for irrigation purposes has been optimized. For each scenario, a nonlinear optimization model has been applied in order to define the optimal cropping areas and the amount of water to be allocated at each month by each reservoir. Later, a simulation model to study the system's behavior in order to meet the optimal demands found by the optimization model has been applied. With the outcomes from the simulation process, sustainability criteria for the reservoirs, namely, reliability, resiliency and vulnerability have been estimated. The results showed that three of the six reservoirs properly met the demands proposed by the optimization model and obtained reliability levels higher than 76%. However, the other three have achieved levels varying only between 36.2% and 45.4%, demonstrating a high failure percentage. Five of the six reservoirs provided low resiliency, i.e., low recovery capacity from failures. As for vulnerability, the obtained values reflected the climate characteristics of semiarid regions, in which the water deficit is high when failures occur, and varied in average from 75.3% to 94.6% of the demands. Concerning the sustainability of the reservoir contribution basins, the data of water availability for the calculation of the criteria require more, inspections given the fact that some incoherent values were obtained. The performance indicators for the potentially irrigated areas were satisfactory as compared to the ideal ones.