Modelo físico-matemático para alocação de água de pequenos reservatórios na agricultura irrigada em regiões secas (NeStRes)

• Ano de defesa: 2021
• Autor(a) principal: Brasil, Paulilo Palácio
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Agricultura de pequena escala; Operação de reservatório; Maximização da renda; Escassez hídrica; Irrigação; Mudança de paradigma; Small scale agriculture; Reservoir operation; Income maximization; Water scarcity; Irrigation; Paradigm change; Drylands
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/62444

The availability of water in dry inhabited environments has generally been promoted by large strategic reservoirs, but small non strategic ones, built by farmers and communities, are unable to cope with long term droughts and are inadequate for human supply. However, small reservoirs promote the spatial distribution of water and play an important role for livelihoods in rural areas. To fill the gap in operating methods for non strategic reservoirs used for irrigation, where water is a limiting factor, the NeStRes model was developed. The model is composed of three operating modules: i) hydrological: to define the guarantee of water withdrawals from the reservoir; ii) agricultural: to simulate agricultural production based on water availability; iii) economic: to calculate the possible income from irrigated crops. Initially, NeStRes was applied in 91 reservoirs located in the semiarid region of the Banabuiú River Basin BRB, Brazil as a case study. The simulations indicated that the maximum yield with maize cultivation is obtained when the reservoirs are intensively used, completely drying out in one to two thirds of the time. The adoption of a fixed level of reliability in the daily water supply is capable of returning good revenue results in the simulated reservoirs. Subsequently, the model was applied in 412 reservoirs located in the state of Ceará, which has 93% of the territory inserted in the semiarid region of Brazil. Thus, the simulations allowed to propose regional water use patterns governed by the hydrological regime: the maximum income from corn irrigation is obtained when the specific consumption of water (ie, the proportion of daily water withdrawal by the storage capacity of the reservoir ) is in the range of 4 L.day ¹ per m³ of reservoir storage capacity (in drier regions) to 6 L.day ¹ per m³ of reservoir capacity (in wetter areas of the coast and at high altitudes) . The methodological procedure presented in this study supports farmers' decisions and can be useful to define criteria for the operation of reservoirs in other dry regions, allowing the maximization of income and avoiding the adoption of fixed rates of water consumption for irrigation