Methodology for Optimizing Water Use in Shared Management Schemes Under Conflict Conditions

摘要

The granting of permits for the use of water resources has been legislated to ensure adequate access to water for all user sectors. However, this management instrument may not effectively perform quantitative control over the granting process, and permits for flows greater than the water availability may be granted and thus are not always representative of the actual abstractions. Therefore, the present study aimed to develop a methodology to optimize the use of water in shared management schemes under conflict conditions. The proposal is based on the initial evaluation of water availability conditions within a legal plan, in which the flows that consider all uses are associated with the annual run-of-river water availability, and, subsequently, for the segments where the demands are higher than the availability, on the analysis of water availability condition in an operational plan. At the operational level, the demands are characterized by the permitted flows that consider all uses except those corresponding to irrigation activities, which are estimated based on the flows required by the equivalent hectares. In this plan, the availability is considered on a monthly run-of-river basis and with the presence of flow-regulation reservoirs. For the application of the proposed methodology, the Rio Branco basin in western Bahia State is considered. The results indicated that management bodies require extensive knowledge of the actual abstractions corresponding to the permits granted, the potentialities of considering the minimum monthly run-of-river water availability and potential water availability of the basin under regulated-flow conditions, changes in cropping calendars and the use of deficit irrigation under conditions with conflicts over water use.