Banca de DEFESA: Eduardo Paulino da Silva

EVALUATION OF COLLECTIVE GRANTING SCENARIOS IN CONFLICT REGIONS OVER THE USE OF WATER THROUGH WEAP.  CASE STUDY: FORMOSO-TO RIVER BASIN

WEAP, Collective Grant, High Level Management.

The Formoso River Hydrographic Basin (BHRF), located in the Tocantins, has faced a severe shortage of water resources during the dry period, resulting from reduced rainfall and intense irrigated agriculture, triggering conflicts between farmers and other sectors. In 2016, several sections of the main rivers of the basin, the Formoso and Urubu, completely dried, leading to the suspension of the withdrawal of water resources and the ban of any undertaking subject to environmental impacts. Faced with this scenario, the Federal University of Tocanitns (UFT) developed the water resources management system called High Level Management (GAN). However, the phase of this project related to the revision of the bombs' orders and operating rules has not been completed. After some public hearings, a Working Group developed the 2018-2019 Biennial Plan with the operational organization of the proceeds, specifically for the critical period. However, like the final phase of the GAN, this organization has not been implemented. In this sense, the present study carried out the hydrological modeling of the BHRF through the WEAP and simulated the scenarios A and B of the Biennium Plan, which refer to different rules of operation of water pumping in conflict regions. The remaining flows obtained in each of these regions were assessed considering that users are subject to a collective grant, in which an environmental flow must be preserved down from the absorption pumps. Two environmental flow values were considered, one more restrictive, obtained from the monthly Q95 reference flow, and another more flexible, calculated through the seasonal Q90. The modeling was carried out for the period from July 2018 to June 2021, considering a daily time step. The calibration of the model obtained satisfactory adjustment statistics for the three considered river stations: Foz Rio Formoso (NSE = 0.89), Project Río Formoso (NSE= 0.89) and Foz Río Urubu (NSA= 0.79). The results of the remaining flow for the PB-A and B-B scenarios in July are similar. In critical elevation sections, the remaining flow exceeds the most flexible limit of environmental flow on most days, however, the same is not the case when comparing these values with the most restrictive limit. On the other hand, the remaining flow results in critical downstream sections generally exceed the restrictive environmental flow limit, largely due to the upstream rotation rules.