Modelagem hidro-econômica aplicada à cobrança pelo uso da água bruta.

Abstract

Economic instruments have been used to promote water conservation and raise funds to finance water resources. The study proposes changes in the current model of State of Ceará’s raw water collection incorporating climate variability and the costs of the Transposition of the São Francisco River. To do so, we verified the impact of droughts on water costs and collection during the period 2011-2019 to answer the following questions: Does collection fulfill its function of financing the water resources system? Is the pricing model flexible to absorb the effects of climate variability? In this chapter we divided the methodology into two parts: content analysis and analysis of the system's operationalization costs. In the next step, we proposed a hydro-economic model using the floating tariff according to the levels of the reservoirs. It was developed according to the unit payment capacity (CPU) and the State Indices of the hydrographic regions. Finally, we built a cost allocation proposal considering the transposition waters and applying Game Theory. The model was applied to the Jaguaribe-Metropolitano-São Francisco System in which there are conflicts in periods of water scarcity regarding water use. The cost allocation methodology considered the floating tariff and the Shapley value to obtain an apportionment parameter between water uses. We found that the State Index is negatively correlated with the AO&M costs, and that the revenue generated is directed almost entirely to these costs, being insufficient to finance the measures, programs, and projects to improve the respective basins. The hydro-economic model allowed average revenues to exceed AO&M costs by allowing the financing of the actions of the State Water Resources Plan. Finally, the floating tariff was applied in the model of allocation of costs of the transposition waters, and it was found that the largest portion of payment and, consequently, of benefits is the human supply of the Metropolitan Region of Fortaleza. In addition, there were benefits in all coalitions, highlighting that cooperation between players is essential. Thus, we analyzed the economic efficiency of the collection of raw water, in which the proposed model intends to assist in decision making, planning and management of water resources.